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PALEOBIOLOGY OF GIGANTOPTERIDS

FROM THE UPPER PERMIAN OF GUIZHOU PROVINCE, CHINA

DISSERTATION

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of the Ohio State University

by

Hongqi Li, B.S., M.S.

*****

The Ohio State University 1996

The Dissertation Committee: Approved by

William A. Jensen, Advisor

David W. Taylor

Fred D. Sack Advisor

Morris G. Cline Department of Plant Biology UMI Number: 9639283

UMI Microform 9639283 Copyright 1996, by UMI Company. AH rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code.

UMI 300 North Zeeb Road Ann Arbor, MI 48103 To My Dear Wife, Yanling Fan

11 ACKNOWLEDGMENTS

This research was financially supported by several institutions and organizations. These include: Geological Society of America (Research Grant, 5195- 93), the Botanical Institute, Academy of China (Research Aid to Visiting Scholar), the Graduate School, The Ohio State University (Graduate Student Alumni Research Award), and the Department of Plant Biology, The Ohio State University (Graduate Teaching and Research Associateships). Their assistance is hereby gratefully acknowledged.

Thanks go to numerous individuals for their various contributions to this investigation. Professor Baolin Tian, at the Beijing Graduate School, China University of Mining and Technology, has provided his advice, encouragement, and personal help. Professor Meitang Mei, Drs. Yingting Guo and Sherong Hu, as well as other colleagues of this university helped me a lot in collecting materials. Dr. Chengsen Li and the paleobotany group at the Beijing Botanical Institute, Academy of China financially supported my visit and field work. Mr. Lianwu Zhang, Mr. Jingren Ma, and other geology engineers at the coal mines of Shuicheng and Panxian, Guizhou, China were very helpful in my fossil-collecting.

I am grateful to Dr. Paul Kenrick and the staff of the Swedish Museum of Natural History for loaning the specimens of Gigantopteris nicotianaefolia. I would like to thank Drs. Sergius H. Mamay and William A. DiMichele at the National Museum of Natural History, Smithsonian Institution for providing much assistance during my visit at the museum. I am appreciative of the following individuals for reading my papers: Drs. Benton M. Stidd, Tom L. Phillips, David L. Dilcher, and Sergius H. Mamay.

iii I am deeply grateful to Dr. David Winship Taylor of the Indiana University Southeast. As an invited member of my Dissertation Committee, he spent tremendous time reading my manuscript, and provided a lot of help in both professional and personal aspects.

I express sincere appreciation to Drs. Thomas N. Taylor, Edith L. Taylor, Morris G. Cline, Tod F. Stuessy, Fred D. Sack, and William A. Jensen, for their tremendous time serving on my Advisory, General Examination, and Dissertation Committees. Gratitude is expressed to Drs. Thomas N. Taylor and Edith L. Taylor, my previous advisors, for their guidance and insight before they moved to The University of Kansas. I am deeply grateful to Dr. William A. Jensen for his willingness to be the succeeding advisor. Dr. Ralph E. J. Boerner, the Chairman of the Department of Plant Biology, and Dr. Fred D. Sack, the Chairman of Committee of the Graduate Studies, should also be acknowledged for their support and encouragement.

To my parents, Zhaocong Li and Xiuqing Liu, in the remote China, I express my sincere thanks for forgiving my absent obligation. For my daughter, Dianna Li, I thank you for understanding my frequent absences. To my wife, Yanling Fan, I offer you my special thanks for your unshakable faith in me and your support to my endeavors, without which this dissertation would not have been possible. For this reason, this dissertation is dedicated to you.

IV VITA

April 17, 1955 ...... Born - Weifang, Shangdong, P. R. China

10, 1978 - 7, 1982 ...... B.S. in Geology (Paleontology), Nanjing University, Nanjing, P. R. China

8, 1982 - 7, 1985 ...... M.S. in Coal Geology (Paleobotany), Beijing Graduate School, China University of Mining and Technology, Beijing, P. R. China

8, 1985 - 8, 1987 ...... Instructor, Beijing Graduate School, China University of Mining and Technology, Beijing, P. R. China

1986 - 1990 ...... Secretary, Coal Geology Department, Beijing Graduate School, China University of Mining and Technology, Beijing, P. R. China

9, 1987 - 9, 1990 ...... Assistant Professor, Beijing Graduate School, China University of Mining and Technology, Beijing, P. R. China

10, 1990 - 8, 1996 ...... Graduate Teaching/Research Associate, the Department of Plant biology. The Ohio State University, Columbus, Ohio

8, 1996 - ...... Postdoctoral Researcher, Biology Instructor, Department of Biology, Division of Natural Sciences, Indiana University Southeast, New Albany, Indiana PUBLICATIONS

1996, Li, Hongqi, Edith L. Taylor, and Thomas N. Taylor: Permian Vessel Elements. Science, 271: 188-189.

1994, Li, Hongqi, Baolin Tian, Edith L. Taylor, and Thomas N. Taylor: Foliar Anatomy of Gigantonoclea guizhouensis (Gigantopteridales) from the Upper Permian of Guizhou Province, China. Amer. Jour. Bat., 81(6): 678-689.

1994, Li, Hongqi, Edith L. Taylor, and Thomas N. Taylor: Disjunct distribution of gigantopterids between Cathaysia and western North America. Amer. Jour. Bot. 81:6 (Supplement-Abstract): 95-96.

1994, Li, Hongqi, Edith L. Taylor, and Thomas N. Taylor: The paleophytogeographic classification of Cathaysia and Gigantopteris Kingdoms. Amer. Jour. Bot. 81:6 (Supplement-Abstract): 96.

1993, Li, Hongqi, Edith L. Taylor, and Thomas N. Taylor: The Axial Anatomy of Gigantopterids from the Upper Permian of Guizhou Province, China. Amer. Jour. Bot. 80:6 (Supplement-Abstract): 90-91.

1992, Tian, Baolin and Hongqi Li: A New special Petrified Stem, Guizhouoxylon dahebianense gen. et sp. nov., from Upper Permian in Shuicheng District, Guizhou, China. Acta Palaeontologica Sinica, 31(3): 336-345 (in Chinese and English).

1992, Li, Hongqi, Edith L. Taylor, and Thomas N. Taylor: The Anatomy of Gigantopterid Stems from the Upper Permian of China. Abstracts of the IVth lOP, p. 99 (Paris, French).

1990, Li, Hongqi and Baolin Tian: Anatomic Study of the Foliage leaf of Gigantonoclea gidzhouensis Gu et Zhi. Acta Palaeontologica Sinica. 29(2): 216- 227, Pis., I-III. (in Chinese with English summary).

1988, Tian, Baolin, Yingting Guo, Shijun Wang, Hongqi Li, and Shimin Ma: Systematic and Taxonomic Study on some Groups in Cathaysia Flora. In Collections of Teaching and Researching Papers. Beijing Graduate School, China University of Mining and Technology (I): 212-220; Pis., I-Ill, CUMT Press (in Chinese).

1988, Li, Hongqi: The First Anatomy Study on Fossil Gigantopterids. In Collections of Teaching and Research Papers. Beijing Graduate School, China University of Mining and Technology (I), p. 344, CUMT Press (in Chinese)

VI 1988, Tian, Baolin, Hongqi Li, and Yingting Guo: Discussion on the systematic position of Gigantopterids. Publication No. 1 o f the 3rd lOP (Melbourne, Australia).

1987, Tian, Baolin, Yingting Guo, Shijun Wang, and Hongqi Li: Study on the Paleozoic Coal Balls and Floras in China. The Abstracts o f Papers o f the 11th International Carboniferous Conference (I): 126. (Beijing, China)

1987, Tian, Baolin, Yingting Guo, Shijun Wang, and Hongqi Li: A Preliminary Study on the Taxonomy of Cathaysia Flora. The Abstracts o f Papers of the 11th International Carboniferous Conference (I): 127.

1986, Baolin Tian, Yingting Guo, Shijun Wang, and Hongqi Li: Study on some Systematic and Taxonomic Problems of Cathaysia Flora. Paper Collections of the National Conference of Carboniferous Coal-Beating Strata and GeoloQ/. p. 84-85 (in Chinese. Changsha, China).

1986, Tian, Baolin, Yingting Guo, Shijun Wang, and Hongqi Li: The Paleozoic Coal-Balls and Floras of China. Paper Collections of the National Conference o f Carboniferous Coal-Beating Strata and Geology, p. 88-89.

1984, Tian, Baolin, Yingting Guo, and Hongqi Li: The Late Upper Permian Flora of China. Abstracts o f Contributed Papers and Poster Session, The 2nd lOP, p. 4, (Edmonton, Canada).

1984, Tian, Baolin, Yingting Guo, and Hongqi Li: The Late Upper Permian Flora. Symposium on Carboniferous-Permian Coal-Beating Strata o f North China, p. 23-24 (in Chinese. Taiyuan, Shanxi, China).

1984, Guo, Yingting and Hongqi Li: A Special Fossil of Petrified Plant - Carbonaceous Concretion. Coal Geology and Exploration, 1984 (5): 14, PI. I (in Chinese).

FIELDS OF STUDY

Major Field: Plant Biology Paleobotany

Vll TABLE OF CONTENTS

DEDICATION ...... ii ACKNOWLEDGMENTS...... iii VITA ...... V TABLE OF CONTENT...... viii ABSTRACT...... xi

CHAPTER Page

I. IN TRO D U CTIO N ...... 1

II. MATERIALS AND METHODS...... 8 Research History of the Region ...... 8 Geographic Occurrence ...... 9 Geological Setting and Depositional Environment ...... 9 Components of the Flora ...... 11 Preservation and Preparation Methods ...... 12 Specimens ...... 13

III. GIGANTOPTERID LEAF ARCHITECTURE...... 14 A bstract...... 14 Introduction ...... 15 Leaf Outline ...... 16 Leaf Types and their Application to Classification ...... 26 Evolutionary Significance ...... 28

rv. FOLIAR ANATOMY OF GIGANTOPTERIDS ...... 35 A bstract...... 35 Introduction ...... 36 Description of Gigantonoclea guizhouensis ...... 37 Description of Gigantopteris dictyophylloides ...... 45 Systematics...... 50 Discussion ...... 55

viii V. MORPHOLOGY AND ANATOMY OF GIGANTOPTERID AXES 62 A bstract...... 62 Introduction ...... 63 Systematics and Description ...... 64 Spinivinea gen. nov ...... 64 Vasovinea gen. nov ...... 68 Reconstruction ...... 74 Ecology ...... 76 Phylogeny ...... 81 VI. THE ASSOCIATED SEED S...... 88 A bstract...... 88 Introduction ...... 89 Description ...... 90 Discussion ...... 90

VII. THE ASSOCIATED SYNANGIA...... 104 A bstract...... 104 Introduction ...... 105 Systematics and Description ...... 106 Guizhoutheca inanibasis gen. et sp. nov ...... 106 Guizhoutheca? sp...... 110 Discussion ...... I l l

VIII. PALEOPHYTOGEOGRAPHY OF GIGANTOPTERIDS...... 120 A bstract...... 120 Introduction ...... 121 The Gigantopteris B iom e ...... 125 Classification of the Cathaysian Region ...... 131 Some Mixed Floras in the South Paleo-Tethys ...... 144 Some Mixed Floras in the West Paleo-Tethys ...... 147 Reconstruction of the Paleo-Tethys ...... 148 Conclusion ...... 155

IX. GENERAL DISCUSSION...... 158 Reconstruction of Gigantopterid Plants ...... 158 Ecology of Gigantopterids ...... 160 Systematic Affinities ...... 162 Geography of Gigantopterids ...... 165

IX APPENDICES

A: T ables...... 167 1. Koidzumi’s (1936) Classification of Gigantopteridaceae ...... 167 2. Asama’s Gigantopteridaceae and the three Evolutionary Series .... 168 3. A Partial List of Gigantopterids ...... 169 4. Correlation of the Upper Permian Formations of Shuicheng and Panxian, Guizhou ...... 170 5. Plant Assemblage Zones in the Upper Permian of Panxian 170 6. Directory of Compression and Impression Specimens used in the Dissertation ...... 171 7. Directory of Dissected Permineralized Specimens ...... 172 8. Classification of Gigantopterid Venation...... 174 9. Seed-bearing Pteridosperms from China ...... 175 10. Plant Assemblages of North and South China ...... 176 11. The Distribution of some Key Gigantopterid Genera in China .... 176 12. Correlation of Lower Permian Gigantopterids between North American and China ...... 177 13. Stratigraphie Classification of the Upper Paleozoic in North China Province ...... 178 14. The Nanshan Flora in Tarim-Qilianshan Province ...... 178 15. Qiibu Flora in South Tibet ...... 179 16. Phytogeographic Classification of Late Paleozoic ...... 179 B: Figures ...... 180

REFERENCES...... 250 ABSTRACT

Gigantopterids are a group of Permian (about 280 million years ago) plants that existed in the Cathaysian flora plus a few taxa reported from southwestern

North America. Cathaysia flora occupied China, Japan, Korea, and other

Southeastern Asian countries, and has been commonly referred as the Gigantopteris flora for the dominated gigantopterids. Many gigantopterids have large broad leaves with reticulate venation so that they are similar to those of extant Gnetum and certain angiosperm plants. However, their systematic affinities remain enigmatic since this group have been known limited to their leaf morphology mainly, except some recently reported foliage anatomy.

Many compressed, impressed, and permineralized gigantopterid organs have been collected from the Upper Permian strata of western Guizhou Province, China and used in this research. For the first time, the leaf architectures of gigantopterids have been summarized, and an actinodromous type has been recognized, based on the present material and previous studies. With the permineralized material, two gigantopterid leaf taxa have been anatomically updated, and reconstructed together with two associated stem taxa based on their organic connection and/or anatomical similarities. Significantly, one axial taxon has been found with large vessels in

XI metaxylem and secondary xylem. Combined the morphology and anatomy of both leaves and stems, gigantopterids have been suggested as lianas, with either spines or tendrils, grown in tropical rain-forest of Permian. The occurrence of vessels seem to be resulted in a coupled structure/function co-evolution of a liana habit, although the vessels suggest gigantopterids might structurally have evolved to a level equal to that of anthophytes. On the other hand, gigantopterid reproductive organs have not been well understood. Although some potential, compressed seeds and two types of synangia have been found intimate associated or connected with gigantopterids, they still open to a further comprehensive study to determine their systematic position.

Geographically, the concepts of Gigantopteris flora and Cathaysia flora have been replaced with the Gigantopterid Biome and Cathaysia Region, respectively.

Permian geography has been reconstructed, and possible migration pathways of gigantopterids from Asia to North America have also been discussed, based upon the plant megafossil data.

Xll CHAPTER I

INTRODUCTION

There were four principal floras in the world during the Late Carboniferous and Permian. They include the Angara, Gondwana, Euramerica, and Cathaysia floras. The first two were separated into the northern and southern hemispheres, while the latter two occurred in the west and east equatorial regions respectively.

The Cathaysia Flora occupied China, Japan, Korea, and other Southeastern Asian countries. This flora is commonly referred as the Gigantopteris flora since it is characterized by gigantopterids during the Permian. This Cathaysian flora has been phytogeographically divided into the Cathaysian Southern and Northern Subprovinces

(Li, X., 1986). Since some Early Permian plants from Texas and Oklahoma have also been described as gigantopterids, the southwestern North American flora is also called the Gigantopteris flora (Halle, 1935,1937b). Li, X. (1986) simply assigned this

American flora into the Cathaysian North America Subprovince and classified it under the Cathaysian Province. However, the phytogeographical relationship between the Gigantopteris floras of the two continents has not been well understood.

Gigantopterids are a group of plants that appear similar to angiosperms in their broad leaves with reticulate venation. This group existed from the Early

Permian to the close of the period, and even survived into the Early Triassic in Yunnan and Tibet, China (Yao, 1978; Ouyang and Li, 1980). The first gigantopterid specimens were collected by F. v. Richthofen in 1870 from a coal mine four kilometers east of the Lui-pa-kou Village, in the Lui-Ho River region, Hunan

Province, China (Schenk, 1883). More recently, the village name has been verified as the Ni-Ba-Kou in Yong-Xing County (Yao, 1983b). The specimens were described by Schenk (1883) as Megalopteris nicotianaefolia, since the fossils look like leaves of cultured tobacco. The generic name was penciled in as Gigantopteris by

Schenk (Potonié, 1902), since the generic name Megalopteris has been used earlier by Dawson (1871). G. nicotianaefolia was described by Schenk (1883) as broad ovate-lanceolate leaves with smooth or undulated margins. The primary vein was thick with furrows that distally became finer. Secondary veins extended out at acute angles, obliquely ascended and arched. Tertiary veins anastomosed obliquely (Fig.

33). His description and illustration did not provide further details on the reticulate venation pattern, and this led to subsequent confusion on the definition and identification of both the genus and species.

A piece of fossil leaf with reticulate venation was collected from a coal mine of Yunnan Province, and it was identified as G. nicotianaefolia (Fig. 9; Zeiller, 1907).

However, unlike Schenk’s specimens, this specimen has the sutural veins between the secondary veins. White (1912) reported several large leaves with forked midribs, sutural veins and areolate venation from the Permian "red beds" of Oklahoma and

Texas (Figs. 10, 11). He named them G. americana, because he believed these

American specimens were congeneric with Zeiller's leaf fragment from Yunnan, although he found the sutural vein was incompatible with Schenk’s material. At this

point, the definitions of the genus Gigantopteris and the species G. nicotianaefolia

became confused relative to leaf venation. Since that time, many more specimens

collected from the Sichuan, Fujian, Shandong, Anhui, and Shanxi Provinces, and

northeastern China were assigned to G. nicotianaefolia or its congeneric species

(Yabe, 1917; Halle, 1927). Five species were reported from Korea (Kodaira, 1930;

Kawasaki, 1932, 1934; Kawasaki and Kon'no, 1933), and two from Sumatra

(Jongmans, 1935; Jongmans and Gothan, 1935). By 1935, twelve species were

included in the genus Gigantopteris, subsequently they are commonly called

gigantopterids.

A major revision was presented by Koidzumi (1936) who established the

Gigantopteridaceae with five subfamilies. He retained some species in Gigantopteris

under the subfamily Gigantopteridieae, but moved seven species from the genus to

seven newly established genera in four other subfamilies (Table 1). For example, the

G. nicotianaefolia described by Zeiller (1907) was moved into Zeilleropteris yunnanensis, and White's G. americana was put in Gigantopteridiiim americanum.

The above two examples, and the two taxa from Sumatra, were excluded from

the Gigantopteridaceae when Asama (1959) revised Koidzumi's classification. Only

two of Koidzumi's subfamilies were retained in the family, but three seed fern taxa

(Emplectopteris triangularis, Emplectopteridium alatiim, and Konnoa penchihuensis) were added to the family, because he believed the gigantopterids evolved from those

seed ferns in three evolutionary series, each beginning from one seed fern (Table 2). Asama's classification has not been widely accepted. For example, Gu and

Zhi (1974) did not include the three pteridosperm taxa in the gigantopterids, while

Mamay (1986) still retains Gigantopteridiiim americanum and Zeilleropteris in the

group. More recently, the gigantopterids have been proposed as an order,

Gigantopteridales, but without giving a classification (Li, X. and Yao, 1983; Taylor

and Taylor, 1993). To date, at least forty gigantopterid taxa have been reported

from China and other Southeastern Asian countries, and six taxa from southwestern

North America (Table 3; Li, H. et al., 1994c). Even Fiircula from the Rhaetic of

Greenland has been related to the gigantopterids by Meyen (1987). Therefore,

Gigantopteridales or gigantopterids are a very loosely defined group of plants, even

without an updated classification.

Morphologically, gigantopterids are a group of plants characterized by large

simple or pinnately compound leaves with reticulate venation (see Chapter III).

Some gigantopterid plants bear spines, thorns, and tendril-like or hook-like

structures. These plants are considered to be climbers that grew in tropical regions

(Halle, 1929; Yao, 1983a; Yang, 1987; Li, H. and Tian, 1990; Li, H. et al., 1994c).

In terms of systematic affinities, gigantopterids have been treated as different

groups. Schenk (1883) regarded gigantopterids as true ferns. White (1912)

considered G. americanum a seed fern, since it was associated with some dispersed

seeds, but he did not give further information about the seeds. Halle (1927) and

Asama (1959) also treated the gigantopterids as seed ferns, because they believed the large gigantopterid leaves were fused by the small pinnules of some seed ferns (e.g., E. triangularis). However, they were unable to demonstrate the existence of seeds.

With such uncertainty, Gu and Zhi (1974) assigned gigantopterids to a mixed group

of the Filices et Pteridospermopsida. Li, X. and Yao (1983) reported some seed-

bearing and synangium-bearing gigantopterid fronds and again classified these plants

as seed ferns, although the connection between the seed bearing frond and the vegetative gigantopterid leaves is uncertain (see Chapter VI). Mamay et al. (1988)

reported that the foliar morphology and anatomy of a Texan gigantopterid, Delnortea abbottiae, bore a close comparison with modern Gnetum. Many gigantopterid leaves,

especially those large, simple leaves with compound mesh venation, greatly resemble the leaves of certain angiosperms and modern Gnetum. For this reason, Asama

(1974, 1975, 1988a) suggested that the simple-leafed gigantopterids might be ancestral to the angiosperms. Therefore, it is still uncertain to which major group or groups of vascular plants the gigantopterids belong because of insufficient anatomical and reproductive evidence.

Although gigantopterids have been known since 1883, the study of this group has lagged behind other major vascular plant groups for several reasons. First, the study of gigantopterids was hampered by the limited material, since no structurally preserved specimens had been found until a few recent reports on foliar anatomy

(Mamay et al., 1988; Li, H. and Tian, 1990; Guo et al., 1993; Li, H. et al., 1994c).

Second, although most previous research concentrated on the description of leaf morphology, many of the studies were so simple that they slowed subsequent study.

For example, the overly simplified original description of G. nicotianaefolia even caused confusion in the generic and specific definitions (Yao, 1983b). Third, language differences slowed the communication with western scientists. Most gigantopterids have been reported from China, but many of them are published only in Chinese, or with a short abstract in English. Because of this communication barrier, new studies of gigantopterids have not been widely appreciated.

As noted above, a few studies provided leaf anatomy of Asian gigantopterids

(Li, H. and Tian, 1990; Guo et al., 1993; Li, H. et al., 1994c) and American gigantopterids (Mamay et al., 1988), but the morphology and anatomy of gigantopterid stems and reproductive organs are far from being well understood.

Fortunately, I have collected some gigantopterid materials including impressions, compressions, and permineralizations from the Upper Permian, western Guizhou

Province, China. The permineralized materials include many gigantopterid leaves and stems, and they are associated with many isolated reproductive organs (synangia and seeds). These materials have provided morphologic and anatomic details that now make a more comprehensive study on gigantopterids possible.

Objectives -- This dissertation includes: the identification and description of gigantopterid materials from Guizhou; reconstructions of various plant organs based on their morphological and anatomical characteristics; and comparisons of the gigantopterids with other groups in an attempt to clarify their systematic status. It also includes a discussion on the paleoecology and phytogeography of gigantopterids.

The objectives of this dissertation are the following: (1) To describe the morphology of new gigantopterid leaf types and summarize the architecture of gigantopterid leaves; to underscore the anatomy of some gigantopterid leaves; and to combine the morphology and anatomy to analyze leaf physiology and habitats.

(2) To describe the morphology and anatomy of gigantopterid stems; to determine the mutual relationships between the stems and leaves based on their association and anatomical similarities; and to discuss the evolutionary significance of these vegetative parts.

(3) To describe and examine the potential reproductive organs of gigantopterids, including their associated seeds and synangia. To suggest the systematic affinity of gigantopterids based on comparison with other seed-bearing and synangium-bearing plants of the same flora or other contemporaneous floras.

(4) To reconstruct detached gigantopterid organs together in order to elucidate the ecological habits and comment on the physiology of the gigantopterids.

To compare gigantopterids with other plant groups comprehensively based on the reconstructions in order to evaluate the possible role this group played in plant evolution.

(5) To summarize the phytogeographic distribution of gigantopterids, to clarify the Cathaysia and Gigantopteris floras; to reclassify these floras phytogeographically; and to interpret the floristic relationships between the local floras and the Paleozoic global floras. CHAPTER II

MATERIALS AND METHODS

Research history of the region - The fossil specimens used in this dissertation

were collected from the Laoyingshan, Dahebian, and Wangjiazhai coal mines of

Shuicheng County, and the Yueliangtian coal mine of Panxian County, western

Guizhou Province, China (Figs. 1-2). The industrial development in this area

prompted some geological investigation and paleobotanical research in the coal-field

since 1930-40's. Fossil plants were briefly listed in most geological investigation

reports. However, there were no detailed paleobotanical studies until Tian (1979,

1985) found the first Chinese coal balls from the Wangjiazhai Mine. Zhao et al.

(1980) reported a Late Permian flora from western Guizhou and eastern Yunnan, which listed 86 megafossil species, including 40 newly described taxa. Tian and

Zhang (1980) published a Permian fossil atlas of the Wangjiazhai Mine region,

including the results of their preliminary studies on coal balls. Since that time,

additional structurally preserved plants have been reported from the region (Li, Z -

M., 1983, 1986a, 1986b, 1991, 1993a; Guo, 1984, 1987; Guo and Li, H., 1984; Li, H.,

1985, 1988; Gu, 1988; Chang, 1989; Zhao, H., 1990, Li, H. and Tian, 1990; Guo et

al., 1990, 1993; Tian and Li, H., 1992; Tian et al., 1984a, 1984b, 1985, 1986a, 1986b,

1987a, 1987b, 1988a, 1988b; Hu, T , 1993; Li, H. et al., 1994a, 1994b, 1994c). Geographic Occurrence - Western Guizhou lies in the Yun-Gui Plateau and

is the major area of the Yun-Gui-Chuan coal field that is distributed in eastern

Yunnan, western Guizhou, and southern Sichuan Provinces. This coal field has its

largest coal storage and production in the Liu-Pan-Shui District (including Liuzhi,

Shuicheng, and Panxian counties) in western Guizhou (Fig. 1). Shuicheng City is

located at 104°53'E, 25°35'N. The Laoyingshan mine is about 20 kilometers east of

Shuicheng City, while the Dahebian and Wangjiazhai mines are about 10 kilometers

north and 20 kilometers northwest of the city, respectively. The Yueliangtian mine

is about 100 kilometers southwest from Shuicheng City (Fig. 2).

Geological setting and depositional environment -- Geologically, western

Guizhou belongs to the Yangtze Block (= South China Block; Fig. 1) which covers most of South China. The west part of this block is called the Kang-Dian Terra, named after the short names of Sichuan and Yunnan Provinces. During the Late

Permian, Shuicheng-Panxian lay between the Terra on the west and the Gui-Qian

Sea on the east, and deposition alternated between marine and terrestrial (Fig. 3).

From the Laoyingshan to Wangjiazhai, coal seams occur higher and higher stratigraphically, as the Gui-Qian sea transgressed westward. In the same direction, limestone deposition decreased, but terrestrial mudstone and sandstone increased

(Figs. 3-4). The Yueliangtian area to the southwest (Fig. 2) was basically terrestrial, and exhibited thinner coal seams and less limestone (Figs. 3-4).

Stratigraphically, the Upper Permian in Shuicheng is exposed in several synclines. The Laoyingshan mine is located in the Xiaohebian Syncline, while the Dahebian and Wangjiazhai mines in the Dahebian Syncline (Fig. 2). Both synclines have a similar lithology except for more limestone in the former. Four formations exposed at the Dahebian Syncline include (from base to top) the Upper Permian

Emeishan, Longtan (= Lungtan), and Wangjiazhai formations, and the Lower

Triassic Feixianguan Formation (Fig. 4; Table 4).

At Wangjiazhai, the coal-bearing terrestrial strata of the Emeishan Formation are sandwiched between two layers of basalt. The Longtan Formation contains numerous sedimentary sequences cycling from fine calcareous sandstone or limestone to silt, clay mudstone and coal. The calcareous sandstone and limestone sometimes contain permineralized fossil plants, while the mudstone contains abundant impression and compression specimens. A small number of coal balls were found in some coal seams. The Wangjiazhai Formation was established by Tian and Zhang

(1980) as a series of terrestrial deposits bearing numerous plant megafossils, separated by thin strata of muddy limestone containing marine animal fossils. The top of the formation is a two-meter thick coal seam containing abundant calcareous coal balls. The top of the seam is the bottom of the Feixianguan Formation (Lower

Triassic), which is a thick layer of gray-green fine calcareous sandstone. A standard index fossil for the base of the Triassic, the marine bivalve Claraia wangi, as well as other characteristic Lower Triassic marine fossils, are often found in the top sandstone. Therefore, this coal seam represents the highest layer of the Permian at this site (Fig. 4). At the Yueliangtian mine the Upper Permian sediments are exposed in the west wing, with a south-north strike direction, of a large syncline (Fig.

10 2). Tlie Lower and Upper Xuanwei formations are considered to be equivalent to

the Longtan and Wangjiazhai formations (Fig. 4; Table 4).

Chronologically, both the Wangjiazhai and Upper Xuanwei formations were

deposited during the Changxingian Age, and both the Longtan and Lower Xuanwei

formations during the Longtanian Age. The Emeishan Formation, especially its

upper part, is generally considered to be early Longtanian (Table 4).

Components of the flora - About 200 species of fossil plants have been

reported from the Upper Permian of western Guizhou. They include algae,

lycopods, sphenopsids, pecopterids, neuropterids, ale th opter ids, taeniopterids,

gigantopterids, ginkgophytes, conifers, and cycads (Tian and Zhang, 1980; Zhao et

al., 1980; Tian et al., 1990). These plants were sorted by Tian et al. (1990) into two

assemblage zones. Zone A and B. The Zone A includes four subzones, a-d (Table

5). The terrestrial part of the Emeishan Formation has some fossil plants, including

Gigantopterisdictyophylloides,Pecopterissahnii, Rajahia rigida (Tian and Zhang, 1980).

These plants suggest a lower part of subzone a of Zone A.

Gigantopterids of this region are more highly derived than those of Early

Permian found from other places. G. dictyophylloides with compound reticulate venation occurred throughout the Late Permian (Tian et al., 1990). Quantitatively, gigantopterids have been found to make up 84% of plant-bearing layers (Yao,

1983a). Among these layers, gigantopterids were often solely packed together into

some sublayers, or mixed with very few other plant leaves, such as Pecopteris or

Fascipteris.

11 Preservation and preparation methods - The specimens used in this dissertation display three modes of preseivation: permineralization, compression, and impression. Some permineralized specimens were collected from rocks newly washed out along some deeply cut streams, as well as from underground mining channels.

Most specimens were picked up from the waste rock piles. All mines are set up in the areas of the Upper Permian synclines (Fig. 2), and all coal mining activities are confined between the hard basalt of the Emeishan Formation and the hard sandstone of the Feixianguan Formation (Fig. 4, Table 4). Therefore, there is no doubt that all of these waste rocks were mined from the Upper Permian. Some rocks with remarkable thickness, color, and texture, even can be easily matched up with their original strata, although this is usually difficult for most broken rocks.

The permineralized specimens were prepared by the standard cellulose acetate peel technique and portions mounted on microscope slides (Phillips, 1976). Slides were observed under both dissecting and compound microscopes. Some structures were examined under SEM (Scanning Electron Microscopy). The SEM samples were prepared by cutting peels with selected structures into small pieces and mounting them on standard SEM stubs. They can also be prepared by isolating small pieces of the rock containing the specimen, etching with 1% hydrochloric acid for 1 minute or longer, and rinsing, drying, and mounting on standard stubs.

To expose and verify some structures, especially the possible attachments of some seeds, delicate dégagément was executed on compression and impression specimens with dissecting needles and razor blades under dissecting microscope.

12 Some diagrams were based on serial peels and drawn with camera lucida

attached to a Wild Heerbrugg dissecting microscope. Some images were scanned

directly into the computer from peels, slides, or specimens with ScanMaker IIG, and

were modified Using ImageStart prior to printing. Some line-drawings were also

based on such prints. All specimens were photographed with a Zeiss Ultraphot or

a Polaroid MP-3 Land Camera.

Specimens -- One specimen (D-2) of Gigantonoclea guizhouensis collected

from the Dahebian Mine, and its several slides are housed in the Beijing Graduate

School, China University of Mining and Technology, Beijing, China. Other

specimens, slides, and films used in this dissertation are held at the department of

biology, Indiana University Southeast. All specimens used in this dissertation are

listed in Tables 6 and 7.

Some specimens loaned from the Swedish Museum of Natural History were also photographed and illustrated to display additional gigantopterid features. These were collected from Taiyuan, Shanxi Province, China by Nor in and had been studied by Halle (1927, 1929).

13 CHAPTER III

GIGANTOPTERID LEAF ARCHITECTURE

ABSTRACT

Gigantopterids are a plant group mainly established from some Permian fossil leaves, and have been studied since 1883. However, there is no comprehensive study that addresses the architecture of gigantopterid leaves, and many leaf morphologies of this group have not been noted. This chapter summarized the gigantopterid leaf architecture based on previous work and new collections. Gigantopterid leaves range from very small to very large, from compound to simple, from asymmetric to symmetric, from toothed to entire. Their higher order veins vary from simply anastomosed to complicatedly netted. All gigantopterids are sorted into two leaf patterns, based on their major veins. One is pinnate pattern that includes all previously reported gigantopterids, and this pattern can be further divided into C-,

E-, and G-Types. Another is a newly recognized, actinodromous pattern that includes trinerved and quinquenerved types. In pinnate gigantopterids, some are similar to Paleozoic seed ferns, some resemble both Gnetum and angiosperms.

However, the actinodromous pattern can be morphologically comparable to that of angiosperms only. Therefore, gigantopterids are suggested to be polyphyletic.

14 INTRODUCTION

Gigantopterids are a group of plants that dominated the Cathaysian flora during the Permian and the earliest Triassic (Yao, 1978; Ouyang and Li, 1980), plus a few taxa reported from the Lower Permian of southwestern North America (White,

1912; Read and Mamay, 1964). The most striking feature of gigantopterids is their broad leaves with reticulate venation.

To date, more than 40 gigantopterid taxa have been reported (Table 3), but they have not been comprehensively summarized. In order to establish a base for future comparative studies, this chapter presents an outline of gigantopterid leaf architecture. This summary is based on previously published material as well as new collections. Some gigantopterid taxa may be taxonomically invalid, since their description and publication did not follow the requirements of the International

Code of Botanical Nomenclature {e.g., only in Chinese, without assignment of type specimens). However, no attempt will be made here to correct the nomenclature, since only leaf architectures will be considered. Although earlier workers used various terms to describe vein orders and other features, this work will utilize terminology of Hickey (1973, 1979) and Dilcher (1974), plus additional specialized terms.

Many of the line drawings are based on specimens and photos, including some specimens loaned from the Swedish Museum of Natural History. Some are redrawn or modified from previous publications (see picture caption for sources). These are used to demonstrate the variety of leaf characters found in the gigantopterids.

15 LEAF OUTLINE

Gigantopterids include both simple and compound leaf types. However, most gigantopterid leaves are large and therefore are often not collected in their entirety.

In general, it is hard to determine whether a gigantopterid lamina represents a simple leaf or a leaflet. Therefore, following the examples of Hickey (1973) and

Dilcher (1974), all gigantopterid leaves will be simply treated as laminae in this section.

1. General Morphology

To date, both petiolate (Fig. 30) and sessile laminae (e.g., some leaflets in

Figs. 22,24, 32) are known. Gigantopterid leaves vary in laminar length from about

2 cm to about 40 cm. The laminar area mostly ranges from microphyll (2.25-20.25 cm^) and mesophyll (20.25-182.25 cm^) to macrophyll (182.25-1640.25 cm^). There are also a few nanophylls (smaller than 0.25-2.25 cm^) and megaphylls (larger than

1640.25 cm^).

Many gigantopterid laminae are symmetrical about the main vein (e.g., Figs.

19, 27, 34, 38), but some are bent to one side, and usually one side is wider than the other (Figs. 25,30,37, 44). Some laminae show bilaterally symmetry distally, but the bases are not; commonly the lower basal side is downward extended (e.g., the pinnae in the upper part of Fig. 32).

16 There are various lamina forms. The oblong type includes lorate (Fig. 7), narrow oblong (Fig. 27), and oblong (Fig. 19) subtypes. Elliptic types include narrow elliptic (Fig. 34) and elliptic subtypes. Ovate types range from narrow ovate, wide ovate (Fig. 30), to very wide ovate (Figs. 26, 39-40). Obovate types range from oblanceolate to wide obovate (Fig. 29). Some laminae are round in shape (Figs. 37-

38).

Apex shapes arrange from attenuate (Fig. 28), acute (Figs. 25,27,30,32 lower laminae), obtuse (Fig. 34), and rounded (Figs. 38-39). Most bases fall into five types: normal acute, normal obtuse (Figs. 12, 27), rounded (Fig. 26), auriculate (Fig. 30), and cordate (Figs. 37-40).

2. Margin

Gigantopterid leaf margins include various types, such as lobed (upper parts in Figs. 19, 31,32), toothed (Figs. 26, 29,40), crenate smoothly rounded (Figs. 7,15,

27), and entire (Figs. 24, 33, 34, 35). The toothed type can be further divided into simple dentate (Fig. 12), simple serrate (Figs. 26, 28, 43, 45-46), compound serrate

(Fig. 29), and compound rounded (Fig. 40, 58, 67 top). The toothed margin can have rounded (Figs. 43 left top) or angular sinuses (Figs. 25, 28, 36).

Usually, simple serrate leaves have secondary veins extended into the teeth, and disappeared toward the tooth tips (Figs. 43, 64). A secondary vein can give 2-3 even more pairs of tertiaries veins in the tooth (Fig. 43,73). Their vein lets will meet some marginal veins and fimbrial veins in tooth margin (Figs. 73, 78-79). However, some taxa do not extend their secondaries into the teeth. For example,

17 Neogigantopteridium spinifenim (Yang, 1987) has secondaries broken down before entering into the teeth, while Gigantonoclea crassinervis has their thick secondaries suddenly disappeared at a distance from the shallow round toothed margin. For compound toothed leaves, secondaries extend towards the major-tootli tips, while the tertiaries taper toward the minor-tooth tips (Figs. 58, 60, 67). The tertiaries can diverge several lower vein orders to form compound networks (Figs. 58, 60 arrowhead).

3. Texture

G. guizhouensis, known from permineralized forms, is about 110-140/xm thick, and the mesophyll appears to consist mostly of spongy cells (Figs. 83-85). This lamina could be classified as the membranaceous type. On the other hand, many gigantopterid laminae (Figs. 23, 24, 34) are preserved as relatively thick carbon sheets, and only their lower vein orders can be seen. These leaves look leathery, thick and stiff, and they are probably coriaceous. Many permineralized laminar pieces have been found thicker than 200 pm, with one or two layers of palisade tissues (Fig. 100). They may belong to the chartaceous type.

4. Secretory structures

Some gigantopterid leaves have uniseriate trichomes on the lower surface

(Fig. 84), which may represent secretory glands. Some species have 0-4 black dots in each areole (Figs. 74, 77). These black dots have been proved to be internal secretory cavities, commonly about 120-200 pm in diameter, embedded in mesophyll cells (Figs. 20, 75-76, 83-84; Li et al., 1994c).

18 5. Venation

Almost all previously reported gigantopterids have their pinnate secondaries diverged from a single primary vein (midrib). According to the classification of

Hickey (1973) and Dilcher (1974), this kind of venation should belong to the pinnate venation type. However, Gu and Zhi (1974) classified gigantopterids into the pinnate and reticulate venation types, based on the ultimate 2 or 3 orders of veins instead of the first two vein orders. Thus, these two classifications define pinnate venation type differently.

Pinnate venation pattern - For this reason, the pinnate venation type of the former classification is here adapted as the pinnate venation pattern. The pinnate venation type of Gu and Zhi (1974) will be termed as C-Type gigantopterid venation, since it is typical of Cathaysiopteris. The reticulate venation type will be referred to as the G-Type after Gigantonoclea and Gigantopteris. These two types and a third

E-Type (see below) belong to the pinnate venation pattern (Table 8).

The C-Type venation is characterized by dense pinnate ultimate veins that divide dichotomously 1 or 2 times (Fig. 8). The ultimate veins from adjacent secondaries meet together to form a sutural vein (Figs. 8, 16) that intercepts the branching veinlets to form long narrow nets. A few of long narrow nets also can be formed by branching veinlets only, without the sutural vein being involved.

Companion meshes may also be formed, bilaterally along the primary vein, by the branching veinlets (Fig. 8). In addition to Cathaysiopteris, this type of venation can be also found in G. americana from Texas (Figs. 10-11) and Cathaysiopteridiiim Li

19 (Figs. 12-14) from Fujian Province, China (Huang et al., 1990). The former is a forked leaf type, while the latter seems to be a simple leaf type and has much longer

secondaries than those of Cathaysiopteris and Gigantopteridium. The American

Zeilleropteris wattii (Figs. 5, 6) and Chinese Z. yimnanensis (Fig. 9) have roughly

similar venation. Their ultimate veins generally dichotomize only once or twice before they meet the sutural veins. The secondaries of Z. wattii are very long and

thus resemble those of Cathaysiopteridiiim. However, nets of Zeilleropteris can be formed by the veinlets themselves or by jointing with sutural veins, and all nets are shorter.

The G-Type venation is characterized by anastomosing of the ultimate veins and veinlets (Gu and Zhi, 1974). This type can be further divided into two subtypes, simple and compound. The former is typical of Gigantonoclea, while the latter is characterized in Gigantopteris. In the simple reticulate sub-type, the nets are formed by roughly the same thick ultimate veins and/or veinlets. The veins of the next lower order are pinnate and do not anastomose into networks. The netted veins may be tertiaries (Figs. 17, 20, 48), quaternaries (Figs. 18, 21), or quinternary (e.g.,

Gigantonoclea taiyuanensis, in Gu and Zhi, 1974). The ultimate veins branch at narrow angles. The nets are more or less elongated triangular or polygonal, and the ratio of the net length to width varies from 3:1 to about 1:1 in different species.

Companion meshes are commonly distributed along the edge of the lower orders of veins (Figs. 17-18, 20-21, 73). Some species have one to four dark spots, which represent secretory cavities (Fig. 83-84; Li, H. et al., 1994c), in each areole (Figs. 20,

20 74-77). Occasionally, some freely ending veinlets can be found (Fig. 73). Some species have one or two orders of zigzag-shaped sutural veins between secondaries

(Figs. 17, 73, 77). Marginal veins and fimbrial veins can also be found in some species (Figs. 73, 78-79).

The compound mesh venation sub-type consists of at least two order meshes.

The large networks are formed by the lower order veins, and each network encloses several small nets that are formed by ultimate veins or veinlets. The netted veins branch at narrow to right angles. Most nets are isometrically polygonal (Figs. 41, 58,

60-61, 63) and each net can have simple or branched freely ending veinlets (Figs. 41,

93-94). G. nicotianaefolia has relatively long triangular and polygonal meshes, companion meshes along secondaries (Fig. 71), and even marginal vein-loops formed by several different orders of veins (Figs. 35, 49).

Yang (1987) established a new gigantopterid genus Progigantopteris, which is characterized by a venation type intermediate between the simple and compound mesh types. This leaf has indistinct large networks formed by branching tertiaries and the small nets of ultimate veins. It has companion meshes along the primary and secondary veins (Yang, 1987).

In addition to the above C- and G-Types, some gigantopterids have different venation. Neogigantopteridium (Yang, 1987) and Gigantonoclea crassinevis (Liang,

1988) have prominent secondaries, with some forked distally. Prominent secondary veins are also demonstrated in many American gigantopterids, such as Delnortea

(Mamay et al., 1988) and Evolsonia (Mamay, 1989) which have been described as

21 having “herringbone” secondaries and tertiaries. These American taxa have quaternaries that divide dichotomously 1-2 times and do not strongly anastomose, their sutural veins are ambiguous or nonexistent. These features may suggest a third venation type, which includes the above two Chinese and the two American gigantopterid taxa. For convenience, this group can be temporarily called E-Type

(Table 8) after Evolsonia Mamay (1989). With well preserved materials, the E-Type plants may be re-classified into different types in future studies.

Actinodromous venation pattern — A cordate-shaped leaf (Figs. 38, 68) was

described as Gigantopteris cordata by Tian and Zhang (1980) because of its compound mesh venation and heart-shaped base. However, the leaf is actually an actinodromous type with at least three primaries. Since the first pair of lateral veins are roughly equal in thickness to the midrib, they should be considered primaries, according to Hickey (1973). This newly recognized gigantopterid venation type is here considered as the second venation pattern (Table 8).

I have found many similar actinodromous leaves (Figs. 57, 59, 60, 62, 64, 68-

70); some of them exhibit five primary veins (Fig. 39, 70). Tliese leaves are usually very large and rarely collected entire (Fig. 62, 69). Based on field observations of entire leaves and collections of partial leaves, these actinodromous leaves generally have lateral or basal primaries which gradually bending distally directed toward the leaf apex. Both trineived (of three primaries) and quinquenerved (of five primaries) types have been observed. Both can be further roughly divided into two subtypes, according to whether the middle primary vein has 5-6 pairs or 10-12 pairs of

22 secondaries. Each of the remaining primaries has 5-6 or 10-12 descending

secondaries, but has about twice as many ascending secondaries. The ascending

secondaries and tertiaries are commonly thin and short, while descending secondaries

and tertiaries are generally thicker and longer, with the lowest descending ones being

the thickest and longest.

Actinodromous pattern can also be considered as a type that a middle rib

bears dimorphic lateral veins, because the basal lateral veins are different from other

lateral veins in the following aspects. First, the basal lateral veins bear ascending veins about twice as those descending veins; while other lateral veins in most leaves

bear about the same number of ascending and descending veins. Second, the basal

lateral veins bear descending veins usually longer than those ascending veins; while

other lateral veins give off both ascending and descending veins in the similar length.

Third, basal lateral veins are thicker and longer than others lateral veins, and close

to the thickness of the middle rib, that is why they can be treated as primaries.

Fourth, the basal primaries can diverge from the middle vein at widest angles, even

beyond 90 degrees; while other lateral veins branch out at angles mostly less than 80

degrees. Fifth, the basal primaries are usually much forward curved than other

lateral veins.

Without observing entire specimens of actinodromous leaves, it would be hard

to recognize the leaf shape from a broken piece. For example, a broken leaf

fragment with a curved major vein bearing numerous secondaries (Fig. 72) was

illustrated and identified as G. nicotianaefolia by Schenk (1883). Considering the

23 diagram, Zeiller (1907) suggested the entire leaf would be a pedate fern leaf similar

to that of genus Clathropteris. Now, with the above summarized dimorphic features,

it is easy to recognize the broken foliar piece as an area of a right lateral primary

vein of an actinodromous leaf. The vein has about the half number of descending

secondaries on the convex (lower) side as the ascending ones on the concave (upper)

side.

Similarly, another large broken leaf, without margin, shows an arch major vein

bearing more secondaries on one side than on the other side (Fig. 66). Therefore,

this arch major vein may be also a basal primary vein of an actinodromous leaf.

However, the venation of this actinodromous leaf appears to be simply reticulated, while other actinodromous gigantopterids have compound meshes. If based on the

classification of Gu and Zhi (1974), they should be identified to either Gigantonoclea

or Gigantopteris. However, since the actinodromous pattern has been treated as a major venation type by Hickey (1973) and Dilcher (1974), these actinodromous gigantopterids have been separated from the pinnately veined Gigantonoclea and

Gigantopteris and treated as a major venation pattern, the Actinodromous Pattern.

This pattern can been divided into trinerved and quinquenerved.

In summary, venation types of gigantopterids can be classified into two patterns, based on major veins (primary and secondaries), pinnate and actinodromous (Table 8). The former includes three types (C-, E-, and G-Types), with the G-type divided into two (simple and compound mesh) subtypes.

Actinodromous leaves have two types, trinerved and quinquenerved. The trinerved

24 includes both simple mesh and compound mesh venation types, while the latter appears with compound mesh venation only.

6. Leaf Modifications

Gigantopterids have been reported with stem modifications, e.g., thorns (Yang,

1987), and leaf modifications which include hook-like structures (Figs. 67 top, 108-

109) on stems and spines on both midribs (Figs. 73, 92) and stems (Figs. 53-55, 102-

103,105-106,110-111,119-120,126-127). Some appendages on a gigantopterid stem are recognized as tendril-like structures (Fig. 134), which may be a type of leaf modification also.

Hook-like structures - Halle (1927) reported some pinnate branch-like structures, which consists of only cylindrical, hook-like branches, but no laminae. He explained the whole pinnate branch-like structure as a hook structure modified from a gigantopterid frond. To support his interpretation, he illustrated a specimen with a much reduced lamina, but no hooks, as a transitional type between a normal gigantopterid leaf and a hook structure. Later, Halle (1929) replaced the transitional type with another specimen which has a clear laminar area and a hook structure extended from a tertiary vein.

Similar hook-like structures have also been reported by Yao (1983a) from southern China. In my collection, both compressed and permineralized hook structures are present. The compressed hooks are also frequently found preserved together with gigantopterid leaves (Fig. 67). The hooks were often carbonized and vary from about 1 to several centimeters in length and about 1-3 mm in diameter,

25 mostly. The straight basal axes, about 3 mm wide, can branch at least twice (Fig.

108). A permineralized hook-like structure has also been found extent from a vessel- bearing gigantopterid stem (Fig. 135). The shape and size of this hook-like structure is similar to that of compression hook-like structure. It branches at least twice and its basal part is about 3 mm in diameter (Fig. 132) as measured at the lower branching point. The vascular tissues is relatively well developed in the basal part and reduced distally.

Tendril-like structure - Some gigantopterid stems bear some thinner, 300 -

500 /xm in diameter, curved tendril-like structures. They are in wart-like forms protruding from the epidermis or circular forms embedded in the surrounding sediments (Fig. 134). These tendril-like structures have been preserved with nothing inside (arrow in Fig. 137) or with many small cells and a thin hollow center in the cross-section (Fig. 109).

Spines - Spines have been found on gigantopterid stems (Fig. 53-55, 102-103,

105-107) and also on the midrib or on thick lateral veins of the leaves (Fig. 92). All these spines have no connection with vascular tissue in the veins or axes. So, they are suggested to be epidermal or corticinate and might be modified from foliar parts.

LEAF TYPES AND THEIR APPLICATION TO CLASSIFICATION

Gigantopterids include both simple and compound leaf types, the latter type including odd and even pinnate subtypes (Figs. 23-24,52). Most pinnae are opposite on the rachis (Figs. 23-24), but some are alternate (Fig. 7). Gu and Zhi (1974) used the leaf types as an important classification feature to define Cathaysiopteris and

26 Gigantonoclea as pinnately compound, and Gigantopteris as simple. They also defined Gigantonoclea on the base of simple mesh venation and Gigantopteris on compound mesh venation. This classification works for many gigantopterids, but not for all. For example, Cathaysiopteris whitei, G. americanim, and Cathaysiopteridium fasciculatim (Huang et al., 1989) have similar venation patterns, but the former is a compound leaf, while the latter two appear to be large simple leaves. Similarly,

Gigantonoclea had been defined by Gu et Zhi as compound leaves, but some species

{eg., G. colocasifolia, G. rotundifolia, Yang 1987) have been confirmed as simple leaves based on their axillary buds. On the other hand, some Gigantopteris specimens, e.g., G. nicotianaefolia (Tian and Zhang, 1980; Figs. 32, 56) have been found as pinnately compound with a terminal pinnatifid segment. Therefore, the concept of simple leaf or compound leaf can no longer be used as a generic character in classification of gigantopterids.

For future classification, leaf venation (Table 8) should serve as a key index for all gigantopterids, except for E-Type gigantopterids, which show insufficient venation details. All gigantopterids with C-Type venation can be put into a common group, including both compound and simple leaves. Because of the similarity in leaf architecture, the unique C-Type venation, may suggest some intrinsic affinities between them. All the rest of the gigantopterids have G-Type venation in either simple or compound mesh type. Since both simple and compound mesh venation types are very similar, all these G-Type gigantopterids should be systematically closer to each other than to the C-Type. Both simple and compound mesh venation types

27 can be found in both simple and compound leaves, but their major veins can be distinguished into pinnate and actinodromous patterns. The actinodromous gigantopterids are limited to simple leaves only, and appear to be more derived than all other gigantopterids. Since actinodromous gigantopterids have been found with either simple or compound mesh venation, they seem to represent a derived level in both simple and compound mesh G-Types. To reflect such a derived level, all actinodromous gigantopterids should be separated from other types and classified together at a derived level. In short, in future the classification of the gigantopterids, leaf architecture similarities should be used, since they may represent systematic relationships.

EVOLUTIONARY SIGNIFICANCE

Origin of gigantopterids - In extant angiosperms, both compound and simple leaves can be found in different taxa or both on the same plant. When occurring on the same plant, some leaves appear in intermediate patterns. Some plants have compound leaves with a large terminal segment composed of several merged pinnae; other plants have a simple leaf with pinnatipartite to pinnatisect segments. Similar intermediate types have also been found in gigantopterids. The former type was reported by Halle (1927) from Shanxi Province, China (Fig. 19), while the latter type has been found in western Guizhou (Figs. 31-32, 51, 56). These intermediate types suggest that the simple gigantopterid leaf might be the end product of fused pinnae of a compound leaf, and each pinna fused from pinnules of a compound frond.

28 Considering the fact that intermediate leaves geologically appear later than pinnate compound leaves, the simple leaves may have evolved from the pinnae of pinnate fronds. Since each ultimate second vein area of Gigantonoclea has veins more or less similar to those of a pinnule area of E. triangularis^ Halle (1927) suggested each pinna of the former taxon was merged from pinnules of the latter.

Asama (1959) developed Halle’s idea into the concept of the "segment cohesion." He believed that the small pinnules of some seed ferns cohered into the large leafed plants. He set up eight coherent series, each series started from a seed fern taxon {e.g., Emplectopteris, Emplectopteridium, Konnoa, Lonchopteris, Aipteris,

Callipteridium). The cohesion was interpreted as being the result of the climate changing from wet to dry. The same climate change caused the same trend in the evolution of the different series. Thus, he considered these series as evolutionary ones. He redefined Gigantopteridaceae to include three series named after the three initial seed fern genera {Konnoa, Emplectopteris, Emplectopteridium), with each series representing a subfamily (Table 2).

Konnoa penchihuensis in Konnoa Series has been changed into Callipteris tachingshanense by Gu and Zhi (1974). This species has venation (Gu and Zhi, 1974) similar to that of C. whitei, and both taxa have the similar long pinnae. So, there seems no argument on the possible evolutionary relationship between them. In other words, Callipteris might be the ancestral plant of the C-typed gigantopterids.

However, the Emplectopteridium Series has been debated the most. This series begin with Emplectopteridium alatum, through an unknown unicoherent plant,

29 then the bicoherent Bicoemplectopteridium (= Gigantonoclea) longifolium, to the tricoherent “G. nicotianaefolia'' (Table 2). Asama's specimens of “G. nicotianaefolia" actually belong to Gigantonoclea (see below). Since the compound mesh venation of the Gigantopteris and the simple mesh venation of Gigantonoclea are very different from those incomplete mesh venation oiEmplectopteridium, these three genera have been thought of as not in the same evolutionary series (Yao, 1983b; Li, X. and Yao,

1983; Yang (1987). However, Yang (1987) pointed out that Gigantopteris could have originated from Emplectopteris. She accepted Asama’s cohesion theory and reformed

Asama's Emplectopteris Series. She keptE. triangularis as the beginning of the series.

Meanwhile, she established a new genus Progigantopteris and inserted it between

Gigantonoclea and Gigantopteris. The new Emplectopteris Series thus extended from

Emplectopteris > Gigantonoclea -> Progigantopteris -> to Gigantopteris (Fig. 42).

Yang (1987) found Emplectopteris henanensis had pinnules partly fused (up to about half) and a venation pattern of an intermediate type between E. triangular and

Gigantonoclea. This suggests that Emplectopteris might be one of the ancestral taxa of G-typed gigantopterids.

Origin of compound mesh gigantopterids — Yang (1987) believed the transitional venation type of Progigantopteris suggested that the compound mesh G-

Type might have originated from the simple mesh G-typed gigantopterids. However, how Pro^gantopteris evolved into the two types was not clearly demonstrated. The

G. nicotianaefolia and two other Gigantopteris species were briefly mentioned and

30 illustrated (Fig. 42), but without description and photos (Yang, 1987). In other words, the origin of compound mesh gigantopterids remains unclear.

Considering my collections and previous published materials, at least three

kind of gigantopterids leaves have been found with compound meshes. One is the compound G. nicotianaefolia leaf consisting of oblong shaped pinnae (Figs. 34-35,47,

50). The second is a simple leaf in the actinodromous pattern (Figs. 38-40,57,59-60,

62, 64, 68-70, 72; Schenk, 1883; Tian and Zhang, 1980). The third type seems to be

a simple leaf with pinnate venation pattern (Fig. 36, 65). There is no clue to the origin of the last type at the present time, but the second type might be fused from the first type as evidenced by the intermediate leaves of G. nicotianaefolia (Fig. 32,

56).

Figure 49 show a part of G. nicotianaefolia leaf with compound mesh venation and entire margin. Three similar but little smaller sized foliar segments have been found associated with five separately preserved Gigantonoclea! cf. longifolia pinnae of three sizes (Fig. 47). All these laminae have identical shape and margin. Their pinnate secondaries are arranged in the same ratio in terms of their density and length to their laminar size, although tertiaries or higher ordered veins are not clearly preserved. All suggest they might belong to the same plant, but in different developmental stages. In other words, Guizhoiithecal cf. longifolia (Fig. 52) could be in the immature stage, with tertiaries and quaternaries not well developed.

It should be pointed out that this does not concur with Asama's (1959)

Emplectopteridium Series in which G. nicotianaefolia was hypothesized as having

31 originated from Gigantonoclea lon0olium. The specimens identified as G. nicotianaefolia by Asama (1959) actually are some Gigantonoclea specimens with simple meshes from Korea, Benxi (= Penchi) of Liaoning Province, and Yantai (=

Yen-tai) of Shandong Province, China. However, one specimen of G. lon^folium cited by Asama (1959) seems also to be a compound leaf with long narrow pinnae and the terminal segment was merged by several pinnae.

Significance of actinodromous leaves -- Morphologically, gigantopterids have been considered similar to angiosperms because of their broad simple leaf and mesh venation. However, both features have been debated, since both simple leaf and the compound mesh venation can be found in some extant ferns (Hetterscheid and

Hennipman, 1984), Gnetum, and angiosperms. Thus, gigantopterids might be an artificial group that was assemblaged superficially based on their broad leaves with netted venation. Some gigantopterids might be regarded at the true fern level, and some {e.g., Delnortea abbottiae) may be developed to the level of Gnetum as Mamay et al. (1988) suggested. The oblong leaves of G. nicotianaefolia (Figs. 47, 49) look like those of Gnetum. Both have entire margin, compound mesh venation, and freely ending veinlets in areoles. Therefore, it is difficult to thoroughly exclude this possible relationship between them.

Many gigantopterids with compound mesh venation are more similar to certain derived angiosperms than to Gnetum in their broad ovate to round leaf, heart-shaped leaf base, and more vein orders that diverge at wider angles than that of G. nicotianaefolia. Most actinodromous gigantopterids have been found with

32 compound mesh venation. However, a gigantopterid foliar piece appears possibly in actinodromous pattern, and it has simple mesh venation (Fig. 66). In other words, actinodromous gigantopterids appear as the most derived types in both simple and compound mesh types. This venation pattern, especially those with compound mesh venation, is the most interesting feature in terms of their systematic attribution. In extant plants, actinodromous leaf pattern has been only demonstrated in angiosperms

(L. J. Hickey 1994, personal discussion). Thus, the gigantopterids with actinodromous pattern and compound venation are the plants most resembling angiosperms. On the other hand. Gnetum does not exhibit actinodromous venation pattern. Because the basal lateral veins are not so thick as the middle vein, they are not primaries: they are really dimorphic from other lateral veins (D. W. Taylor

1996, personal discussion). At this time it is unknown whether these dimorphic lateral veins were reduced from the lateral primaries or if they are underdeveloped.

The dimorphic venation feature suggests that some of gigantopterids might be related to both gnetophytes and angiosperms.

In conclusion, gigantopterids appear to be a polyphyletic group. All C-Type gigantopterids may be systematically related, while the relationships among these E-

Type gigantopterids are unclear. On the other hand, although all gigantopterids with simple mesh or compound mesh venation may be closely related, both may have developed toward actinodromous leaf patterns separately. In those gigantopterids with compound mesh venation, simple leafed 0 . nicotianaefolia seems to be comparable to Gnetunv, while some actinodromous leaves appear to closely resemble

33 certain angiosperms. However, these conclusions are based only on leaf architecture.

Whether gigantopterids and anthophytes are homoplasious or homologous should be

tested with anatomical and reproductive features.

34 CHAPTER IV

FOLIAR ANATOMY OF GIGANTOPTERIDS

ABSTRACT

Some specimens of Gigantonoclea guizhouensis and Gigantopteris dictyophylloides from the Upper Permian of western Guizhou Province in southwest

China are permineralized and provide details of leaf anatomy. The two taxa are morphologically characterized by their simple and compound mesh venation respectively. Anatomically, both have similar hypodermal sclerenchyma ribs, endodermis, tracheids, and paracytic stomata on the abaxial surface. These similarities suggest that they are very closely related. G. guizhouensis has elongated epidermal cells with sinuous anticlinal walls, secretory cavities in the mesophyll, multicellular spines on the midrib, and U- or V-shaped xylem in the midrib and secondary veins. G. dictyophylloides, however, has isometric epidermal cells with smooth anticlinal walls, two or three layers of palisade tissue, and cordate-shaped xylem with radially arranged tracheary elements in the midrib. Both are morphologically and anatomically different from Gigantopteridium and the North

American Delnortea. Considering their anatomical features, a liana habit is suggested for both taxa.

35 INTRODUCTION

The anatomical details of Asian gigantopterids are poorly known. Yao and

Crane (1986) briefly described a stomatal type on gigantopterid leaves from the

lower Longtan Formation of the Lower Permian in Jiangsu Province, South China, without giving the taxonomic name. However, the description fits the stomatal patterns of Gigantopteridiim as depicted by Yao and Wang (1991). Permineralized gigantopterids from Guizhou Province, China, including detailed anatomy of

Gigantonoclea giiizhouensis, have revealed many interesting features (Tian et al,

1985, 1987b; Li, H. and Tian, 1990; Li, H. et a l, 1994c). Guo et al. (1993) reported foliar anatomy of Gigantonoclea lagrelii and Gigantopteris dictyophylloides. Mamay

et al. (1988) described the foliar morphology and anatomy of Delnortea abbottiae from Texas, western North America. They compared the anatomy of this taxon to that found in modern Gnetum.

This chapter presents foliar anatomy of both G. giiizhouensis and G. dictyophylloides. The former is adopted from Li, H. et al. (1994) with minor modifications. The latter is based on new material, and shows some features different from those reported by Guo et al. (1993) to some extent. The two taxa are also anatomically different from North American Delnortea and Asian

Gigantopteridiim. Subsequently, the anatomy of these gigantopterids is generally compared with other plant groups to determine their possible affinities.

36 DESCRIPTION OF GIGANTONOCLEA GUIZHOUENSIS

General morphology and leaf architecture - Gigantonoclea was established by

Koidzumi in 1936 and emended by Gu and Zhi in 1974, who described G. giiizhouensis in the same contribution. Since the generic emendation and original

specific diagnosis were in Chinese, a translation of them follows:

Gigantonoclea (Koidzumi, 1936) emend. Gu et Zhi, 1974

Leaves pinnately compound, ultimate rachis thick and

unforked; pinnules oblanceolate, oblong, or ovate with entired,

undulate, sinuous, serrate, or crenate margins, midrib relatively thick

and one to three times pinnately branched; fine veins form simple

elongate-triangular meshes; companion meshes, sutural veins, and

blind vein lets occasionally occur.

Geological occurrence: The late Early Permian to early Late Permian.

Gigantonoclea guizhouensis Gu et Zhi 1974

Pinnately compound leaves with long elliptic leaflets, each about

10 cm long by about 4 cm wide, with undulating or entire(?) margins;

midrib about 1 mm in width with twice pinnately branched lateral

veins; fine veins mainly form long, polygonal meshes; blind veinlets

absent, companion meshes not distinct, and intercostal veins seem to

occur; sutural veins occur indistinctly in the intercostal area, and

deviate toward the basal side.

37 Note: The leaf shape is similar to that of Gigantonoclea hallei

(Asama) Gu et Zhi (1974), but the latter has shorter meshes and wider

companion meshes.

Geographic and geologic occurrence; Panxian County,

Guizhou Province; Xuanwei Formation, early Late Permian.

A more detailed description of G. giiizhouensis was given for specimens from

Northern Tibet by Li, X. et al. (1982b) in Chinese. It is translated as below with modification on vein term to make them consistent with those used in Hickey (1973) and Dilcher (1974).

Specimens are segments of pinnules and, judging from Figure

2 of Plate VI, the pinnules appear to be more than 7 cm long and 4

cm wide. Distally the margin is shallowly serrated. The midrib (=

primary vein) is 1-1.5 mm wide with lateral veins that branch twice.

Secondary veins diverge at 60°-70° from the midrib, in a more or less

sub-opposite pattern, and extend into the marginal serrations. Tertiary

veins diverge at 45° from the secondary veins. Vein endings break

down cladodromously and anastomose with each other or with the

adjacent tertiary veins to form long polygonal or triangular meshes on

the basal side of the secondary veins. Intercostal veins extend out

from the midrib. Bilaterally along the sides of the lateral veins, the

companion meshes are not apparent.

38 Additional details -- The venation of the present specimens is very well preserved and identical to the description of Li, X. et al. (1982b), especially the terminal branching pattern of the tertiary veins. This confirms that the present material belongs to G. guizhouensis. The new material provides additional details to previous descriptions and clarifies the following features:

1) One foliage specimen bears a partially permineralized petiole that clearly shows an expanded base (Fig. 73), suggesting that this specimen may represent a simple leaf.

2) The leaves are elongated-elliptic with serrate margins (Fig. 73).

3) The sutural vein (Figs. 77, 73) is distinct to some extent and parallel to the secondary veins.

4) The companion meshes (Fig. 73) that occur bilaterally along the sides of the midrib and the secondary veins are well defined, but the companion meshes along the tertiary veins are less distinct.

5) No well-defined intercostal veins extend from the midrib. The basal part of the secondary vein actually departs from the midrib at such a small angle that it is often considered part of the midrib. Since the first tertiary veins depart from the basal side of this secondary vein, they often appear as if they are departing directly from the midrib. For this reason, they were described previously as intercostal veins.

6) A few freely ending veinlets (= Gu et Zhi's blind veinlets) occur within the meshes and they often connect to a dark spot on their terminal end (Figs. 73,

39 74). Each mesh encloses 0-4 of these spots. Using anatomically preserved foliage, these dark spots have now been verified to be the remains of secretory cavities (Fig.

90) in the mesophyll cells (see below).

7) Dégagément reveals that the fimbrial vein extends along the inside edge of the leaf margin (Figs. 78-79) and fuses with the terminal ends of some secondary or tertiary veins, or with the veinlets.

Anatomy and histology - Epidermal system - The thickness of the preserved lamina ranges from 110 to 140/xm (Figs. 83-85). The cuticle is thin and fragile, but can be observed on some peel preparations. Both abaxial and adaxial epidermal cells consist of two basic types based on cell shape. One is elongated, approximately

130/xm long, 20/xm wide, and 10/xm thick, and is characterized by smooth anticlinal cell walls. This cell type covers the midrib and the thicker portions of the secondary and tertiary veins, with the long axes of the cells paralleling the veins. The second type of epidermal cell is slightly wider and has undulated anticlinal walls. These cells occur over the mesophyll areas of the lamina (Fig. 80).

Stomata occur only on the abaxial epidermis, except for occasional ones on the adaxial surface over the secondary veins, where the pores parallel the veins. The orientation of stomata on the abaxial surface is irregular with a density of 40-

100/cm^ Each stomatal apparatus is paracytic with a pair of kidney-shaped guard cells, two lateral subsidiary cells, and usually a pair of polar cells. The two guard cells appear enclosed by the subsidiary cells. Outer guard cell walls are smooth and thin; the inner walls exhibit rib like thickenings that radiate from the stomatal pore.

40 Often the guard cell walls are thinner in the polar region. Each light-colored

elongated subsidiary cell, with smooth anticlinal walls, is bordered by a flanking

transitional cell with a smooth anticlinal wall adjacent to the subsidiary cell and undulated walls next to normal epidermal cells. Occasionally, one additional subsidiary cell is inserted between the subsidiary cell and the transitional cell. Polar cells are often found separately on the two polar areas. The polar cell is linked to the stomatal apparatus and contacts the ends of the two guard cells with its end wall.

Occasionally, it is perpendicular to the stomatal apparatus and contacts the ends of the two guard cells with its side wall, forming a paratetracytic stomatal type.

Sometimes, non polar cells can be found at the polar area. The stomatal pore is about 10-20 fim long and up to 4 fim wide. The diameter of the outline of the subsidiary cells ranges mostly from 50 fim to 70 /itm (Fig. 81). A single, smaller stoma (10 X 20 jim), found in an areole, may represent a younger ontogenetic stage.

Uniseriate hairs occur on the abaxial epidermis. Each is made up of three or four cells, with the basal cell about 30 /xm in diameter (Fig. 84). Short, multicellular trichomes, each about 70/xm in diameter, are also occasionally found on the abaxial surface of the lamina. These structures include cells with dark contents, perhaps of a secretory nature.

Emergences - Sharp protuberances occur along the abaxial surface of the midrib, one at each site where a secondary vein diverges. These structures are epidermal in origin and separated from the cortical cells by a layer of small, thin cells (Fig. 92). Each emergence morphologically resembles the prickles of some

41 modem members of Rosa. Prickles are generally classified as outgrowths of superficial stem tissues, while spines represent outgrowths from leaves (Benson,

1979). Thus the emergences on G. gLiizhoiiensis should be classified as spines.

In G. guizhouensis each spine ranges from 750 to 1,000 /xm long, about 500

/xm wide (at the base), and consists of two types of cells. The epidermal cells appear identical with normal epidermal cells on the midrib. The other cell type consists of large, short sclerenchyma cells, each about 100 /xm long and 40 /xm wide (Fig. 92).

The adaxial midrib surface sometimes bears smaller, shorter emergences, which consist of similar cell types, These may represent spines at an early stage of development.

Vascular system — In longitudinal section, the petiole of a single, partially permineralized specimen shows an expanded base (Fig. 73) with an abscission layer at the base. The tracheids in the petiole are the same as those in the midrib.

The midrib of G. guizhouensis is about 1-2 mm in diameter and is more expanded on the abaxial surface than on the adaxial side. In transverse section it contains a U-shaped band of xylem segments (Fig. 88) with the opening directed to the adaxial surface. Phloem is poorly preserved. Some larger secondary veins also exhibit a U- or V-shaped configuration (Fig. 89). The vascular system consists only of primary xylem. In the midrib, the xylem occurs in up to eight, fan-shaped segments, each with protoxylem along the outer edge. The segments are discontinuous, but this may represent simply poor preservation. From the midrib to the finer veins, the number of xylem segments gradually decreases; tertiary veinlets

42 have only a single group of tracheids which are circular in transverse section. From the protoxylem to the metaxylem in the midrib or a thick lateral vein, tracheary elements exhibit annular, spiral, and scalariform thickenings, transversely elongated bordered pits, and circular bordered pits, respectively (Figs. 87,91). Tracheids found in the freely ending veinlets include only two rows of short elements (35 x 40 /xm in diameter, shorter than 200 /xm) with annular thickenings. The tertiary veins contain elements with annular or spiral thickenings, while the secondary veins and the midrib contain all types of tracheids. Most tracheids exhibit helical or scalariform thickenings and range up to 50 /xm in diameter; they may be more than 1.0 mm in length. Bordered pits range from round to elliptic in shape and from 5 x 5 /xm to

5 X 10 /xm in diameter. However, the structure similar to the scalariform perforation plate reported by Li, H. and Tian (1990) has not been found in the new materials.

Ground system - The ground tissue of the leaf is variable within the lamina.

In the region of the midrib and secondary veins, the ground tissue contains a sclerified hypodermis, parenchyma, and a layer that resembles an endodermis.

Hypodermal cells appear circular in cross section, about 15-25 /xm in diameter, and are more than 200 /xm in length. They are tightly packed together in two to ten layers that form vertical ribs. Between the hypodermal ribs are parenchyma cells

(about 50 /xm in diameter) and some presumed secretory cells that often contain dark-colored materials. Internal to the sclerified hypodermis is a zone of parenchyma in which the cells are often poorly preserved or separated. This layer can be found in the midrib, secondary veins, and occasionally in tertiary veins.

43 The uniseriate endodermis consists of enlarged cells that enclose the vascular tissues in the midrib (Fig. 92). A similar layer partially encloses the vascular tissue in the secondary veins (Fig. 89). Cells are elliptical (30-50 x 70-100 /xm) in cross section and appear square or hexagonal (90-130 /xm long) in radial longitudinal section, with thickened inner tangential walls. Since no Casparian strips have been identified on the cell walls, it was previously described as a bundle sheath (Li, H. and

Tian, 1990). Here it is considered a probable endodermis for several reasons: 1) its position, 2) it encloses several vascular segments (unlike a bundle sheath, which usually encloses only one vascular bundle), and 3) the wall thickenings resemble those found in endodermal cells in older axes, which consist of thick deposits of suberin and cellulose. These are deposited on the inner tangential walls and often on the radial walls of the endodermis cells (Esau, 1965).

The ground tissue of the mesophyll consists of both palisade and spongy tissue. In transverse section, it is difficult to distinguish between these two tissue types, because the palisade cells are relatively short and similar to spongy cells in shape (Figs. 83-85). Generally, the palisade cells are rounded, measure about 25 /xm in diameter, and appear darker than the epidermal and spongy cells (Fig. 82). The spongy cells measure about 30-60 /xm in diameter and are randomly arranged.

Secretory structures - Three types of secretory structures have been identified within the ground tissue in leaves of G. guizhouensis. One type occurs in the midrib and secondary veins, where several elongated parenchyma cells are longitudinally linked and often contain dark material. Sometimes, the transverse cell walls between

44 these secretory cells are absent, thus forming an elongated structure similar to a secretory canal. The second type is a secretory cavity which occurs among the mesophyll cells. In this form, up to four cavities are enclosed by each areole. In paradermal section, the cavities measure from 120 to 200 /xm in diameter (Figs. 75,

76, 90), considerably larger than the surrounding mesophyll cells. Each cavity contains light to dark brown material and is surrounded by radially oriented spongy cells. Often the cavity occurs at the end of a freely ending veinlet. The third type is a rarely seen, delicate structure that is composed of a tracheary cell and an oval cell which ends a freely ending veinlet. The annular thickenings of this tracheary cell are modified into a funnel-like shape that appears to open into the oval, possible water storage cell, 45 x 60 fxm (Fig. 86).

DESCRIPTION OF GIGANTOPTERIS DICTYOPHYLLOIDES

General morphology and leaf architecture — The genus Gigantopteris was first established with the type speciesG. nicotianaefolia by Schenk (1883; see Chapter I).

However, since the originally illustrated pictures and description of the type species did not clearly show the venation details and the leaf margin, the species and the genus has been redefined by different authors (White, 1912; Halle, 1927; Koidzumi,

1936; Asama, 1959, Gu and Zhi, 1974, Yao, 1983b). The diagnosis of the type species was lastly emended by Yao (1983b) in English, but the last emendation of generic diagnosis was given by Gu and Zhi (1974) and it has been retained in

Chinese. In this dissertation, this generic diagnosis is adapted and translated from

Chinese and modified terminologically as follows:

45 Gigantopteris (Schenk) Gu et Zhi, 1974

Leaf large, simple, attachment unknown, obovate, oblique

cordate, rhomboid, or oblong shaped with entired, crenate, or toothed

margins; veins four orders; midrib thick, secondaries to quaternaries

pinnate; compound mesh venation consisting of large networks

formed by quaternaries enclose the small nets formed by anastomosed

veinlets; blind veinlets occur in meshes in some species. Midribs

often give off subsidiary (or intercostal) veins; reproductive organs

unknown.

Geological occurrence: The Late Permian.

G. dictyophylloides was described in Chinese by Gu and Zhi (1974). Although it has been relatively widely cited or re-studied {e.g., Zhao et al., 1980, Tian and

Zhang, 1980; Guo et al., 1992, 1993), the specific description has been retained in

Chinese. A translation is provided below:

Gigantopteris dictyophylloides Gu et Zhi, 1974

Leaf very large, shape unknown, margin with obtuse dentate to

rounded teeth; quaternaries branched and anastomosed into large

networks enclosing small nets formed by veinlets; nets regular

polygonal; blind veinlets very prominent with ends often recurved;

subsidiaries given off from midribs; companion meshes none.

46 Note: This species differs from G. nicotianaefolia in its obtuse

dentate margin, short secondaries, large intercostal distance, regular

shaped and smaller sized meshes, prominent blind veinlets, and no

companion meshes along the secondaries.

Geological and geographic occurrence: Upper Shihhotse

Formation in Mengcheng, Anhui Province; Longtan Formation in

Jiangning, Jiangsu Province and Longyan, Fujian Province; Leping

Formation in Jishui, Jiangxi Province; Xuanwei Formation in Panxian,

Guizhou Province, and in Fuyuan, Mojiang, Xuanwei, and Yanjin

counties, Yunnan.

Geological age: The early Late Permian.

Description of new material -- Since no complete leaf of this species has been reported, this species is identified by its venation and its dentate margin. The isometric compound mesh venation of G. dictyophylloides is different from the elongated compound meshes of G. nicotianaefolia, and the triple larger networks of

G. meganetes (Tian and Zhang, 1980). The simple dentate margin of the former is different from the smoothly crenate or entired margin of G. nicotianaefolia, and from the compound rounded toothed margin of G. meganetes.

Many broken gigantopterid leaves in my collections can be identified to G. dictyophylloides based on their venation type and marginal features. These specimens have quaternary veins branched and formed into large networks which are regularly arranged into isometric polygonal nets, mostly 2-3 mm in diameter. Each large

47 network encloses several small, isometric polygonal nets, mostly about 1-1.5 mm in diameter. The specimen showed in Fig. 60 is a broken leaf with typical G. dictyophylloides venation (Fig. 61). However, it has a different leaf shape and marginal teeth. The specimen has the upper and lower parts showing different venation patterns. The upper part has three secondaries preserved, the lowest secondary vein extends into a marginal tooth which is transitional between dentate and compound rounded toothed types. The top part of tooth is dentate with symmetric upper and lower slopes, but the basal parts of the both slopes have at least two small rounded teeth. Each covers the top area of a tertiary vein which extends from the secondary. The lower part of this specimen shows a broken, arching thick vein with at least twelve ascending secondaries and about six descending secondaries. The ascending ones are denser than the descending ones, but both have roughly the same thickness. This part is identical with a specimen

(Fig. 72) of G. nicotianaefolia described by Schenk (1883). However, through dégagément, it has been verified that both parts of the present specimen are connected by a laminar part in the rock. Therefore, both parts belong to a single leaf and the major vein in the lower part is a lateral primary vein. In other words, this leaf is in an actinodromous leaf pattern. Although their higher order veins are of the compound mesh type and resemble that of Gigantopteris (Chapter III), these with actinodromous venation should be treated differently, taxonomically. Since there are insufficient specimens to establish such a new taxon, this actinodromous gigantopterid is temporarily treated as G. dictyophylloides.

48 Anatomy — Similarly, some permineralized specimens are identified as G. dictyophylloides just based on their compound mesh venation. The nets are commonly isometric with simple or branched freely ending veinlets (Figs. 93-94).

The cuticle on the upper epidermis is thicker and preserved better than that on the lower epidermis. Upper epidermis consists of a single layer of polygonal cells with straight anticlinal walls. These cells are more or less isometric, with dimensions varying between 30-60 /i,m (Fig. 95). Stomata are rarely seen on the upper epidermis, and only one was found in this study (Fig. 96). This stoma is of the paracytic type and about 30 /xm in diameter. It consists of two guard cells and two subsidiary cells. The inner stomatal ledge is conspicuous but without radial thickenings. Six normal epidermal cells surround the stoma (Fig. 96). The lower epidermal cells are poorly preserved and the cell shape is unclear. However, the stomata are relatively well preserved. Stomata are paracytic and randomly distributed. Each stoma is about 50 /xm. Guard cells are sunken and each is about

10 /xm wide (Fig. 99). Mesophyll is differentiated into palisade tissue adaxially and spongy tissue abaxially. The palisade tissue consists of two or three layers of short palisade cells (Fig. 100).

A structurally preserved midrib has not been found. The cross section of secondaries exhibits a heart-shaped xylem segment surrounded by a poorly preserved endodermis. Tracheary elements are arranged in radial rows separated by parenchyma cells. The largest tracheary element is slightly larger than 45 /xm in diameter, and smaller cells are located at both inner and outer edges (Fig. 101). In

49 paradermal section of tertiary veins, the largest elements are up to 30 /im in

diameter (Figs. 97-98). Some tracheary cells have been found with annular, helical,

or reticulate thickenings, and some tracheary elements with 1-2 rows of transversely

elongated pits. Sometimes, bordered pits are also found on tracheids in secondary veins.

SYSTEMATICS

Order Gigantopteridales

Family Gigantopteridaceae

Genus Gigantonoclea (Koidzumi, 1936) emend.

Both the generic and specific diagnoses of G. guizhouensis described the leaves

as pinnately compound (Gu and Zhi, 1974). In Gu and Zhi (1974), Gigantonoclea lagrelii, G. lobata, Guizhoutheca? cf. long^folia, G. hallei (Fig. 19), and Gigantonoclea

sp. (= G . meridionalis Li, X. et al., 1982a; Fig. 22) showed clearly compound leaves, but G. guizhouensis, G. mira, G. kaipingensis, G. acuminatiloba, and G. taiyuanensis were described as having unknown foliage shape. Since the large foliar segments they illustrated lacked bases, it is uncertain whether they represented simple leaves

or pinnae of a larger compound frond. Yang (1987) described a petiole with an

axillary bud on G. colocasifolia from Henan Province in Northern China, which suggests a simple leaf (Fig. 30). Thus, the genus should be revised to include both pinnately compound and simple leaves, otherwise it should be split. In addition to that, Gu and Zhi's (1974) material of G. guizhouensis was not sufficiently preserved

50 to illustrate several features, including companion meshes, intercostal veins, and sutural veins. In the description by Li, X. et al. (1982b), the sutural vein was not mentioned, but more details were provided on other aspects of the plant, such as a description of the terminal branching pattern of the tertiary veins and the intercostal veins. Some structures, however, were still not well-known, such as the companion meshes, which were indistinct in their material. These authors used the term "lateral veins" without distinguishing between secondary and tertiary veins. My new material of G. guizhouensis is preserved with enough detail to clarify the earlier ambiguous descriptions of the species. Therefore, an emended diagnoses for Gigantonoclea and

G. guizhouensis are offered below:

Diagnosis: Foliage compound or simple leaf; rachis thick and unforked; laminar blade vary from very long elliptic to ovate in shape with varied margins; midrib relatively thick; lateral veins one to three times pinnately branched; the ultimate veins equally or unequally dichotomously branched and anastomosed into simple elongated rectangular or long triangular meshes, which occasionally enclose freely ending veinlets with or without black dots on the ends; companion meshes occur bilaterally along the midrib or higher order veins; in some species there are sutural veins between and paralleling the lateral veins; occasionally there are some species with fimbrial vein along the inside edge of the foliar margin.

Geological occurrence: The late Early Permian to the end of Permian; perhaps into the earliest Triassic.

51 Gigantonoclea guizhouensis (Gu et Zhi) emend.

Diagnosis: Compound or simple leaf; lamina elliptic, about 10 cm long and

4 cm wide, with serrated margin and enlarged petiolar base. Midrib (primary vein)

1-2 mm wide, with vertical fine ribs and basal-recurved spines on abaxial surface as well as short emergences on adaxial surface. Each spine or emergence consists of

multiple cells; extends out from the point of origin of secondary veins. Vertical fine

ribs on surface correspond to hypodermal sclerenchymatous ribs in the cortex. There

are enlarged cells in the position of endodermis with thickened inner tangential and

radial walls. These cells are elliptical, 30-50 x 70-100 p.m in cross section; in radial

longitudinal section they appear square or hexagonal, 90-130 /xm long. Central xylem

is U- or V-shaped in cross section opening to adaxial side, consisting of up to eight xylem segments, each with protoxylem along the outer edge. There are tracheids with annular and helical thickenings, or circular bordered pits. From midrib to higher order veins, number of xylem segments decreases and tracheid thickenings become simpler. Venation pinnate, secondary veins diverge at 60°-70° from the midrib, oppositely arranged in lower portion and sub-oppositely in more distal portions; they extend into marginal serra tu res. Tertiary veins diverge at 45° from the secondaries, oppositely give off two pairs of quaternary veins, and then break down cladodromously; paired quaternary veins equally or unequally dichotomously divide and anastomose into simple elongated rectangular or long triangular meshes, which enclose 0-4 black dots that correspond to secretory cavities in the mesophyll. Meshes occasionally enclose freely ending veinlets with black dots on the ends. Quaternary

52 veins dichotomously divide bilaterally along the midrib and secondary veins, forming companion meshes with the opposite quaternary veins. The cladodromously ending quaternary veins anastomose to form long triangular meshes, which fuse with the same meshes on opposite sides to form the zigzag-shaped sutural vein between and paralleling the secondary veins; fimbrial veins occur along the inside edge of the foliar margin. Epidermal cells have sinuous anticlinal walls with thin cuticle; paracytic stomatal apparatus is irregularly oriented. Diameter of subsidiary cells varies from 50 to 70 /xm. There are uni- and multiseriate trichomes on abaxial surface of leaf.

Geologic and geographic occurrence: Longtan, Wangjiazhai, and Xuanwei

Formations, Upper Permian, western Guizhou Province; Upper Rejuechaka

Formation, Upper Permian and possibly the lowermost Triassic, Shuanghu district of Northern Tibet.

Genus Gigantopteris (Schenk) Gu et Zhi, emend., 1974

Gigantopteris dictyophylloides Gu et Zhi, 1974

G. dictyophylloides appears to be a problematic taxon. It was operationally defined by its isometric compound meshes and the simple dentate margin, but its leaf outline and major vein pattern have been unknown. Considering the present materials and previous studies, two types of gigantopterids can be identified to this species based on venation. One seems to have pinnate secondaries on a single primary vein or midrib, another is in trinerved actinodromous pattern (Fig. 60). This species obviously needs to be emended. The first type should be reserved to G.

53 dictyophylloides, while the second type deserves a new genus or higher category.

However, an entire leaf of the first type has not been found to be used as the

lecotype to emend G. dictyophylloides. There is also no well-preserved compressed

or impressed material to be used to establish the second type as a new taxon.

Similarly, although the anatomy of the present permineralized foliar pieces

showing the venation type of G. dictyophylloides, it is unknown whether the lamina

belongs to the pinnate or actinodromous types. Anatomy of the present specimens

is generally similar to that of G. dictyophylloides described by Guo et al. (1993),

except for a few differences. According to Guo et al. (1993), the tracheids are also

5-50 fim in diameter, and with annular and helical thickenings and scalariform pits,

circular to oval and polygonal bordered pits. However, the epidermal cells are

described with sinuous anticlinal walls instead of straight anticlinal; and the stomata

are limited on the abaxial epidermis only and measured up to 70-100 fim in

diameter, about double sized as the present stomata. It is uncertain whether those stomata were inaccurately measured or really larger. The different stomatal type might correspond to the different leaf types, although their correlation is unknown.

Considering these uncertain aspects, the best way to handle the present materials, at the present time, seems to retain them in G. dictyophylloides in the original definition of Gu and Zhi (1974).

54 DISCUSSION

Ecological Habit -- The leaves of Gigantonoclea guizhouensis are large (often

more than 8,000 mm^) and characterized by a thin lamina (about 110-140 jim thick)

with very thin cuticle and poorly differentiated mesophyll. Some ovate G.

dictyophylloides leaves found at the Yueliangtian Mine are up to 50 cm long and

about 40 cm wide. These large leaves in conjunction with a thin lamina and cuticle,

suggests that they were living in an area of high humidity and tropical climate. A

tropical position for the South China Block during the Permian is supported by

paleomagnetic studies (Lin et al., 1985; Scotese and Barrett, 1990; Scotese and

McKerrow, 1990).

In Gigantonoclea guizhouensis, stomata suggest high humidity. The stomata

are not recessed and guard cells with radially thickened walls occur next to the

stomatal pore. Such thickenings make the pores difficult to close completely (Aylor

et al., 1973). This stomatal mechanism would thus suggest a high incidence of water

loss, if the environment was not humid. In other words, it might be so moist that

almost all stomata were preserved in the pore-open state, although it is unknown

whether this was caused by an inability to close completely or by preservation. The

short, large-diameter tracheid at the end of a veinlet might also indicate the presence

of some guttation mechanism, although there is no evidence of an epithem or a

specialized pore in the epidermis overlying these tracheids. All of the above

characteristics are typical of understory plants growing in weak light, high temperature, and high atmospheric and soil moisture conditions. This environment

55 would be consistent with the paleomagnetic reconstruction of South China Block at this time.

The spines on the abaxial surface of the midrib of G. guizhouensis resemble the spines and prickles of many modern plants (e.g., Rosa, Robinia pseudoacacia, and

Zanthoxylum) in their pointed tips and superficial origin. The spines on the midrib of G. guizhouensis may have functioned in attachment, suggesting a climber or liana habit. Compared to the large size of the leaves, the gigantopterid axis is relatively slender, a feature which also suggests an understory plant with a liana habit. Yao

(1983a) described hook-like structures that were modified from the secondary veins of Gigantonoclea fukienensis and Gigantopteris cordata, and Halle (1927, 1929) originally proposed that the leaves of G. hallei and G. lagrelii were modified into hooks for climbing. Yang (1987) described and illustrated some spines modified from a normal leaf on the node of G. rotundifolia. In the present materials, the hook-like structures have also been found associated with gigantopterid leaves

(Chapter V). Thus, perhaps many of the gigantopterids were lianas with different structural modifications.

In the case of G. dictyophylloides, the lower order veins have hypodermal sclerenchyma ribs and this suggests that such a larger leaf might also need additional support from the sclerenchyma ribs. Considering that the associated stems are narrow and long, this species might also be a liana.

Comparison among gigantopterids - Morphologically, both Gigantonoclea and

Gigantopteris belong to the G-Type gigantopterids. Both are distinguishable mainly

56 based on their simple or compound mesh venation. Anatomically, both G. guizhouensis and G. dictyophylloides share many anatomic features, such as the same hypodermal sclerenchyma ribs, endodermis enclosing the vascular tissue, tracheids with various secondary wall thickening patterns, and paracytic stomata on the abaxial surface. These features suggest all Asian G-Type gigantopterids might be closely related.

However, G-types seem unrelated to C-types. Both types are morphologically very different (Chapter III). Anatomy of C-type gigantopterids have not been known, except for epidermis and stomata (Yao and Crane, 1986; Yao and Wang,

1991). Each stoma consists of two guard cells and about six subsidiary cells with 2-6 papillae overarched the pore. Yao and Wang (1991) compared stomata of

Gigantopteridium sp. with thatofAipteris nerviconjluens (Huang, Z. and Zhou, 1980).

These stomata are also comparable with those of the seed fern Callipteris conferta

(Barthel and Haubold, 1980). C-type Cathaysiopteris has been considered to have originated from Callipteris tachingshanense based on the same leaf architecture

(Chapter III). Now, the same stomatal type provides a strong support to the hypothesis. Therefore, the C-type Gigantopteridium might have affinities with

Aipteris, Aipteridium, and Callipteris, and thus they possibly belong to seed ferns also.

The solid heart-shaped xylem of the secondaries in the present G. dictyophylloides appears to be similar to those U- or V-shaped xylem in the midrib or secondaries of G. guizhouensis. Both also have endodermis enclosing vascular tissues. However, the midrib of the Texan Delnortea has the relatively developed

57 secondary xylem surrounding a parenchymatous central area, and has no endodermis

(Mamay et al., 1988). This American gigantopterid is thus anatomically different from Asian G-types, and they may be unrelated. However, the relationships between

Asian G-types and other American gigantopterids, especially Gigantonoclea sp., remain unknown.

Comparison with other groups -- Morphologically, gigantopterids have been considered similar to angiosperm leaves, since their broad leaves have mesh venation, especially the compound anastomosing venation of Gigantopteris. However, similar venation has also been found in a few ferns, seed ferns, and modern Gnetum. For example, some polypodiaceous ferns have simple anastomosing veins and some have a series of compound meshes that enclose freely ending veinlets, with or without expanded endings (Tryon and Tryon, 1982; Hennipman and Hetterscheid, 1984;

Hetterscheid and Hennipman, 1984). It is hard to distinguish the venation of the G- type gigantopterids from those ferns. Gnetum, or angiosperms, based only on the multi-order vein nets.

Both G. guizhouensis and G. dictyophylloides have similar paracytic stomata, although the former has both straight and undulated anticlinal cells rather than just the straight type as found in the latter. Paracytic stomata are widely distributed in the plant kingdom, with the earliest known from the Early Devonian lycopod

Drepanophycus spinaeformis (Banks, 1976). They are also known from ferns (Type

X of Thurston, 1969), seed ferns, angiosperms, and possibly bennettitaleans

("mesogenous-tetralabrate" stomata of Krassilov, 1976). However, G. giiizhouensis

58 differs from other groups in the occurrence of polar cells, leaf venation, and other

characteristics. Both gigantopterid taxa appear to be more derived than ferns in

their large compound or simple broad leaf and the highly differentiated tracheary

elements. The spines found in G. guizhouensis have not been found in any ferns.

Some features of these gigantopterids can be compared with those of seed

ferns. The stomata in G. gdzhouensis look similar to those of the Carboniferous

seed fern Alethopteris sullivantii (Stidd and Stidd, 1976; Reihman and Schabilion,

1985; Stidd, 1988), which exhibits guard cells enclosed by subsidiary cells and similar

radial thickenings on the guard cells. However, no polar cells have been found in

A . sullivantii. The oval water storage cell connected with the ending veinlet in G. giizhouensis seems to be comparable to inflated vein tips of Feraxotheca culcitaus

(Taylor and Millay, 1981), but more developed than the latter. The seed fern

Schopfiastnim decussatum from the Middle Pennsylvanian of the Illinois Basin also

exhibits some anatomical similarities to G. guizhouensis. These include secretory

cavities in the lamina, the presence of a few paracytic stomata, and U- or V-shaped xylem forms in the pinna midrib (Stidd and Phillips, 1973). However, most stomata

in this taxon are anomocytic, and xylem shapes in the thicker pinnae are generally

Y-shaped, arguing against any close relationship with G. gdzhouensis. Although it

has been suggested that the present G-type gigantopterids originated from

Cathaysian seed fern E. triangdaris (Halle, 1927; Asama, 1959; Yang, 1987), this hypothesis has not been anatomically tested yet, since no anatomical data have been

reported from the latter.

59 American gigantopterid Delnortea has been compared with extant Gnetum

(Mamay et al., 1989), but it is difficult to compare G. guizhouensis and G. dictyophylloides with Gnetum. The only similarities appear to be the presence of

mesh venation and gymnospermous vascular tissue in the petiole. They differ in that

the vascular tissue in the lower vein orders of these Asian gigantopterids is U- or V-

shaped or heart-shaped and enclosed by endodermis, while Gnetum petioles contain

a shallow arc of five to seven vascular bundles which are not enclosed by a special

sheath (Rodin, 1967). In Gnetum ula, stomata may be variable, including

anomocytic, paracytic with a single subsidiary cell, and cyclocytic types (Inamdar and

Bhatt, 1972). In gigantopterids most stomata are of the paracytic type. The compound reticulate venation in Gnetum is more complicated than that of G. giiizhouensis, but similar to that of Gigantopteris species. G. nicotianaefolia resembles

Gnetum not only in the compound mesh venation, but also in the elliptic to long elliptic leaf shape, undulated to smoothly entire leaf margin, and the pinnate secondaries on the single primary, although these features are similar to some angiosperms too (Figs. 33-35).

The actinodromous type gigantopterids seem to be the most derived. In extant plants, this type has only been characterized in angiosperms. Further comparative study between the reproductive organs of gigantopterids and angiosperms is needed to test whether they have real affinity or just morphologically resemble each other (parallelism).

60 In conclusion, both G.giiizhouensis and G. dictyophylloides may be interpreted as liana plants growing in a tropical forest. All characteristics known to date suggest that these G-type gigantopterids are systematically different from both the Asian

Gigantopteridium and North American Delnortea. Gigantopteridium seems to be related to callipteroid seed ferns, while Delnortea has been compared with Gnetum

(Mamay et al, 1988). Although G-type gigantopterids are similar to some

Carboniferous seed ferns, but stomatal types and xylem configurations differ. The compound mesh gigantopterids diverge into two groups, one has the pinnate secondary venation and the other is in the actinodromous leaf pattern. Both groups have leaves similar to those of anthophytes (gnetophytes and angiosperms).

61 CHAPTER V

MORPHOLOGY AND ANATOMY OF GIGANTOPTERID AXES

ABSTRACT

Many slender axes, Rhizomopsis gemmifera, with spine-like dots and/or vertical ribs, have been found from the Upper Permian, western Guizhou Province, China.

In this chapter, they are categorized into two types. One type, Spinivinea yunguiensis gen. et sp. nov., bears spine-like dots and vertical ribs and has been verified related to Gigantonoclea based on the organic connection and the identical anatomy.

Another type, Vasovinea tianii gen. et sp. nov., also has vertical ribs, but it exhibits hook-like or tendril-like structures outside and vessels in xylem. This type is suggested to belong to Gigantopteris based on anatomical similarities, although no organic connection has been found. These slender gigantopterid stems suggest they lianas and occurred in the Permian tropical rain forest. Systematically, the presence of eustelic stems suggests that gigantopterids are seed plants. Vasovinea has vessels in secondary xylem similar to those of gnetophytes but without tori in bordered pits, while the vessels in metaxylem with scalariform perforation plate which resembles that of primitive angiosperms. This suggests that some gigantopterids with some features developed into the anthophyte level.

62 INTRODUCTION

Although gigantopterids have been studied since Schenk (1883), most reports

have involved only leaves. Gigantopterid leaves have often been found associated with some axes of Rhizomopsis gemmifera, but no axes have been confirmed as of

gigantopterids. R. gemmifera was established by Gothan and Sze (1933) for some

spiny axes which were reportedly similar to a rhizome with bud-like structures, spine­

like dots, vertical ribs, and sometimes with a bunch of fine stick-like structures on a

protuberance. The taxon was named for the rhizome-like axis bearing bud-like

structures. Gu and Zhi (1974) published additional specimens of R. gemmifera

showing the spine-like dots too. However, the bud-like structure was not mentioned

or shown in their material. Following this example, more Permian spiny axes were

identified to this species (Zhao et al., 1980; Li, X. et al., 1982a, 1982b; Yao, 1983a),

although none of them have bud-like structures.

Gothan and Sze (1933) suggested Rhizomopsis gemmifera as the possible rhizomes of the associated gigantopterids, since some bud-like structures were found both on some axes and gigantopterid leaf bases, but this was not well demonstrated in their paper. Gu and Zhi (1974) guessed that these spiny axes might be the

rhizomes of Gigantonoclea acuminatiloba based on the association only. Although they stated that R. gemmifera was also found from Guizhou, none of their demonstrated specimens of R. gemmifera were collected from Guizhou. Also, no specimens of G. acuminatiloba have been reported from Guizhou. It seems impossible for R. gemmifera from Guizhou to be related with G. acuminatiloba. Li,

63 X. et al. (1982a) considered that R. gemmifera from Tibet might be the axes of the associated Gigantonoclea leaves, while Yao (1983a) presented this type of axis associated with G. nicotianaefolia. Therefore, the real relationship between R. gemmifera and gigantopterids has not been verified.

Many axes of Rhizomopsis gemmifera have been found associated with gigantopterids {Gigantonoclea and Gigantopteris) from the Upper Permian, western

Guizhou Province, China. The term ’axes’ has been used here because it is sometimes difficult to determine whether these axes represent stems, petioles, or rachides. These axes are preserved as impressions, compressions, and permineralizations. Considering their morphology and anatomy, these axes are placed into two new genera, Spinivinea and Vasovinea, both have been reconstructed with some Gigantonoclea and Gigantopteris leaves respectively. On the basis of these reconstructions, their ecological habits and their systematic affinities are also discussed.

SYSTEMATICS AND DESCRIPTION

Order - Gigantopteridales Li et Yao

Family - Gigantopteridaceae Koidzumi.

Spinivinea gen. nov.

Generic diagnosis -- Axis slender, 1-5 cm in diameter, with dense, firm spines from 0.5 to 2 mm long and arching downward; sclerenchyma cells found directly beneath hypodermis aggregated into vertical strands and internally embedded in

64 cortical parenchyma cells; endodermis enclosing eustelic vascular cylinder; xylem consisting of a ring of collateral vascular segments, each consisting of a mesarch axial strand (primary xylem) and more or less secondary xylem with uniseriate rays.

Etymology: The generic name is composed of spin- ([L] = spine) and vinea

([L] = vine) for the liana axis with spines.

Type species: Spinivinea yungiiiensis gen. et sp. nov.

T^pe locality: Yueliangtian Coal Mine, Panxian, Guizhou, China.

Stratigraphie occurrence: Lower and Upper Xuanwei Formations, Upper

Permian.

Age: Longtanian and Changxingian, Late Permian.

Spinivinea yunguiensis gen. et sp. nov.

Specific diagnosis - Axis slender, mostly 1-2 cm in diameter, with dense and firm spines, from 0.5 to 2 mm long, straight or arching downward; sclerenchyma cells directly beneath hypodermis, aggregated into vertical strands, internally embedded in vertically linked cortical parenchyma cells; endodermis occurring between cortex and vascular cylinder and consisting of large cells with internal tangential walls much thicker than external tangential walls; vascular cylinder eustelic, consisting of a ring of xylem segments; each xylem segment containing a round to triangular shaped axial strand to the inside and a secondary xylem portion toward the outside; each mesarch axial strand with 1-3 protoxylem columns; secondary xylem segments in different axes varying from very narrow to relatively wide (up to 15 cells), and from isolated to

65 tangentially connected with each other; no growth ring in secondary xylem; from primary to secondary xylem, tracheary cells exhibiting annular, helical, or scalariform thickenings and multiseriate long to short transversely elongated bordered pits; rays occurring every 1-3 tracheid rows, mostly 5-30 (up to 70) cells high and uniseriate, but a few rays with a central fusiform-shaped part up to 4 cells wide.

Holotype: Specimen PLY02. Slides #C10-4S1, #C10-4S2, #C10(L)-1,

#C10(L)-2. Figs. 110-118 in this dissertation.

Paratypes: Specimen PLY02. Slides #A, #A1-1-2-2, #Al-2-l-2, #A2-2-2-

1, #A2-P1-1, #C7-6T, #C10(L)-2, #C15-(R-A). Figs. 119-127 in this dissertation.

Etymology: The specific name is given after the Yun-Gui Plateau.

Description - Axes are slender, mostly 1-2 cm in diameter (Figs. 110, 119,

126-127). These axes bear spines which are mostly 0.5-2 mm long, and about 1 mm in diameter at bases. These spines are composed of small cells with thick cell walls.

Spine bases are separated from the axial cortex by several layers of small cells, and have no connection with vascular tissue (Figs. Ill, 119,126,127). Thus, these spines possibly be superficially originated. They are identical with those found on the midrib of G. guizhouensis (Li, H. and Tian, 1990; Li, H. et al., 1994c). Since the spines on the leaf are arching downward, the present axial spines may arch downward also or extend out straight.

Besides spines, cortical part consists of epidermis, hypodermis, cortical parenchyma, and sclerenchyma strands. Most epidermal cells are vertically elongated

(40-75 jLim) and rounded squared (20 x 20 fim) in transection. The hypodermis

66 consists of 3-5 layers of collenchyma cells which are 20-200 /xm long and 20-35 fim in diameter. Directly beneath the hypodermis, there are some sclerenchyma strands which consist of fibrous cells, 15-25 /im in diameter and 200-1000 /xm long. Mostly, these strands are internally surrounded by cortical parenchyma cells which are mostly about 70 /Ltm in diameter and arranged into vertical rows. Occasionally, some huge oval structure (550 x 950 /xm), similar to an essential oil cavity, is present in the outer cortex (Fig. 120). The inner cortical part is very wide (Figs. 129-130) and often broken so that a big space is usually present between the outer cortical part and vascular tissue (Figs. 110, 119-120, 126-127).

The vascular cylinder is relatively small and surrounded by 1-2 layers of endodermal cells which are elliptic (65-90 x 90-125 /xm) on transection and more or less long square shaped (65-85 x 75-110 /xm) on longitudinal section. The endodermal cells have their inner tangential walls thicker than outer tangential walls

(Figs. 121, 122 arrows). In the stems with developed secondary xylem, endodermis was rarely preserved (Fig. 110,126-127), and this might be caused by the collapse of the parenchyma tissue. Vascular cylinder consists of many xylem segments (6 in Fig.

110 and 14 in Fig. 119), each has a round to triangular shaped mesarchy axial strand on the pith side and more or less developed secondary xylem outside. Each primary xylic bundle has one (Figs. 112, 121) to three protoxylem centers. Centrifugal metaxylem is narrower than the centripetal metaxylem. From the protoxylem to the metaxylem, tracheids vary from 10-70 /xm in diameter, and 1,500-3,000 /xm in length.

Secondary walls have annular, helical or scalariform thickenings (left sides on Figs.

67 113 and 123; Fig 124), uniseriate transversely elongated pits, or multiseriate transversely elongated bordered pits (Figs. 114, 125).

Secondary xylem varies tangentially from the same width as the axial strand

(primary xylem; Fig. 119) to be expanded (Fig. 121), radially from less than four cells wide (Figs. 119-121) up to about 15 cells wide (Figs. 126-127, 129-130). In the former cases, the vascular bundles are mostly composed of primaiy xylem, and isolated from each others; while in the latter cases, secondary xylem segments are tangentially connected each other to form some large woody segments. Secondary tracheids vary from mostly about 20 x 30 /xm (Fig. 121) to about 60 x 95 /xm in cross sections (Figs. 112, 128, 130) and 1,700 - 3,500 /xm in length. The side walls of secondary tracheary elements have multiseriate (up to nine rows), alternatively arranged bordered pits which are more or less transversely elongated (mostly 10 x

12/xm; Figs. 113-114, 116-117, 131). Xylic rays occur every 1-3 rows of tracheids, and are mostly one cell wide (Fig. 131), except some rays with fusiform-shaped central parts which can be up to four cells wide. Many rays are about 5-30 cells high, but a few can reach about 70 cells high. On transection, each ray cell is about

20-25 /xm wide tangentially and about 50 /xm long radially. The heights of ray cells vary from 30-50, even up to 70 /xm. Each cross-field contains 1-3 rows of oblique pits (4x9 /xm; Figs. 117-118).

Vasovinea gen. nov.

Generic diagnosis — Stems slender, about 1 cm in diameter, with hook-like or tendril-like structures, and sometimes with a few spine-like appendages; vertical

68 sclerenchyma strands beneath the hypodermis and internally surrounded by cortical parenchyma cells; endodermis at the innermost cortex; eustelic vascular cylinder splitting into several segments, each consisting of both a mesarchy axial strand inside and secondary xylem outside; lateral walls of protoxylem tracheids, metaxylem tracheary elements, and secondary xylem elements with helical thickenings, mono- to multiseriate scalariform bordered pits, and multiseriate bordered pits (without tori) respectively; centrifugal metaxylem having vessels with scalariform perforation plate on highly inclined end walls; secondary xylem having large vessels, with foraminate-like perforation plates, at the inside and typical tracheids on the outside; rays mostly uniseriate and occurring every one to three rows of tracheids.

Type locality: Yueliangtian Coal Mine, Panxian, Guizhou, China.

Type species: Vasovinea tianii gen. et sp. nov.

Etymology: The generic name is based of vaso- ([L] = vessel) and vinea ([L]

= vine) for the axis with vessels.

Stratigraphie occurrence: Lower and Upper Xuanwei Formations, Upper

Permian.

Age: Longtanian and Changxingian, Late Permian.

Vasovinea tianii gen. et sp. nov.

Specific diagnosis - Stem about 1 cm in diameter consisting of epidermis, 2-4 layers of hypodermal cells, and sclerenchyma strands embedded in the cortical parenchyma cells; stem bearing with hook-like or tendril-like structures, and

69 sometimes with spine-like appendages; eustelic vascular cylinder splitting into 5-9 woody segments, each with a mesarchy axial strand (primary xylem) inside and secondary xylem outside; helical or branching helical thickenings, and mono- to multiseriate scalariform bordered pits occurring on lateral walls of protoxylem tracheids and metaxylem tracheary elements respectively; vessels in centrifugal metaxylem with scalariform perforation plate on highly inclined end walls; secondary xylem consisting of two radial portions; the inner portion containing 1-5 large vessels, and the vessels decreasing in diameter outward, while the outer portion consisting of regularly arranged tracheary elements; most vessel members joining each other by foraminate-like perforation plates. Le., the long sloping end walls perforated with multiseriate circular pores; a few vessel members with almost horizontal perforation plate on the end walls; the lateral walls of tracheary element in secondary xylem exhibiting multiseriate circular bordered pits, but the primaiy cell walls of the pits without tori; homocellular rays, 1-2 cells wide, occurring every 1-3 tracheary cells.

Holotype: Specimen L9407, slide #C-B16, #D-T2. Figs. 132-133, 135, 138 in this dissertation.

Paratypes: Specimen PLY03 (slides #1, #6, #7, #11, #34), PLY04 (slides

#B , #6), PLY02 (slides #C10(1-1), #E-1). Figs. 134, 136-137, 139-148 in this dissertation.

Etymology: The specific name is proposed in honor of Professor Baolin Tian, the Beijing Graduate School, China University of Mining and Technology, for his contributions to my previous studies on gigantopterids.

70 Description: One stem is only 4 x 6 mm in cross section (Figs. 132-133, 135,

138), with branching hook-like structures (Fig. 135). The shape and size of this hook-like structure is similar to that of compression hook-like structure (Fig. 108).

The vascular tissue can be found in the basal part of the hook-like structure, but it gradually reduces distally. Another stem is calculated about 10 mm in diameter. It bears some elongated and curved tendril-like structures which are, 300-500 /im in diameter, in wart-like forms protruding from the epidermis or circular forms embedded in the surrounding sediments (Fig. 134). These tendril-like structures may have preserved with nothing inside (arrow in Fig. 137) or with many small cells and a thin hollow center (Fig. 109). Sometimes, spine-like structures can be rarely found on stems (Fig. 133 right side).

The cortical part, similar to that of 5. yunguiensis, also consists of epidermis, hypodermis (2-4 cells thick), sclerenchymatous strands in the outer part of cortex, and a wide inner cortical portion of parenchymatous cells (Figs. 132, 134). The cortical parenchyma cells were often broken greatly. Endodermis is poorly preserved as a darker cell layer at the innermost of the cortex (Figs. 132 and 133, lower).

The eustelic vascular cylinder consists of about 5-9 woody segments in different sizes. Each segment appears fan-shaped in cross section, and contains both primary and secondary xylem. In Fig. 133, two branch traces, each about 750 fim in diameter, are given off between the main axial segments and covered by endodermis outside. The branch traces show a small pith surrounded by mesarch primary xylem and secondary xylem. At the center of the stem is the pith with broken parenchyma

71 cells (Figs. 132-133). The pith is surrounded by mesarch axial strands (primary xylem; arrow head in Fig. 133). The protoxylem tracheids can be narrower than 20

/xm in diameter with helical or branching helical thickenings (Fig. 139, left).

Centripetal metaxylem has fewer (mostly only one cell wide) and smaller tracheids

(less than 50 jxm in diameter). Centrifugal metaxylem 1-3 cells wide, and the tracheary elements are larger (up to 100/xm in diameter), with uniseriate scalariform pits (Fig. 139, right upper part) or 2-3 rows of scalariform pits (Fig. 139 arrowhead).

Some vessel elements occurred in metaxylem are characterized by multiseriate scalariform perforation plate on their highly inclined end walls (Fig. 140).

The secondary xylem has tracheary elements arranged into radial rows, each with an inner portion of large vessels (1-5 vessels wide) and an outer part of tracheids. When the inner portion is only 1-2 vessels wide, the vessels can be up to

500 /xm in diameter (Figs. 146-147). When it is about 3-5 vessels wide, the vessels are narrower and they decrease in diameters from 250 to 150 /xm or smaller outward

(Figs. 132-134). Vessel members are about 4,500-5,000/xm long, joined by their end walls. These end walls vary from long sloping form (up to 1,200 /xm long; Fig. 144) to almost perpendicular to the side walls (in the left lower vessel of Fig. 145). They appear with foraminate-like perforation plate, i.e., their end walls are perforated with multiseriate (up to 13) rows of circular pores. The larger pores (14-16 /xm in diameter) in the central area (Figs 142, 148) are completely developed, and the peripheral, smaller ones (about 10 /xm only) often exhibit incompletely dissolved primary cell wall material (Figs. 143,148 arrowhead). Thus, the perforation appears

72 to be a result of the dissolution of the primary cell wall of paired bordered pits.

The remained primary cell wall is flat without any trace of torus. The lateral walls of both vessel elements (Fig. 142, lower right) and tracheids (Fig. 141) have developed with only multiseriate circular bordered pits which are less than 10 /xm in diameters, and no tori have been found on the primary walls inside pits.

The outer zone of tracheids is about 4-7 cells wide and the cells are mostly about 40-50 /xm in diameter. The cells may be rectangular (Figs. 132-133) or triangular shaped (Figs. 146-147). Similar to vessel members, their side walls have bordered pits also, but their end walls were not perforated. Every 1-3 radial rows of tracheids are separated by parenchymatous rays which are mostly homoseriate, 1-2 cells wide (Figs. 132-134, 146-147) and as tall as 60 cells. Rays consist of homocellular parenchyma cells, mostly 25-50 /xm high, and each cross-field has 3-9 or more oblique pits (Fig. 143 left).

One stem has been found closely associated with a leaf of Gigantopteris meganetes (Figs. 58, 136-137). Another stem (Fig. 134) is found on a specimen that has a leaf of G. dictyophylloides (Fig. 60) on the reversal side.

Discussion - Several specimens have 3-5 vessels on each radial row, and the vessels are smaller, mostly 250 to 150 /xm or less in diameter (Figs. 132-134).

However, the specimen showed in 146-148 has only 1-2 vessels on each radial tracheary row, and the vessels are very large (up to 500 /xm in diameter). The latter specimen may represent a different species, but there is not sufficient material to establish a separate species.

73 RECONSTRUCTION

As noted in the introduction, many axes oi Rhizomopsis gemmifera have been

found associated with both Gigantonoclea and Gigantopteris leaves. Two types of R. gemmifera are present in the compression and impression material. One type has

spines and vertical striations (Figs. 102-103, 105). This type has been found often

associated with some Gigantonoclea sp. leaves (Fig. 106), or organically connected

with G. guizhouensis leaves (Figs. 53-55). The spines have been anatomically verified

on the midrib of the permineralized G. ff.iizhouensis leaves (Li, H. and Tian, 1990;

Li, H. et al., 1994c). They are found on the cortical part that contains epidermis,

hypodermis, sclerenchyma strands in the outer part of cortex, and a wide inner

cortical portion. It is these sclerenchyma strands that give the external appearance

of vertical ribs or striations in the impression and compression specimens.

This typical cortex with spines is identical with that of S. yungiiiensis axes.

Some separately preserved cortex of this type (Fig. 107) might be detached from S. yunguiensis. In addition to the spines and the cortical ribs, both G. guizhouensis and

S. yunguiensis have the same type of endodermis and bordered pits on metaxylem

tracheids. Thus, the stems of G.guizhouensis are suggested to be in the form of the

spiny R. gemmifera in impressions and compressions or in the form of S. yungpiensis

in permineralizations (Fig. 198). However, this does not mean all spiny/?, gemmifera

axes and S. yunguiensis stems belonging to G. guizhouensis. They may be related with

other Gigantonoclea species too. Also, the possibility that these spiny axes to be

related with some Gigantopteris species or other taxa can not be excluded before all

74 these taxa have been anatomically examined. Therefore, they are not placed into

one taxon.

Another impressed and compressed type of Rhizomopsis gemmifera axes also

has vertical ribs, but without or with rare spine-like dots. This type has been found

associated with Gigantopteris leaves (Figs. 104,149 top). In permineralized material,

the secondary veins of G. dictyophylloides leaves have been found with the cortical

parts similar to that of G. guizhouensis, but without spines. Thus, this type of cortex, with sclerenchyma strands in the outer cortical part, has been found in both

Gigantonoclea and Gigantopteris leaves. Among all Permian plants found from western Guizhou, gigantopterid leaves have been found to be preserved solely.

Sometimes a few Fascipteris, Pecopteris (Figs. 191-197), and Plagiozamites leaves are also mixed together. However, no midribs, rachides, or stems of these taxa have been found with the cortex containing sclerenchyma strands. Thus, gigantopterids of Guizhou are uniquely characterized by this type of cortex.

This typical cortex with rare spine-like structures has been found in Vasovinea tianii, which is often associated with Gigantopteris leaves. Since this type of cortex is characteristic of gigantopterids, V. tianii can also be suggested as belonging to the gigantopterids. It may be related to Gigantopteris leaves, because both have a cortex with sclerenchyma strands, but without or with the rare spine-like structures. Thus, the second impression and compression type of Rhizomopsis gemmifera axis may also represent the same kind of Gigantopteris plant. This assumed reconstruction of

Gigantopteris leaf and V. tianii, as well as the second type of R. gemmifera, needs to

75 be verified in future studies. In short, Gigantonoclea guizhouensis leaves should be

reconstructed with the spiny axes of Rhizomopsis and Spinivinea (Fig. 198).

Vasovinea stems bearing vertical ribs, rare spines, and hooks may be related to

Gigantopteris leaves (Fig. 199).

ECOLOGY

Halle (1929) reported some hook-bearing gigantopterids from central Shansi

(= Shanxi) and suggested that the gigantopterids grew as lianas in a tropical climate.

Yao (1983b) reported more hook-like structures and again considered gigantopterids lianas growing in a low-land tropical forest. The present material supports these suggestions with some new ecophysiological interpretations.

Ecology of Spinivinea - The spiny axes of Spinivinea found in western Guizhou are slender, mostly less than one centimeter in diameter. Some of the specimens observed in the field are straight and longer than one meter without changing diameter. If they were not hanging on other plants, such slender stems would be bent downwards by their large and heavy Gigantonoclea leaves. Therefore, they must be lianas in nature, similar to lianas with spines or thorns found in present day tropical rain forests (Walter, 1983). It is the numerous spines on stems and leaf major veins that provided mechanical attachment so that the axes could hang on other trees, bear heavy leaves, and keep the straight. The axes are generally without leaves, although they and the leaves are intimately associated together. The leaves might, like those of modern lianas, have dropped as the hanging axes age.

76 Anatomically, the small amount of xylem in the stem of Spinivinea also

suggests a liana habit. Some axes, which contain very little secondary xylem (Figs.

119-120), may be younger or, possibly, herbaceous in nature. Other Spinivinea axes

have relatively well-developed secondary xylem (Figs. 110-111, 126-130), and may

represent older stages of woody lianas. The endodermis in both axes and major

veins apparently played an important role in maintaining a higher water potential

inside the steles. With the assistance of the endodermis, tracheids could conduct

sufficient water to the high leaves, even though the number of tracheids in some axes

is very small.

However, tracheids usually conduct water at relatively low efficiency so that

Spinivinea might not climb to the canopy top, but some understory layer. In such

layers, light is weaker so that the leaves of Gigantonoclea guizhouensis are thin and

the mesophyll did not differentiate into palisade and spongy tissues (Chapter IV).

Also, the humidity there is relatively high so that the stomata of G. guizhouensis are flat. Moreover, the leaves may have required relatively less water from the stems because of the low rate of evapo-transpiration. Therefore, the stems can conduct

enough water although they are very thin and contain few tracheids.

Another reason for the slender axes to be compatible to the liana habit may be the simple mesh venation type of 0 . guizhouensis. All Gigantonoclea species are characterized by fewer vein orders, and the veins diverge at narrower angles, than those of Gigantopteris. This will decrease the resistance to water conduction distally, since the Leaf-Specific Conductivity of a modern liana decreases at branch junctions

77 (Ewers et al., 1989). In these ways, the leaves and stems are mutually compatible to the liana habit.

Ecology of Vasovinea — Stems of Vasovinea usually bear very few spines, but they have tendril-like and/or hook-like structures. The latter are much bigger and stronger than spines of Spinivinea, and could help Vasovinea stems hang on trees more steadily. Vasovinea stems are also very thin, and, thus, also suggest a liana habit.

Anatomically, the stems have sclerenchyma strands beneath the hypodermis.

However, no endodermis has been found in the stem, although it has been found poorly preserved in a secondary vein of a Gigantopteris leaf (Fig. 101). Importantly, large vessels occurred in the xylem, which are much more efficient in water conduction than tracheids. The vessels found in Vasovinea are significant in interpreting the plant habit. This cell type may be highly variable in diameter, length, end wall orientation, and the type of perforation plate (Carlquist, 1988a).

Wood characteristics, including vessel diameter, have been correlated to habitat, with narrower vessels typically found in more arid sites (Carlquist, 1975). Vessel diameter can also be correlated to habit, as lianas typically have larger vessel diameter

(average 157 /xm; up to 558 /xm diameter) than woody trees in both Gnetum and dicots (Carlquist, 1975; Ewers, 1985; Ewers and Fisher, 1989; Ewers et al., 1990;

Fisher and Ewers, 1995). Modern lianas typically possess a large ratio between large leaves and narrow stems, and have the largest mean vessel diameter for any category based on habit or habitat (Carlquist, 1975, 1991). Large vessels in liana stems

78 probably represent an adaptation to more efficient water conduction, especially where evapo-transpiration is high in sunny canopy tops. In addition, since these

plants are not self-supporting, their xylem tissue can be used principally for water

conduction instead of compromising between support and conduction as in other woody plants. These same anatomical characteristics that are typical of a liana habit

(narrow stems, large vessel diameters, massive leaves) also appear in Vasovinea stems

and probably represent similar physiological adaptations. The vessels of V. tianii are

150-500 /rm in diameter and comparable with extant lianas. Thus, V. tianii can be

suggested to be liana plants also. As the vessels increase in diameter, they would be more vulnerable to cavitation so that the vascular tissues are fragile. The relatively thick zone of sclerenchymatous strands might supply some mechanical support to the axes. However, the major mechanical support to the axes might come from the hook-like or tendril-like structures. Thus, their presence and the fragmented nature of the vascular tissue provide additional support for the reconstruction of these plants as lianas.

In extant lianas, large cordate leaves are mostly located in sunny canopy environments (Givnish and Vermeij, 1976). The cordate shaped Gigantopteris leaves

(Figs. 38-40, 59, 64, 68, 70) are often larger than 400 cm^ so they might grow in a sunny canopy layer too. 0. dictyophylloides leaves are thicker than those of

Gigantonoclea guizhouensis, and contains 2-3 layers of palisade cells, and sunken stomata on the abaxial side as well. These features also suggest the leaf was exposed in a sunny area. Such a large leaf exposed to sunshine would evaporate great

79 amounts of water, and require an efficient water conducting tissue. With such water

requirements, it is not surprising that vessels evolved in these Permian plant axes.

The complex mesh venation of Gigantopteris also requires an efficient water

conducting tissue. This venation consists of more vein orders and the veins diverging

at wider angels (Figs. 41,73), than those of Gigantonoclea. These would increase the

resistance to water conduction. In other words, such a leaf with higher water

conductive resistance will demand a stem that transports water more efficiently. The

occurrence of vessels might be such an advantage to meet the requirement without

increasing the stem diameter.

Habitat - These fossil lianas of gigantopterids might have grown in a tropical

rain forest, like most living lianas which are located in tropical rain forests (Walter,

1983; Gentry, 1991). Combining analyses of coal-sediment facies (Tian et al, 1990), floral assemblages, and large leafed gigantopterids, western Guizhou can been suggested in a tropical forest during Late Permian. This conclusion of tropical latitudes of Guizhou during the Permian is also supported by paleomagnetic results

(McElhinny et al, 1981; Lin et al, 1985).

Both Spinivinea and Vasovinea are considered as lianas and both have often been found preserved together. This suggests that they might have grown together in the same habitat. However, the former may have grown in understory layers, while the latter may have climbed up to the canopy top.

80 PHYLOGENY

The systematic attribution of gigantopterids has been variable. Schenk (1883) described G. nicotianaefolia as a fern, while White (1912) and Asama (1959) considered gigantopterids seed ferns, although they did not show convincing evidence of seeds. Li, X. and Yao (1983) reported some seed- and synangium- bearing leaves and concluded that gigantopterids are seed ferns. The systematic attributions of gigantopterids are discussed here based on the present anatomical information.

Systematic position of Spinivinea -- All present gigantopterid stems show a eustelic vascular cylinder that consists of a ring of primary vascular bundles and secondary xylem consisting of tracheary elements with bordered pits, which are more or less transversely elongated. Sometimes, bordered pits occurred on tracheary elements of the metaxylem also. Since eusteles have not been found in true ferns, the present gigantopterids are suggested not to be at the true fern level. In some seed ferns, vascular tissues are still in protostele {e.g., Buteoxylonales and some

Calamopitys species) or mixed protostele {e.g., Heterangium) (Taylor and Taylor,

1993). The occurrence of eustele in S. yungiiiensis suggests that the taxon might have evolved at least to the seed fern level.

Spinivinea stems are similar to both Lyginopteris and Callistophyton, among all seed ferns, in pith, eustele, mesarch axial strands, and secretory cells/cavities and sclerenchyma strands in the outer cortex (Stewart and Rothwell, 1993).

Gigantonoclea guizhouensis is also similar to the small petioles of Lyginopteris in V-

81 or W-shaped vascular traces. However, both Lyginopteris and Callistophyton have sclerenchyma strands in a sparganum type. While S. yunguiensis and G. guizhouensis have vertically parallel sclerenchyma strands, and both are also unique in their endodermis and spines.

Systematic position of Vasovinea - The presence of vessels in Vasovinea is a very important character that not only predates the oldest record of vessels, but, more importantly, provides evidence to trace the origins of vessels. Vessels occur in nearly all extant angiosperms and their presence is considered to be an important synapomorphy for the group (Nixon et al., 1994). Vessels also occur in several vascular cryptogams, such as Selaginella (Duerden, 1934), Equisetum (Bierhorst,

1958), and some filicalean ferns (Jeffrey, 1917; Bliss, 1939; White, 1961), as well as in modern gnetophytes (Carlquist, 1992,1994). Vessels are widely believed to have evolved from tracheids by the dissolution of the primary cell walls of pit pairs.

Therefore, some vessel-less dicotyledon plants have been thought to be primitive angiosperms (Carlquist, 1992), although Young (1981) suggested the absence of vessels in these plants was a secondary loss.

To trace the origins of vessels, Bailey (1944) divided all vessel-bearing plants into two types according to their perforation plates. One is the foraminate type that develops from circular bordered pit pair; this type is present in the Gnetales. The second type is the scalariform perforation plate that comes from transversely elongated pit pairs and is widely found in all other vessel-bearing plants. However, both perforation types were described in extant Gnetim and this implies that both

82 gnetalean and angiosperm vessels are homologous (Muhammad and Sattler, 1982).

For this reason, Gnetales and angiosperms have been placed as sister groups in the anthophyte clade (Nixon et al., 1994). Some other cladistic analyses based on morphology also give more or less similar conclusion (Doyle and Donoghue, 1986,

1993; Loconte and Stevenson, 1990).

Carlquist (1996), however, has examined à number of species of Ephedra and

Gnetum and found that the two types of perforation differ not only in shapes, circular vs. scalariform, but also in whether their primary walls bear tori or not. Tori are commonly found in conifers. Ephedra, and some lianoid Gnetum species

(although not in other Gnetum species), but not in primitive angiosperms (although they are present in some highly derived angiosperms). Therefore, he concludes that gnetalean vessels are similar to conifer tracheids and not to angiosperm vessels

(Carlquist, 1988b; 1994,1996). Fisher and Ewers (1995) also conclude that Gnetum vessels were independently originated and consider the similarity of Gnetum vessels to those of angiosperms a case of convergent evolution.

Bailey (1944) pointed out that the primary xylem tended to be a refuge of primitive features. In other words, the features of the primary xylem may be used to trace the affinity of the plant. Wood anatomy of Vasovinea and other aspects of gigantopterids make it an interesting dilemma to determine the systematic position of the group. First, Vasovinea can be suggested to be related to gnetophytes based on the following considerations:

83 1) The circular bordered pits on the lateral walls of secondary tracheary elements and the foraminate-like perforation plates on the end walls of vessel elements are similar to those of Gnetum. Thus, Vasovinea could be related to the gnetophytes. The absence of tori in Vasovinea seems not to be in favor of this conclusion, based on Carlquist's (1996) new hypothesis. However, the absence of tori may be just caused physiologically. In extant plants, the presence of the torus appears to be an advantage in preventing air leakage into water column systems.

The torus is pushed by water pressure to fit the circular border and block the air bubbles out, thus preventing air embolisms (Carlquist, 1996). Air embolisms occur in extant lianas frequently, and this may be the reason why tori develop in some lianoid Gnetum species, but rarely in other species. Vasovinea exhibit a lianar habit and should have tori. However, it seems the presence of the endodermis may prevent the formation of tori, since the endodermis protects and maintains the whole stele as a water column system. So, it may be unnecessary for tori to develop in each individual tracheary element. From this physiological analysis and the fact that many

Gnetum species do not have tori (Carlquist, 1996), the absence of tori from

Vasovinea can not exclude the potential affinity of this plant to the gnetophytes.

2) Permian gigantopterids found from Texas have also been suggested to be comparable with Gnetum (Mamay et al., 1988), although it is uncertain whether

American gigantopterids are homologous with Asian gigantopterids. 3) Some Asian gigantopterids are morphologically similar to Gnetum leaves,

such as G. nicotianaefolia (Figs. 34, 47, 49, 59) that have leaves with pinnate major

veins and entire margin.

On the other hand, Vasovinea might be not related to the gnetophytes, but

possibly to the angiosperms, based on the following considerations:

1) Despite the above ecophysiological analysis and the fact that some Gnetum

species lack tori, the absence of tori from the circular bordered pits of Vasovinea

suggests that the plant may not be related to Gnetum, based on Carlquist's (1996)

emphasize on the importance of the torus. If the presence of tori is a phylogenetic

feature and if Vasovinea were related with Gnetum, then the lianar Vasovinea should

have tori since modern lianoid Gnetum posses tori. The circular bordered pitting

appears to be polyphyletic in origin (Carlquist, 1996). Vasovinea may be merely

superficially similar to Gnetophytes in having foraminate-like perforation. In other words, the absence of tori would suggest a potential relationship to primitive

angiosperms.

2) This conclusion can also be supported by the presence of scalariform pits

on lateral walls of tracheids (Fig. 139) and scalariform perforation plates of vessels

in the metaxylem of Vasovinea (Fig. 140). Although Muhammad and Sattler (1982)

reported that scalariform perforation plates can be found in Gnetum, Carlquist

(1996) believes the occurrence of scalariform perforation plates are extraordinarily

rare in gnetophytes. Therefore, the presence of scalariform perforation plates on the

end walls, and scalariform pits on the lateral walls of metaxylem elements suggests

85 that Vasovinea might not be related to gnetophytes, but to some primitive angiosperms characterized by scalariform perforation plates. This assumption is also consistent with Bailey’s (1940) refuge hypothesis. Although a few ferns also have vessels with scalariform perforation, they do not have secondary xylem, and can not be comparable with Vasovinea.

3) Vasovinea has been reconstructed with Gigantopteris leaves, possibly including some associated actinodromous leaves. Since actinodromous leaves have not been found in gnetophytes, but only in angiosperms (Chapter III), Vasovinea appears to be more likely related to angiosperms rather than to gnetophytes.

Considering the above analyses, the present Gigantopterids, especially

Vasovinea, appear to be a special plant group resembling both Gnetum and primitive angiosperms. This suggests that gigantopterids may be an ancestral group for both gnetophytes and angiosperms. In other words, the origin of angiosperms would be traced back to this Permian Gigantopteris flora. This possibility can be supported by other data:

1). This floral region is a phytogeographical distribution center of modern dicotyledons, especially those primitive angiosperms, such as families of the

Annonales, Hamamelidales, and vessel-less Winteraceae. This region has been proposed as a birthplace of angiosperms (Takhtajan, 1969).

2). Some chloroplast DNA data and the chemical study of oleananes have placed angiosperm diversification as early as the Permian (Martin et al., 1989;

86 Moldowan et al., 1994). Chronologically, Asian Permian Gigantopteris confirm the above prediction.

However, considering the lack of a convincing angiosperm record during the

Jurassic and Triassic, the present Permian gigantopterids appear too old to be the ancestral group of angiosperms. They may be plants morphologically evolved to the level of anthophytes in an isolated clade. Before the reproductive organs of these gigantopterids have been well documented, it is premature to assign them to any plant group. A more realistic hypothesis is to view the vessels in these Permian plants as demonstrating an example of structure/function relationships that became coupled during the evolution of a liana habit, rather than as evidence of the origin of a particular group of plants.

87 CHAPTER VI

THE ASSOCIATED SEEDS

ABSTRACT

Several Permian seeds, Carpolithus speculatus, are described from western

Guizhou. C. speculatus seeds have been previously reported with unknown affinity, but they are found often associated with gigantopterids in my collections. Three compressed seeds exhibit a short stalk next to either a primary or a secondary vein on the abaxial surface of Gigantopteris leaves. Another compressed seed appears to have a stalk attached to a secondary vein of a gigantopterid leaf. Tliis suggests that

C. speculatus might belong to gigantopterids, although some associated permineralized seeds provide no support to this hypothesis. These seeds are different from other previously reported seed-bearing gigantopterids and also different from those of seed ferns from the same flora or other contemporaneous floras. Two unusual compressed structures have also been found attached to a gigantopterid vein, each consists of a long stalk and a strobiloid part. They may represent another type of reproductive organ from the gigantopterids. Considering previously reported gigantopterid fructifications and the present material, gigantopterids are suggested to be a polyphyletic seed plant group that may include several different lineages.

88 INTRODUCTION

The great attraction of the Permian gigantopterids is their similarity to

angiosperms and Gnetum in leaf architecture (Chapter III). This similarity has been

enhanced by some recent anatomical studies which revealed that Asian Gigantonoclea

and Gigantopteris leaves possess some anatomic features similar to those of

angiosperms (Li, H. and Tian, 1990; Guo et al., 1993; Li, H. et al., 1994c; also see

Chapter IV), and that American Delnortea bears comparison to modern Gnetum

(Mamay et al., 1988). In Chapter V, vessels have been found with scalariform

perforation plates in metaxylem or with foraminate-like perforation plate in

secondary xylem, respectively resembling those of primitive angiosperms and gnetophytes. All these vegetative features suggest that some gigantopterids may have a close relationship to anthophytes or they might have evolved, in parallel, into the anthophyte level.

However, the reproductive organs of gigantopterids have been studied very little. White (1912) assumed some seeds with a wing or bract belonged to G. americanum, based on their frequent and intimate association. He also attributed some polleniferous scales to the taxon. Asama (1959) hypothesized that gigantopterid lamina bore seeds like those of Emplectopteris, but smaller. He speculated that some black dots on gigantopterid leaves were seeds. Li, X. and Yao

(1983) reported both Gigantotheca and Gigantonomia as synangium-bearing and seed- bearing organs of gigantopterids, respectively. However, the Gigantonomia might actually not belong to the group (see following discussion for details). Yang (1987)

89 reported a different type of seed-bearing structure, but the connection between the seed and leaf was not demonstrated. Therefore, the reproductive organs of gigantopterids are still poorly understood.

I have found many compressed and permineralized seeds associated with gigantopterids. These include seeds collected from Wangjiazhai, Shuicheng, and

Yueliangtian, Panxian, western Guizhou, China. Twelve compressed seeds have been identified as Carpolithus speculatus. They are described below and compared with other seed plants to explore their potential relationship with gigantopterids.

DESCRIPTION

Twelve compressed seeds are found in similar ovate (Fig. 150) or ovoid (Fig.

152, the lower one) shapes. They are 9-11 mm long, 3-4 mm thick, and 5-6 mm wide. Some of them have a shallow sinus on one side, so that they are slightly bean­ shaped (Fig. 152, the upper one; Figs. 154-156). Most of them have been entirely

(Figs. 149-150) or partially (Figs. 154-156, arrows) surrounded by a narrow flat rim.

All these seeds exhibit rounded apices and bases. Their surfaces are characteristically smooth and shining.

Geological and geographical occurrence; Upper Permian; Wangjiazhai Mine,

Shuicheng, and Yueliangtian Mine, Panxian, Guizhou, China.

DISCUSSION

Identification - Carpolithus speculatus was named by Mo (Zhao et al., 1980) for some compressed seeds collected from the Upper Permian of western Guizhou

90 and eastern Yunnan. The diagnosis of the species is translated below from Chinese:

Seeds ovoid, or ovate, slightly bilaterally symmetric, 10-16 mm

long, 6-8 mm wide; apex blunt or hebetate; a beak-like projection, 1

mm long and with a blunt base, on the top of the seed core; surface

smooth and slightly convex, especially at the upper part, but the basal

part relatively flat; seed core with a wing-like flat rim, 0.5-1 mm wide;

seed base rounded, not in cordate shape.

The specific name seems to have been named for the smooth and shining surface, based on both its Chinese and Latin names.

The present compressed seeds are collected from the same location. They are in the same size range, with a smooth and shining surface, entirely or partially surrounded with a flat rim. One seed in ovate shape (Fig. 150) is identical with one

(Zhao et al., 1980, pl. XV, fig. 6) of Mo's specimens, while the ovoid seed (Fig. 152) is similar to others of Mo's specimens. These characters, especially the smooth and shining surface, of the present seeds are well matched up with those of C. speculatus.

So, the present seeds can be identified as to the same species.

However, some minor differences should be mentioned here: Two seeds look more or less bean-shaped with a shallow sinus on one side (Figs. 154-156), the sinus may have been formed originally or deformed during fossilization. The projection on the seed end was described as a beak-like structure by Mo (Zhao et al., 1980).

While in the present material, the projection is considered as a short stalk, since

91 their ends are not tapering apically, but are often blunt, resembling the broken-face of a stalk. Otherwise, the present seeds are near identical to C. speculatus.

Carpolithus Wallerius is a form genus that includes different sized seeds in

ovoid, ovate, or fusiform shape. The seed surfaces are smooth or with wart-like or

other structures (Gu et Zhi, 1974). All seeds without sufficient characters to be

identified to other genera or to be established as a new genus, can be put into this genus (Gu et Zhi, 1974). This genus is loosely defined. Although C. speculatus is relatively well defined, it is invalid since it was not published in English. However, since no permineralized seed can be matched up with the species, C. speculatus can not be redefined or replaced with structurally preserved seed. Therefore, the specific name is still used to temporarily describe the present compressed seeds.

Associated permineralized seeds - Numerous permineralized seeds are found associated with gigantopterid leaves. Several seeds are smaller (but close to the size) than those of compressed C. speculatus seeds. They are globular or ovoid, about 3 mm in diameter, and their integuments are often poorly preserved. When the integument is relatively well preserved it consists of the endotesta, middle sclerotesta, and sarcotesta as well as a smooth epidermis (Figs. 158-159). One seed has a sinus on one side of the integument (about 100 /im thick), and has a middle membrane which separates the nucellus into two parts (Fig. 158). Another seed has a thicker integument (about 200 /im thick) and a deformed nucellus (Fig. 159). These seeds are similar to C. speculatus in their smooth surfaces, but they are smaller and without a flat rim.

92 A similar ovoid seed also has a three-zoned integument and a deformed nucellus. It also has a projection which looks like a broken stalk that makes the seed similar to those C. speculatus seeds with a stalk. However, this seed has no flat rim and it is very small, only 1.5 mm long and 1.2 mm wide (Fig. 161).

Another seed, 3 mm long and 2 mm wide, is associated with a leaf of

Gigantonoclea cf. hallei on the same slab. The integument is bilaterally asymmetric.

The middle right side is thickened, while the middle left side is slightly depressed.

The integument consists of only two zones, one inner zone (about 40 pm thick) containing 2-4 layers of parenchymatous cells, and a thick outer zone (about 200 p.m thick) consisting of 1-2 elongated, sclerified cells which are perpendicular to the seed surface. This seed has no flat rim, but a slit on its top (Fig. 160).

Two seeds have been found composed of a central fusiform corpus with wing­ like structures. Both seeds show their tangential sections parallel to their minor plane. One seed consists of a corpus, 0.5 x 1.5 mm, and two wing-like structures, 3 mm in span (Fig. 162). The corpus appears with a two-zoned integument, the inner zone is similar to that of the seed in Fig. 160, but the outer zone is compressed and extended into the wing-like structures basically and distally. Another seed (Fig. 163) is little bigger, with wing-like structures (4 mm in span) and a corpus (1.3 x 2 mm), and its integument was decayed and carbonized so that no integumental zones are distinguishable. These seeds are smaller than those compressed C. speculatus seeds, but all of have a flat rim, although the rim of the latter is smaller and shorter.

Considering the wider wing-like structure, these two seeds are similar to that of

93 Carpolithus glansiformis Mo (Zhao et al., 1980), but the latter is much bigger (upper to 3 cm long).

Therefore, although several types of permineralized seeds have been found associated with gigantopterid leaves, none of them can be well matched with the compressed Carpolithus speculatus seeds.

Reconstruction -- Among all seeds found in western Guizhou and eastern

Yunnan, Carpolithus speculatus is the most abundant (Zhao et al., 1980). This matches with the dominance of gigantopterids that occurred in 87% of the plant- bearing layers in the Upper Permian strata (Yao, 1983a). Both C. speculatus and gigantopterids occurred most abundantly, and this fact suggests some relationship between them.

Geographically, Carpolithus speculatus has also been found in the Gigantopteris flora in Fujian, southern China (Huang, L. et al., 1989). A similar association has been found with specimens collected from Shanxi (= Shansi), northern China. One specimen has a gigantopterid leaf (Fig. 164) which was identified as G. nicotianaefolia by Halle (1927). The gigantopterid has been emended as Gigantonoclea hallei by Gu et Zhi (1974). Four seeds were found associated with the leaf when I recently re­ examined the specimen. One seed is globular, 7 mm in diameter (Fig. 168); two are ovoid, 8 X 5-6 mm (Fig. 165 lower; Fig. 166); and another is elliptical, 6 x 3 mm (Fig.

167). These seeds are generally comparable with C. speculatus in size and shape, as well as a short projection at one end. These seeds may belong to G. hallei.

94 In the southern region of northern China, a round seed, about 5 mm in diameter, has been reported on a secondary vein of a Gigantonoclea colocasifolia leaf on its abaxial surface (Yang, 1987). Since the greater part of the seed was still covered by the lamina, the real connection between the seed and the leaf was not demonstrated. Nevertheless, the association and the general appearance of the seed is similar to those of C. speculatus. Such a widely geographic association between gigantopterids and the similar seeds suggests that they may be related.

In western Guizhou, many Permian plant groups are often found selectively preserved together. In other words, different groups or species are often concentrated in some layers of sediments, sometimes mixed with a few other taxa.

This suggests that the leaves might come from the same niche or even the same plants, so that their associated reproductive organs have a high potential for belonging to the same plants as the leaves. Gigantopterids are plants whose leaves were often found abundantly deposited in the same sedimentary strata, although sometimes mixed with a few specimens of other taxa. For example, the rock specimen No. PLY02, about eight kilograms weight, contains hundreds of permineralized gigantopterid leaf pieces, stem segments, and some permineralized seeds, as well as hundreds of synangia. It has only a few pieces of taeniopteroid and

Pecopteris leaves mixed together, mostly on the top part of the specimen.

Similarly, the compression seeds of Carpolithus speculatus were found mostly between the Gigantopteris leaves or on the same slab as gigantopterid stems (Fig.

152), and usually not mixed with other leaf taxa. This intimate association implies

95 that both might belong to the same plants. Through careful dégagément, some seeds have been found beneath the abaxial surface of Gigantopteris leaves (Figs. 149-150,

153-155). Most of them are broken so that no stalk remains. Only four seeds have been found with a short stalk, which is about 0.5 mm both in length and width (Figs.

149-150, 153-155). Two of them are found beneath Gigantopteris leaves, and they have a stalk next to a basal primary vein (Fig. 150) or a secondary vein (Fig. 149).

The third one was preserved with its stalk closely pointing to a secondary vein of a gigantopterid leaf (Figs. 153-155). The stalks of the above three seeds do not directly attach the veins, but figures 156-157 show a seed with its stalk perpendicularly attached to a cross section of a leaf. The leaf was decayed and compressed to be a very thin carbon layer (about 25 pm only). The seed attaches a vein which is similar to another vein on the left side (Figs. 156-157). The right side of the leaf can be traced to a large flat portion of a broad leaf with several pinnate veins, which can be identified as secondary veins. Although no venation details are available to identify the leaf to a generic level, its width and the pinnate secondaries suggest it belonging to gigantopterids. Similarly, the vein attached with the seed should be a secondary vein of the gigantopterid leaf. It seems unlikely that all of these four seeds were just accidentally dropped with their stalks so close or on top of gigantopterid leaf veins. Therefore, it is not illogical or unfounded to suggest a potential relationship between these C. speculatus seeds and gigantopterid or

Gigantopteris leaves. In other words, these seeds might grow on the major veins of

96 gigantopterid leaves on the abaxial side, although this connection has not been verified anatomically.

Comparison - In order to examine the potential relationship, it is necessary to compare C. speculatus with other ovuliferous plants from the same flora or other contemporaneous floras. The Late Permian flora of western Guizhou contains roughly 200 plant taxa (Zhao et al., 1980; Tian and Zhang, 1980; Tian et al., 1990).

About 100 taxa belong to an artificial, mixed group, “Filices et Pteridospermopsida”

(Gu et Zhi, 1974). About 40 of them are gymnosperms, including cycads, ginkgophytes, conifers, and isolated seeds. Among the remaining 60 taxa, only a few have been found associated with gigantopterids. Taeniopteris, Fascipteris,

Compsopteris, Problechnum, Pecopteris, Rajahia, and Neiiropteridium are the leaf form genera that occur relatively often mixed with gigantopterids.

Compsopteris, Problechnum, Neiiropteridium, and Fascipteris are taeniopteroid plants since they are more or less similar to Taeniopteris in their large compound leaf with long-elliptical to broadly-linear pinna and their similar venation. Sometimes it is difficult to distinguish them from each other, especially when only a broken section of a blade is found and the venation is unclear. Recently, Compsopteris (including

Problechnum', Gu et Zhi, 1974), Neuropteridium and Taeniopteris are suggested to be congeneric with Qasimia which is a synangium-bearing leaf genus of Marattiales

(Wang, H. and Yang, 1995). However, in western Guizhou, Compsopteris leaves have often been found associated with some isolated seeds identified as Samaropsis sp., and both may belong to the same plants (Tian and Zhang, 1980). The seeds are

97 ovoid in shape, about 40 mm long and 15 mm wide. The sarcotesta is about 3.5 mm wide and preserved into a wing-like structure. These seeds are similar to those of

Carpolithus glansiformis Mo (Zhao et al., 1980) from the same area, in size, shape, and structure. In my collections, only one elliptical seed is more or less similar to the above two taxa, but it is smaller (only 21 mm long and 12 mm wide) and it is associated with a piece of taeniopteroid leaf as well as some gigantopterid foliar fragments. So, if Compsopteris is a seed plant, it would be more likely related to

Samaropsis sp. or C. glansiformis rather than to C. speculatus.

Mei et al. (1992) consider Taeniopteris as a form genus that accommodates taxa of both pteridosperms and cycads. One type of taeniopteroid lamina,

Eophyllogonium, from Jiangxi Province, has been reported with simple anastomosing venation and marginal seeds, 1.2 x 0.8 mm to 1.9 x 1.9 mm in size (Mei et al., 1992).

Another type of taeniopteroid leaf is Gigantonomia, which also bore small seeds, 2.5

X 1.5 mm, nearby the margins (Li, X. and Yao, 1983). In North America,

Taeniopteris has been found attached to Phasmatocycas (Gillespie and Pfefferkorn,

1986) and treated as cycads by Mamay (1976). The seeds of Phasmatocycas were found bilaterally along the basal part of the blade, and they are crowded into more or less rhomboid shape. The present C. speculatus seeds are obviously different from

Phasmatocycas seeds in shape and may not be related to cycads.

Fascipteris was also a form genus, established by Gu and Zhi (1974). Some

Fascipteris species have been found with Ptychocarpus synangia (Gu and Zhi, 1974), but no seeds have been found on Fascipteris leaves. Some Fascipteris-like pinnules

98 with seeds have been found from Henan Province, China and identified as

Fascipteridium (Zhang and Mo, 1979). The seed impressions are oval, 3.5 x 2.5 mm,

and also have a narrow marginal rim and a smooth surface (Table 9). However,

these seeds are smaller than Carpolithus speculatus, and occur near the margin of the

pinnules, with their long axis parallel to the secondary veins. Fascipteridium has not

been reported from Guizhou, and it is hard to suggest any relationship between C.

speculatus and Fascipteridium at the present time.

Pecopteris is another foliage form genus which includes leaves of both

marattialean ferns and seed ferns. In western Guizhou, about 30 Pecopteris species

have been reported (Zhao et al., 1980; Tian and Zhang, 1980; Tian et al., 1990), but

none have been found with seeds. In my collections, some associated Pecopteris

fronds have been verified as belonging to the Marattiales, as evidenced by the

attached synangia (see Chapter VII). In Northern China, Halle (1929) found

Pecopteris wongii, from Shanxi, with flattened ovate seeds, 7 x 4 mm, connected to

the main rachis of a frond by a thick recurved stalk (Table 9). Zhang and Mo (1979)

reported Pecopterispunicoides from Henan bearing spherical seeds, 11 x 10 mm, with basal and apical projections, and the apical projection with two pointed horns (Table

9). These seeds are clearly unlike the present C. speculatus seeds.

Other possible seed plants, such as Cladophlebis,Alethopteris, Sphenopteridium,

and Sphenopteris, that occur in the western Guizhou flora are rarely found associated with gigantopterids. None of them have been reported with seeds, except for

99 Cladophlebis parapermica and C. fuyuanensis and their seeds are different from the present Carpolithus speculatus in size and shape.

Some isolated gymnospermous seeds have been found from the Permian flora in western Guizhou. Squamocarpus seeds are tetragonal in cross section (Zhao et al., 1980). Cardiocarpus, Gigantospermum, and Rhabdocarpus are usually very big,

2 - 7.5 cm long and 1.5 - 5 cm wide (Tian and Zhang, 1980; Zhao et al., 1980), while

Carpolithus minutus seeds are very small, only about 2 x 1 mm in size (Zhao et al,

1980). In short, none of these seeds from western Guizhou or other Cathaysian floras are identical with the present C. speculatus seeds.

On the other hand, permineralized seeds of my collections can not be matched with the compressed Carpolithus speculatus, but they are also not comparable with other structurally preserved Cathaysian seeds reported by Li, Z.-M.

(1990, 1991, 1993b). Therefore, these permineralized seeds should be further studied, to reveal their systematic affinities. In short, C. speculatus seeds may not belong to other associated plants, and they were possibly produced by their associated gigantopterids.

Beside the above Carpolithus speculatus, two unusual, possibly reproductive, structures have been found on the counterpart of figure 69 in my collections. The specimen (Fig. 151) contains two gigantopterid leaves. One is an actinodromous leaf

(Fig. 69, Fig. 151 right), exhibiting the well preserved compound mesh venation of

Gigantopteris meganetes. Another leaf shows its major vein skeleton with very poorly preserved lamina (Fig. 151 left). The major vein is slightly curved to the right side

100 and has prominent descending secondary veins on left side. It is identical to the

basal primary vein of the associated G. meganetes leaf, and this leaf may belong to

the species too. On the abaxial side of this basal primary vein, there are two

complex structures extended to right side (Fig. 151). Each structure consists of a

stalk (7-8 mm long; Fig. 151 arrows) and a spoon-like structure (5-6 mm long).

Both stalks start from the basal primary vein, sub-alternatively with the descending

secondary veins, in a little flattened solid form, about 0.3-0.5 mm wide. The lower

stalk had been removed, and a fresh broken-face was exposed without a sedimental

matrix covering it. These facts suggest the two stalks may have originated from the

same vein. The stalk turned into a V-shape on its transection, and it gradually

reached to 1.5 mm in half-width viewing from one side. Then, it changes into a

spoon-like structure consisting of at least three bract-like (or cupule-like?) structures

of different sizes. The bract-like structure at the basal side is the smallest, about 3 mm long, and appears to be a scale foliage with a curved apex which is about 1.5 mm

long. Other bracts are about 5-6 mm long. One such bract-like structure had been also removed, and a smaller overlapped portion of a carbonized smooth structure has been exposed (both the lower stalk and the bract-like structure have been replaced back to their original places now). It is hard to tell if the overlapped portion is a seed, another bract-like structure, or a vegetative bud. This new type of possible reproductive organ has not been identified as a new taxon, since their structures are not well understood. It is also unknown at the present time whether they represent a type of reproductive structure, or just some adventitious vegetative buds.

101 Conclusion -- Considering that gigantopterids include many leaf types

(Chapters III and IV) and at least two stem genera, this group may also have several

types of reproductive organs. Among all gigantopterids, C-type has been suggested

as seed fern since their stomata look like some seed ferns (Yao and Crane, 1986;

Yao and Wang, 1991). While E-type De/norfea has been suggested to be comparable

to Gnetum, based on the vegetative structure (Mamay et al, 1988). However,

reproductive organs have not been found in both C-type and E-type gigantopterids,

but in G-type.

Carpolithus speculatus seeds seem to be just one of them, and they might be

produced by Gigantopteris, since their associated leaves have compound mesh

venation, when the leaves were well preserved.

A taeniopteroid seed-bearing specimen has been reported as Gigantonomia,

which is reportedly con-specific with Gigantonoclea fukienensis (Li, X. and Yao,

1983). Gigantonomia consists of seed-bearing taeniopteroid leaves on the upper part

of a rachis and sterile Gigantonoclea fukienensis leaves on the lower part (Text-Fig.

1 and Fig. 1, pi. 1 in Li, X. and Yao, 1983). However, both the upper and lower parts of that specimen are actually overlapped on different planes and are not

organically connected (Yao, personal communication, 1987). Considering the fact

that gigantopterids are found relatively often associated with taeniopteroids, it is hard

to exclude the possibility that the fertile taeniopteroid leaves might be accidentally

overlapped on the G. fukienensis leaves. Furthermore, those taeniopteroid

Gigantonomia blades did not show any reticulate venation as that in the G.

1 0 2 fukienensis. Although the relationship between the taeniopteroid Gigantonomia and

G. fukienensis is not confirmed, it is still possible for some gigantopterids to have

taeniopteroid-like reproductive leaves, since a few gigantopterids {e.g., Gigantonoclea longifolia) have very long lanceolate leaves that are similar to those taeniopteroid

leaves.

Eophyllogonium appears to be a similar taeniopteroid leaf that bore seeds on

the margins, and with elongated simple meshes. These leaves are more or less

similar to the venation of their associated gigantopterids. Wan (1984) described the

leaves as gigantopterid reproductive organ. However, they were latter suggested to represent an independent group (Mei et al, 1992). More studies should be conducted in future to test the relationship between Gigantonomia or Eophyllogonium and gigantopterids.

In short, although gigantopterids have been suggested as belonging to seed plants by different authors, their seeds have not been well demonstrated. Only some impressed and/or compressed seeds or seed-bearing organs have been reported belonging to G-typed gigantopterids, with a certain amount of speculation. These include Gigantonomia, Carpolithus speculatus, and Eophyllogonium. They are very different, in terms of seed size, shape, and attachment type. These suggest that the

G-type gigantopterids might be a special polyphyletic seed plant group, consisting of several different lineages. However, this conclusion still remains to be tested further with permineralized reproductive organs of gigantopterids.

103 CHAPTER VII

THE ASSOCIATED SYNANGIA

ABSTRACT

This chapter presents two types of permineralized synangia found in a single specimen that also contains numerous gigantopterid leaves and stems. One type of synangium was found abaxially borne on the secondary veins of a gigantopterid leaf.

Each synangium consists of up to 13-14 sporangia in two rows along the veins.

Palynomorphs are poorly preserved. This type is different from that of Gigantotheca and suggest that gigantopterids may represent a polyphyletic group. Another type is dominated among all isolated synangia. Each synangium is bilaterally symmetrical, up to about 2 mm long and 1 mm in diameter, and consists of a sporangia! portion on a hollow base with a short stalk on one side. Sometimes, some filament-like structures hang on the inner top walls of the hollow bases. The sporangial part is composed of a ring of 9-14 elongated sporangia laterally appressed around a central vascular column that does not extend to the apex of the synangium. Tracheids can be traced from the stalk, through the side and top walls of the hollow base, to the vascular column. Palynomorphs are poorly preserved, but a few of them exhibit a

104 furrow-like structure. This type differs from those of all known synangiate plants,

and probably belong to gigantopterids, based on their dominance and association.

INTRODUCTION

Gigantopterids have been studied since Schenk (1883), but their reproductive

organs have not been well understood. White (1912) assumed some polleniferous

scales belonged to Gigantopteridium americanum, but this assumption has never been

confirmed. Li, X. and Yao (1983) reported some compound synangia of

Gigantotheca paradoxa, which were abaxially borne on some gigantopterid leaves,

from the lower part of the Tongtzuyen Formation, Lower Permian. They suggested

that the compound synangia were pteridospermous in nature, based partially on the

discovery of seeds on some fertile gigantopterid leaves, Gigantonomia, from the upper part of the formation. Since their specimens were highly metamorphosed and carbonized, there is no detailed morphology available to support to their conclusion.

This chapter describes, for the first time, structurally preserved gigantopterid synangia in specimen No. PLY02 collected from the Upper Permian of western

Guizhou Province. The specimen contains abundant permineralized synangia associated with or attached to gigantopterid leaves. Two taxa have been established with discussion on their systematic attributions and evolutionary significance.

105 SYSTEMATICS AND DESCRIPTION

Order Gigantopteridales

Family Gigantopterldaceae

Genus GuizJioiUheca gen. nov.

Type species: Guizhoiitheca inanibasis.

Guizhoutheca inanibasis gen. et sp. nov.

Diagnosis: Synangia bilaterally symmetrical, 1.5-2.1 mm long, 450-500/im (up

to 1 mm) in diameter, with a ring of 9-12 (up to 14) elongated sporangia on a hollow

base; the base about 1/3 length of the synangia, with a short stalk attached on one

side and sporangia slightly bending to the stalk side; sometimes some filament-like

structures extending down from the inner top wall of the hollow basal chamber;

sporangia, up to 1.2-1.5 mm long and 200-400/rm in diameter, surrounding a central

vascular column and extending beyond the central column distally; sporangia radially

symmetrical at their middle cross section; sporangial tips flaring outward or bending

over the central hollow area to some extent; the central vascular column with 1-6

lacunae in vascular tissue; tracheids extending from stalk, along basal chamber side

and top walls, to entering the central vascular column; external sporangial walls two

or three cells thick; inner and radial walls one cell thick; palynomorphs ovoid, 15-30

/im in diameters, with large papillae and/or a furrow-like aperture.

Etymology: The generic name of Guizhoutheca is proposed after the locality

of Guizhou Province, plus the suffix -theca, sporangium. The specific name

106 inanibasis is composed of Latin inanis (= hollow) and basis (= base) to underscore

the synangium with a hollow base.

Holotype: Specimen No. PLY02, slides #C4(R), #C4-4, #C4-5, and #C9(L);

Figures 171-174 in this dissertation.

Paratypes: Specimen No. PLY02, slides #C6, #C7(2T-1), and #C9(T)-1;

Figures 169-170 and 176-177 in this dissertation.

Type locality: Yueliangtian Mine, Panxian County, Guizhou Province,

China.

Type horizon: Xuanwei Formation, Upper Permian.

Age: Longtanian to Changxingian, Late Permian.

Description: Synangia - Most isolated synangia are commonly 450-500 fxm in diameter and about 1.5-1.8 mm long (Figs. 173-174), but some larger ones can be up to 1 mm in diameter and 2.1 mm long (Figs. 169-170), and a few smaller ones are just about 1 mm long (Fig. 176). Each synangium consists of a sporangial portion on a hollow base (Figs. 170, 173-176). Sporangia are slightly bent to one side (Figs.

169-170, 174).

Each synangium is composed of a ring of 9-12 (up to 14) elongated sporangia which are laterally appressed around a central vascular column (Figs. 171-172, 175-

176). A hollow central area is formed distally, since the central column is shorter than surrounding sporangial apices (Figs. 169-170, 173-174, 176). Sporangia are arranged from 0.5 (Fig. 176) to 1.5 (Fig. 170) mm long, and 200 (Figs. 173-174) to

107 400 fxm in diameter. Distally, sporangial tips are blunt or rounded and flared outwards (Figs. 173-174) or slightly incurved (Fig. 170). The inner and radial sporangial walls appear to be single layered, while external sporangial walls are often carbonized and seem to be two or three cells thick (Figs. 171-172 ). The sporangial dehiscence mechanism is not understood at this time.

The central column contains 1 to 6 lacunae (Figs. 171-172) among parenchyma and tracheids which have helical thickenings. Vascular tissue can be traced from the short stalk, through the side and top walls of the basal chamber, to the central vascular column. The bases measure up to 0.7 mm long and 1 mm in diameter (Figs. 170, 173-174). Basal chambers are commonly empty, but sometimes contain some filament-like structures, 10-13 /xm in diameter, hanging on the inner walls of the basal chambers (Figs. 170, 176-178). Considering the above features, a synangium reconstruction has drawn in Fig. 178.

Figure 179 shows an interesting structure which measures 400 x 600 iim on its oblique section. It consists of a three-zoned side wall and a hollow chamber with the middle zone dissolved by HCl solution. The structure has a smooth inner surface and contains some worm-like structures mixed with crystals. This structure is suggested to be the basal part of a G. inanibasis synangia (see discussion).

Palynomorphs - Palynomorph is a general term including microspores, prepollen and pollen in fossil records. It is used here because the male reproductive particles in the synangia are poorly preserved, and it is hard to determine whether they are microspores or pollen, although they look like pollens to some extents.

108 Each sporangium contains thousands of palynomorphs. The palynomorphs, macerated out from the synangium of Fig. 174, are commonly spherical or ovoid, 13-

16 X 15-20 ju,m, and crowded. Their walls are often broken with some large window­ like holes (Figs. 180, 184). It is unknown whether this damage was formed before or during diagenesis, or caused by the rapidly releasing air bubbles during maceration. Occasionally, some well prepared small individual palynomorphs were observed under the light microscope. They are about 11 x 17 /xm in size and have relatively very thick walls bearing one to several papillae which are about 3 /xm tall and 4 /xm in diameter (Fig. 181). These papillae appear fragile, so that the window­ like holes might be caused by their breaking. The palynomorph walls are up to 4 /xm thick, consisting of a 3 /xm thick middle layer and two thin layers covered on both inside and outside. Two palynomorphs, 8 x 14 /xm (Fig. 182) and 28 x 30 /xm (Fig.

183), do not have papilla, but they have a furrow-like structure which may be an aperture. A palynomorph, 20 x 25 /xm, also with a furrow-like structure was found under the SEM, and it has two slightly expanded ends that may be two un developed or reduced sacci (Fig. 185). Therefore, these palynomorphs appear to be pollens.

The present palynomorphs are different from those of previously reported spores and pollens from the region (Ouyang, 1982, 1985; Ouyang and Li, 1980).

Further detailed study on these in situ palynomorphs of Guizhoutheca would provide more information for us to determine their nature.

109 Guizhouthecal sp.

Description: Synangia -- In total six elongate synangia have been found preserved together into one slanted row (Figs. 186-188). Fig. 187, which was

prepared with peel technique, shows only four synangia. No. 2 -4 and No. 6, and a part of cross section of a gigantopterid leaf with a tertiary vein (arrow). Figure 186 was directly photographed from the slab. Since the slab had been deeply etched with

1% HCL for about 20 minutes and peeled once, the outlines of the cross section of

the lamina, veins, and synangia are not very clear. In Figure 186, all six synangia

have been cut through, although No. 5 and No. 6 have just a little part cut through

(only 6 and 5 sporangia were exposed respectively. Fig. 188). The laminar section in Fig. 187 can be traced to a very thick secondary vein that is attached with synangium No. 5. The secondary vein is paralleled with another secondary vein which is attached with synangium No. 6. Other synangia show 12-14 sporangia in each (Fig. 188). A restoration of the specimen has been drawn in Fig. 188, based on observations on the slab and Figs. 186-187. The leaf was poorly preserved, but can be identified to gigantopterids since its uniquely large lamina and folding status can be comparable to some folded gigantopterid leaves (Fig. 189). Although the leaf can not be identified to generic level, it must be a Gigantopteris or Gigantonoclea species since no other gigantopterid genera have been found in the rock specimen.

Synangia are parallel with secondary veins of the gigantopterid leaf.

Considering the oblique section of the veins (Fig. 186), the synangia might also be obliquely cut through. Each synangium, up to 2.3 mm long, consists of 12-14

110 sporangia arranged in two rows, but this may be a deformation (see discussion below). Sporangia are about 200-400/xm in diameter in the oblique transection, and their actual diameters might be a little smaller (Figs. 186-188). These synangia were partially cut off during preparation, but the remained parts are longer than 500 /xm.

Palytiomorphs -- The attached synangia have numerous palynomorphs. They are poorly preserved, mostly with window-like holes, so that they are roughly similar to those of Guizhoutheca inanibasis. However, there are no well preserved palynomorphs available to be compared with those of G. inanibasis.

DISCUSSION

Assemblage -- The specimen No. PLY02 contains hundreds of permineralized gigantopterid leaves and stems, and a few pieces of pecopterid (Figs. 191-193) and fascipterid pinnules. Four types of synangia have been found in the specimen. One type consists of four sporangia fused laterally, and this type is separately preserved.

In another specimen No. L9406, this type of synangium has been found arranged in a single row borne on either side of the midrib of a pecopterid pinnule (Figs, 194-

195). The spores are trilete, spherical, 30fxm in diameter, with narrow rugulate sculptures (Figs. 196-197). This type of synangium can be identified to as

Scolecopteris. The C-shaped vascular tissue in the pecopterid rachis (Fig. 193) also suggests a marattialean frond (Taylor and Taylor, 1993).

Another minor type of synangium is also separately preserved in the specimen

PLY02. Synangia are similar to the above Scolecopteris synangia, but each consist

111 of 5-6 laterally fused sporangia (Fig. 190). These synangia can be compared with those on Fascipteris {Ptychocarpus) densata, a taeniopteroid type of pinnule found in the Upper Permian of Jiangsu, Guizhou, and Tibet (Gu and Zhi, 1974).

The third type is the synangium of Guizhoutheca! sp. that is attached to a gigantopterid leaf. However, only six such synangia have been found. This is not equivalent to the dominance of gigantopterids among all associated foliar pieces.

The fourth type is the isolated synangium of Guizhoutheca inanibasis. More than

95% of synangia in No. PLY02 belong to this type. This large ratio is well matched up with the majority of the associated gigantopterid leaves and suggest their possible correlation. Thus, Guizhoutheca! sp. has organic connection with a gigantopterid leaf, while G. inanibasis is quantitatively matched up with gigantopterids and suggested to belong to gigantopterids also.

Morphologically, Guizhoutheca! sp. synangia appear to be different from those of G. inanibasis, since their sporangia were preserved in two rows rather than in a ring. However, their sporangium number and diameter are the same as those of the latter. Their palynomorphs are also roughly similar to each other. So, both may be related or belong to the same genus. Therefore, this attached type has been temporarily named as Guizhoutheca! sp., with a question mark after generic name to reserve the uncertainty.

On the other hand, some isolated synangia appear to have been bilaterally appressed so that their central columns were narrowed and elongated (Fig. 175).

Sometimes, the column would be pressed into a thin layer, while the sporangia would

1 1 2 be pressed from a ring shape into two rows (Fig. 175). The sporangia of

Guizhoutheca? sp. are arranged irregularly so that they look bilaterally appressed as

the leaf was adaxially folded during the burying and pressing processes. No basal

part and central vascular column have been found. The base may have been cut off

during the preparation and the central column may have been crushed during

fossilization, or both did not exist at all. Thus, it is difficult to determine whether

this two-rowed sporangium might be deformed from a ring-shaped synangium of G.

inanibasis or originally be in that way. The real relationship between G. inanibasis

and Guizhoutheca? sp. should be further examined in future.

The correlation between these synangia and gigantopterid leaf taxa is not

known at this time. Gigantopterids in Guizhou include at least two genera,

Gigantonoclea and Gigantopteris, and several species in each. Similarly, Guizhoutheca inanibasis and Guizhoutheca? sp. might actually represent synangia of all or most gigantopterids of the flora. The isolated synangia are not exactly the same, and they vary in size {eg., from 0.5 mm to 2.1 mm in length) and form (e.g., with flared or incurved sporangial apices). These differences may correspond to different gigantopterid taxa.

Comparison with Gigantotheca - Guizhoutheca? sp. is comparable to

Gigantotheca paradoxa, the only synangium-bearing gigantopterid, reported from the

Early Permian, Fujian Province (Li, X. and Yao, 1983). Gigantotheca has a large ovate leaf with compound synangia. Each compound synangium consisted of two synangiate bands arranged bilaterally along the secondary veins. Each synangium

113 consists of up to 16 pairs of sporangia along the tertiary veins and was interpreted

as being covered with an indusium. Sporangia contain spherical microspores with

triradiate scars. Although Gigantotheca was suggested as belonging to a seed fern

by Li, X and Yao (1983), it is generally similar to the marattialean ferns, particularly

to those of Eoangiopteris goodii (Millay, 1978), in terms of the bilaterally symmetrical

synangia, their bilateral position along the veins, and possibly trilete microspores.

Some Early Permian C-type gigantopterids are more or less similar to

Taeniopteris in leaf shape, venation, or both. Taeniopteris, however, is a form genus

and may include plants of different groups. Mesozoic Taeniopteris has been

associated with cycadeoids. In the Paleozoic, some Taeniopteris species were

suggested to be related to cycads, based on some seeds found on the abaxial surface.

Some taeniopterids pinnules (e.g., Compsopteris, Problechniim, Neiiropteridium and

Taeniopteris) may belong to marattialean ferns, because of the marattialean-type synangia found on the pinnules (Hill et al, 1985; Li, X. et al, 1982b; Mamay, 1976;

Wang, H. and Yang, 1995). If C-type gigantopterids have been found with marattialean-type synangia, it would be not too surprising, since their foliages are similar. Gigantotheca is a large ovate leaf, and should belong to G-type gigantopterid. Despite its marattialean-type synangia, Gigantotheca was suggested to be a seed plant, because a G-lype Gigantonoclea fiikienensis was reported connected to a seed-bearing gigantopterid leaf, Gigantonomia (Li, X and Yao, 1983).

However, Gigantonomia is a sterile leaf in taeniopteroid form, which may not actually connect G. fukienensis (see Chapter VI) and is not found from the same

114 strata as Gigantotheca. Both Gigantonomia and Gigantotheca may belong to different groups, so the nature of Gigantotheca should not be determined by Gigantonomia.

In other words, whether Gigantotheca is related to Marattialean or seed ferns should be re-examined, based on its own features.

Synangia of Guizhouthecal sp. appear with sporangia in two rows and are also on the abaxial side of a gigantopterid leaf. These make Guizhouthecal sp. similar to Gigantotheca. However, the former have simple synangia without indusia, while the latter have compound synangia covered by indusia. In addition to these, no trilete microspores has been found in sporangia of Guizhoutheca? sp. Therefore, synangia of Guizhoutheca? sp. are very different from those of Gigantotheca paradoxa.

On the other hand, the isolated synangia of Guizhoutheca inanibasis are characterized by their hollow base and a ring of sporangia, and thus obviously different from those Gigantotheca synangia, which are composed of sporangia in two rows.

Systematic attribution of Guizhoutheca? sp. - The discovery of synangia is significant in determining the affinity of gigantopterids, because synangia are only found in Psilophyta (Psilotum and Tmesipteris), Marattiales, Cycadeoidophyta, and seed ferns (Gifford and Foster, 1989). Psilophytes have very small leaves and are incomparable with the large-leafed gigantopterids. Cycadeoidophytes differ from gigantopterids by their parallel venation rather than reticulate venation.

115 Many Paleozoic and Mesozoic marattialean ferns have been found with various synangia. Almost all of them have their synangia arranged in rows on either

side of the midrib on the abaxial surface of the pinnule. There are two types of synangia in terms of symmetry. One type is radial symmetrical, such as that found

in Scolecopteris, Cyathotrachiis, Acaidangium, Araiangitim, Acitheca, and Sturiella

(Millay, 1977, 1979, 1982a, 1982b, 1982c; Lesnikowska and Millay, 1985; Zhao, L ,

1991; Lesnikowska and Galtier, 1991; Delevoryas et al., 1992). The second type is

the bilateral symmetrical, and occurs in Eoangiopteris goodii (Millay, 1978),

Granduryella renaultii (Lesnikowska and Galtier, 1992), and Pectinangiiim (Wan and

Basinger, 1992). Pectinangium is from Southern China, and each synangium has only four sporangia. The synangia of G. renaidtii are composed of 6-10 sporangia in two rows, while E. goodii has synangia arranged closely parallel, and each synangium is in linear shape in cross-section and is composed of 10-19 sporangia in two rows; spores are spherical with trilete suture.

The synangia of Guizhouthecal sp. have two-rows of sporangia and look superficially similar to the those of Eoangiopteris goodii and Granduryella renaultii.

Although the former might be bilaterally appressed from a ring of synangia (see

above), and no trilete palynomorphs have been found from its synangia, more details are needed to determine whether it is related to Marattiales.

Systematic attribution of Guizhoidheca inanibasis - The isolated synangia of

Guizhoutheca inanibasis are similar to radially symmetrical marattialean synangia in that all of their sporangia were arranged into a ring. However, Guizhoutheca

116 synangia are different in following aspects: First, they are actually bilateral symmetrical because their base and the apices bend to one side, and the stalk is located on the base on the same side. In comparison, marattialean synangia have straight sporangia and the pedicle, if preserved, is at the basal center. Second,

Guizhoutheca has up to 14 sporangia in each synangium; while marattialean synangia have fewer sporangia, mostly 3-6, and Scolecopteris altissimus has 5-9 sporangia

(Millay, 1982a). Third, marattialean sporangia are laterally appressed or fused at the base, lower part, or a longer portion of their length; the sporangial top parts are free from each other. However, Guizhoutheca sporangia seem to be appressed all the way, except at the very tips. Fourth, the Guizhoutheca synangium has a long and complex central vascular column which also contains one to several lacunae. In marattialean synangia, the central column is either absent, very short, or consists only of parenchyma cells {e.g., Scolecopteris altissimus, Millay, 1982a; S.globiforma, Millay and Galtier, 1990). Fifth, Guizhoutheca synangia have their characteristic hollow base, which does not occur in marattialean synangia. In short, these features indicate that G. inanibasis is different from marattialean ferns.

Synangia are also characteristic in three major Paleozoic pteridosperm groups,

Lyginopteridales, Medullosales, and Callistophytales, except for some primitive lyginopterids (Halle, 1933, 1937a; Millay and Eggert, 1970, 1974; Millay and Taylor,

1977, 1978, 1979; Stidd and Hall, 1970; Stidd et al., 1985; Taylor and Taylor, 1993;

Matten and Fine, 1994). These synangia can be divided into three types: simple, aggregate, and compound (Millay and Taylor, 1977, 1979; Matten and Fine, 1994).

117 Guizhoutheca inanibasis synangia can be compared only with the simple type. The simple pteridosperm synangia have been found borne either on branching systems

(e.g., Telangium, Feraxotheca in Lyginopteridales), or on the abaxial side of pinnules

(e.g., in Callistophytales). 0 . inanibasis synangia are similar to the simple synangia of Feraxotheca (Millay and Taylor, 1979) and Telangfum schweitzeri (Matten and Fine,

1994) in their bilateral symmetry and sporangial ring. The sterile bases of these lyginopterid synangia are similar to the hollow base of Guizhoutheca in teims of the volume ratio of the base to the sporangia. However, these sterile bases are neither hollow nor filled with filamentous structures. The base of Feraxotheca contains parenchyma cells, while the base ofT. schweitzeri has no parenchyma preserved but vascular tissue. Both have no central column.

Guizhoutheca inanibasis synangia are also similar to callistophytalean synangia

{e.g., Callandrium, Stidd and Hall, 1970; Idanothekion, Millay and Eggert, 1970) in the following aspects: location on the abaxial surface of a lamina, a central vascular column, and a central hollow area above the column. Nevertheless, these callistophytalean synangia are radially symmetrical, and are not borne on a hollow base.

Guizhoutheca inanibasis synangia are not identical with the above pteridosperm synangia, but seem to be combined with features of both Feraxotheca and Idanothekion, two highly evolved seed ferns. The central vascular column resembles that of Idanothekion, while the hollow base is similar to the sterile base

118 of Feraxotheca, but the latter is solid. Therefore, G. inanibasis appears to be more

elaborate.

In conclusion, Guizhouthecal sp. has been found attached to a G-type

gigantopterid leaf. Guizhouthecal sp. is similar to those of Gigantotheca, but the

latter are compound covered with indusia. These different synangia of G-lype gigantopterid suggest again that gigantopterids may be a polyphyletic group. Both

Guizhouthecal sp. and Gigantotheca have their sporangia arranged in two rows, thus they are comparable to those marattialean plants. Their systematic relationship to

Marattiales should be further examined. Guizhoutheca inanibasis synangia are generally comparable with those of seed ferns, but differ from all known pteridospermous synangia in their central vascular column and hollow base. G. inanibasis synangia are suggested to belong to the G-type gigantopterids, because they quantitatively matched up with the dominant gigantopterid leaves among the associated leaves. However, no in situ synangia have been found on gigantopterids, and it is far uncertain whether both G. inanibasis and Guizhouthecal sp. are the same synangium type preserved in different forms. These aspects and their palynomorphs remain to be further examined in future.

119 CHAPTER VIII

THE PALEOPHYTOGEOGRAPHY OF GIGANTOPTERIDS

ABSTRACT

Four major Late Paleozoic floras, the Euramerica, Cathaysia, Angara, and

Gondwana, have been traditionally recognized. Since gigantopterids are characteristic of the Cathaysian flora and also found in western North America, both floras have been commonly called the Gigantopteris floras. For these reasons, the western North America vegetation has been classified differently by different authors.

This chapter presents a brief classification of Permian floras with a focus on the

Cathaysian Region, which includes three provinces: South China, North China, and

Tarim-Qilianshan. To recognize the distinct gigantopterid vegetation in both Asia and North America, the Gigantopterid Biome is proposed as a non-systematic phytogeographical category, to include Permian and probably Early Triassic floras of South and North China Provinces and Texas, USA. The Tarim-Qilianshan

Province is not considered part of the Gigantopterid Biome, since gigantopterids have not been found there. Possible migration pathways of gigantopterids between the two continents have been explored, and two new Permian world maps have also been reconstructed, based upon the plant megafossil data.

1 2 0 INTRODUCTION

The Late Carboniferous and Early Permian are important periods in plant

biogeography, since during this time smaller, regional floras began to differentiate

from earlier, more widespread floras. It is traditionally believed that at this time

there were four major floras in the world: 1) the Euramerica or Euramerian

(Western Europe and eastern North America) on the west paleo-equator; 2) the

Cathaysia Floras (China, Japan, Korea and southeast Asia) on the east paleo-

equator; 3) the Angara Flora in the northern hemisphere; and 4) the Gondwana

Flora in the southern hemisphere (Chaloner and Lacey, 1973; Chaloner and Meyen,

1973; Allen and Dineley, 1988; Chaloner and Creber, 1988; Cleal and Thomas, 1991).

The word “flora” has been traditionally used to refer to vegetation in various

areas, locations, and periods. A flora can be named after a locality {e.g., the above

four floras) or after the name of characteristic plants (e.g., Glossopteris Flora,

Gigantopteris Flora). However, as modern phytogeography develops, world vegetation has been systematically classified (Cronquist, 1982; Takhtajian, 1986). In

these systems, all vegetation is divided, into different hierarchical categories

(Kingdom, Subkingdom, Region, Province, Sub-Province, etc.), based on the characteristic floral patterns. The vegetation is plotted in a continuous territorial

region and named after its particular locality, eg., the Southeastern Chinese Province

in the Eastern Asiatic Region, the Rocky Mountain Province in the Rocky Mountain

Region.

121 To conform with modern phytogeography, the above four floras have

informally or formally been changed into different terms by different authors. For

example, Li , X. (1986) briefly designed them as four provinces; while Cleal and

Thomas (1991) revised the four floras into four paleokingdoms, plus a fifth

paleokingdom. North America.

These are two conflicting classifications, especially with regard to North

American vegetation. Cleal and Thomas's (1991) treatment appears to be consistent

with modern phytogeograhic classification, in the sense of territorial continuity.

However, compared with the other four contemporary floras, which are very large

and dominated by their unique plants assemblages, the size and floral nature of western North America does not appear to qualify as a kingdom category. On the

other hand, the newly named Cathaysia North American Subprovince by Li, X.

(1986) implies some confusing phytogeographic meanings. To set up a practical base, a brief paleophytogeographic classification is proposed below.

In general, the plant assemblages of the Euramerica, Cathaysia, Angara, and

Gondwana floras have been well recognized, and each has demonstrated its own endemic plants, especially during the Late Carboniferous and the Permian periods.

These major floras are no doubt qualified to be established as provinces or

Kingdoms. However, in western North America, only Permian plants are known and they are found in sporadic areas. The plant assemblages in these disparate floras are very complex. Four different floras have been reported in the region: 1), an Angaran type flora in central Alaska (Mamay and Read, 1984); 2), the Supia Flora on the

1 2 2 western side of the Rocky Mountains; 3), a Gigantopteris Flora in Oklahoma and

Texas; and 4), a Glenopteris Flora in central and southern Kansas (Read and Mamay,

1964). The phytogeographic affinity of these small floras has been problematic. The

Glenopteris Flora is similar to the Euramerica Flora, the Supia flora and the central

Alaska floras might be related to the Angara flora, while the Gigantopteris Flora is

the most enigmatic (see discussion below). These floras are possibly unrelated, in

terms of phytogeographical origin. Therefore, these small floras do not deserve a category of Paleokingdom, compared with the other four kingdoms.

In the sense of modern phytogeography, Li's X. (1986) use of the Cathaysia

North American Subprovince implies that western North America territorially belonged or was connected to the Cathaysian terrane. However, in all Paleozoic geographic reconstructions. Western North America and Cathaysia are separated on

the eastern and western coasts of Pangaea. Therefore, North America cannot be a

Cathaysian subprovince due to its territorial discontinuity. It was named so by Li,

X. (1986) perhaps because of the distinct gigantopterids that existed on both continents, and both vegetation types have been called the Gigantopteris floras.

In order to clarify the above situation, following the example of Takhtajian's

(1986) classification, all Late Paleozoic floras, in this chapter, are briefly divided into

three phytogeographic kingdoms: the Angara, the Pan-Tropical, and the Gondwana, based on their latitudinal distribution and their generally unique plant assemblages.

The Pan-Tropical Kingdom includes three regions: Western North America, West

Paleo-Tethys, and Cathaysia (Table 16).

123 The Western North America Region includes four provinces: central Alaska, western Rocky Mountains, Texas, and Kansas. They are defined by the central

Alaska, Supia, Glenopteris, and Gigantopteris Floras, respectively. Considering their problematic affinities and small areas, putting them temporarily into Western North

America Region is still not a satisfying treatment.

The West Paleo-Tethys Region includes three provinces; 1) the Europe, 2)

Eastern North America, and 3) Spanish Provinces. The previous Euramerica flora is divided into the first two provinces. The Spain province refers to the southwestern

Paleo-Tethys and northern marginal region of Africa, where some mixed floras existed. Floras in this region are basically Euramerican in nature, although some mixed Cathaysian elements can be found in the Spain Province (see discussion later in this chapter).

The Cathaysian Region consists of three provinces: South China, North China, and Tarim-Qilianshan. Gigantopterids are characteristic of the former two provinces, but absent from the latter. These three Cathaysian provinces will be further discussed in this chapter.

This classification will not be further generally discussed, although it remains to be completed. This chapter will cover the following: the Gigantopterid Biome, the classification of the Cathaysia Region, the mixed floras around the Paleo-Tethys, and the reconstruction of the Paleo-Tethys. The possible migration pathway of gigantopterids between the Cathaysia Region and Texas will be also discussed, and

1 2 4 two new reconstructions of Permian paleogeography are presented based on megafossil plant data.

THE GIGANTOPTERID BIOME

In order to recognize the distinct gigantopterid vegetation present on the two remote continents, the Gigantopterid Biome is proposed as a non-systematic phytogeographical category. Based on the contemporary concept of biomes, a biome can include floras of a distinct type even if they are in disconnected areas, and can be named after the typical floral habitat, or habit, or plant type (Brown and

Doubinger, 1983). Therefore, the Gigantopterid Biome is proposed to include all floras which existed during the Permian and probably also the earliest Triassic period, and are characterized by gigantopterids and their associated plants. This

Gigantopterid Biome occupied most of the area of the Cathaysia flora and the western North American flora. Terminologically, the Gigantopterid Biome is modified from the previously named Gigantopteris Flora. The latter should not be used to refer the western North America flora, since gigantopterids found there have no real Gigantopteris at all.

Gigantopterids are the dominant plants in the Permian coal-bearing strata of the Cathaysian flora in Asia. Since Schenk’s (1883) incomplete description and illustrations, all gigantopterids found before 1936 were placed in the genus

Gigantopteris. Therefore, the coal-bearing strata have commonly been termed the

Gigantopteris Coal Measures, with the vegetation subsequently called the

Gigantopteris flora (Halle, 1927).

125 Halle (1935) recognized three Permian floras in Asia: 1) the Indian

Gondwana flora or Glossopteris flora, 2) the Angara flora (the Kusnezk flora), and

3) the Cathaysia (Sino-Malayan) flora or Gigantopteris flora. He adopted the term

"Cathaysia" from Graubau’s paleogeographic maps for the areas of eastern China and

Malaysia. He pointed out that the Cathaysia Flora was different from the

Gigantopteris flora, because the latter represented only the last phase of the

Paleozoic flora of Cathaysia, and it had been used also for the contemporaneous flora of western North America (Halle, 1935, P. 141). Therefore, both terms were not synonymous.

Gu and Zhi (1974) further defined the Cathaysia flora as characterized by gigantopterids, Tingia and some taxa with Mesozoic features, as well as some

Euramerican elements. They pointed out that from the Lower Carboniferous to the base of the Upper Carboniferous, the plant assemblages of the Cathaysia flora are similar to those of the Euramerican Flora. The Cathaysian T/ng/a and other endemic taxa did not occur until the Late Carboniferous, while gigantopterids {Cathaysiopteris and Gigantonoclea) occurred from the late Early Permian. Gu and Zhi (1974) recognized two Early and two Late Permian plant assemblages, and pointed out the floristic differences between southern and northern China Permian floras. Li, X. and

Yao (1979,1985) emphasized the floristic differences between southern and northern

China and established five plant assemblages for each (Table 10).

All previously reported gigantopterids have pinnate secondary veins arising from a single primary vein (midrib) and can be divided into three groups bearing C-,

126 G-, and E-type venation patterns (Chapter III; Table 8). In southeastern Asia, the

G-type Gigantonoclea is abundant both in number of species and individuals in South and North China provinces. The G-type Gigantopteris is generally limited to the

South China Province, with a few exceptions reported from the northern Anhui

Province (Gu and Zhi, 1974) and Yuxian, Henan Province (Yang, 1985, 1987). The

C-type Cathaysiopteridium and Zeilleropteris have been found only in the South China

Province, while the C-type Cathaysiopteris is reported only in the North China

Province (Table 11).

Although both C-type and G-type are now included in the gigantopterids, they may not be related, in the sense of origin. Morphologically, the C-type

Cathaysiopteris has been suggested to have originates from Callipteris tachingshanense, while the G-typeGigantonoclea was proposed to come from E. triangularis (Chapter

III). The same conclusion can be drawn from the stratigraphie occurrences of these taxa. In North China, C-types occur in the Yuxian flora, Henan Province, from the early Early Permian, but evolved parallel with the slightly later occurring G-type

(Yang, 1985, 1987). In South China, the C-type occurred later than Gigantonoclea and Gigantopteris in the Tongziyan (= Tongtzuyen) flora, Fujian Province.

According to Huang, L. et al. (1989), the Tongziyan Formation, 870 meters thick, is divided into 101 lithologie layers. Gigantonoclea occurred in 32 layers between layers

8 to 99, Gigantopteris in layers 54, 60, and 68, and Cathaysiopteridium in layers 68 and

85 (the layers lack Gigantonoclea). The three genera first appear respectively in layers 8, 54, and 68, with vertical intervals of 370 and 77 meters. The C-type

127 Cathaysiopteridium occurred after G. dictyophylloides and G. cordata and not

associated with Gigantonoclea. Therefore, the C-type and G-type are probably

unrelated groups in China.

The Gigantopteris floras in Texas and Oklahoma do not contain Gigantopteris,

but include six other gigantopterid taxa (Mamay, 1960, 1986, 1988, 1989; Mamay et

al, 1988; Table 12). Among these, Evolsonia texana and Delnortea abbottiae are two

endemic taxa. They do not have well preserved venation details, but both have

prominent secondaries (and tertiaries) in a "herringbone" pattern and thus can be

temporarily referred as E-type after Evolsonia (Chapter III). These taxa seem to be

more or less comparable with some Chinese gigantopterids, e.g., Neogigantopteridium

(Yang, 1987) and Gigantonoclea crassinevis (Liang, 1988). G. americanum is another

endemic taxon that has a forked midrib. Cathaysiopteris yochelsonii (Figs. 15-16)

appears to be endemic since it also has a forked midrib, although it is con-generic with Asian C. whitei (Figs. 7-8). Zeilleropteris wattii (Figs. 5-6) has more nets than

Chinese Z. yunnanensis (Fig. 9). These three taxa, G. americanum, C. yochelsonii,

and Zeilleropteris wattii, have similar C-type venation, resembling Asian C-types.

Gigantonoclea sp. is the only North American taxon that corresponds to the Asian

G-type. A recent re-examination of these specimens of Gigantonoclea sp. at the

Smithsonian Institution reveals that: 1) they have at least three orders of veins, with

the ultimate two orders being pinnate; 2) the ultimate veins give off about five pairs

of alternate vein lets which dichotomously divide and form simple meshes; 3) the veinlets form the companion meshes bilaterally along the ultimate veins, as well as

128 along the next lower order vein (Fig. 21). These features suggest they do belong to

Gigantonoclea. In Texas, G-type Gigantonoclea sp. and C-type G. americanum are

the earliest American gigantopterids, and both are from the Belle Plains formation

(Mamay, 1968, 1988).

Both North American and Asian Permian floras include Cathaysiopteris,

Zeilleropteris, and Gigantonoclea. Besides these gigantopterids, both floras also have

Riissellites (Mamay, 1968, 1995, Mamay et al., 1988). Asama (1976) treated these

similarities as a parallelism, while Mamay et al. (1988) considered that the two floras

were closely related, and that one was derived from the other. Mamay (1960), and

Mamay et al. (1988) suggested the Asian gigantopterids migrated from North

American.

The Leonardian Series of American Gigantopteris floras has been correlated with the Tongziyan Formation (the late Early Permian; Table 12), Fujian Province,

southern China by Li, X. and Yao (1983, P. 13). In China, both C-type

Cathaysiopteris (Yang, 1985, 1987; Table 12) and G-type Gigantonoclea borealia

(Huang, B.-H., 1986) have been found in the early Early Permian. These older

Asian gigantopterids obviously did not migrate from the younger American

Gigantopteris floras. Conversely, these older Chinese gigantopterids could have

migrated to North America by the Paleo-Tethys currents. Many mixed Cathaysia-

Gondwana or Cathaysia-Euramerica floras of Permo-Carboniferous age have been

found in the South and West Paleo-Tethys regions. Along with these mixed floras.

129 a potential migration pathway of gigantopterids can be traced from South and/or

North China Provinces to Texas. This will be discussed later in this chapter.

To underscore these similar disjunct floras, the Gigantopterid Biome has been established. This biome is characterized by gigantopterids and their associated endemic plants. To avoid confusion with the common term Gigantopteris flora,

Gigantopterid Biome was named not after Gigantopteris. Geographically, the

Gigantopterid Biome includes South and North China Provinces of the Cathaysian

Region and Texas Province of the Western North America Region. Chronologically, the biome ranges from the later part of the early Early Permian (Yao, 1983a;

Guyang and Li, 1980) to the end of the Permian, perhaps into the Early Triassic, the time range of the gigantopterids.

Although both the Cathaysia Region and the Gigantopterid Biome are phytogeographical categories, both are not synonymous in the sense of classification types. The former is a systematic hierarchy category and is limited to a continuous territory, while the latter is not a hierarchy category, but a category to distinguish different venation patterns based on habits or habitat. The Gigantopteris floras in

North America belong to the Gigantopterid Biome, but do not belong to the

Cathaysian Region. On the other hand, the Tarim-Qilianshan floras do not belong to the Gigantopterid Biome since there were no gigantopterids in this region. This is also the reason for separating the Tarim-Qilianshan flora from the North China

Province as the third Cathaysian Province, and leads to a new classification of the

Cathaysian floral region.

130 CLASSIFICATION OF THE CATHAYSIAN REGION

The Cathaysia Region, as a systematic term, is defined by the Cathaysia Flora, characteristically includes gigantopterids, emplectopterids, and other associated endemics. The time range of the Cathaysia Region extended from the Late

Carboniferous (Gu and Zhi, 1974; Li, X. and Yao, 1979, 1985), to the close of the

Permian, perhaps into the Early Triassic (Yao, 1983a; Ouyang and Li, 1980).

Geographically, the Cathaysia Region is divided into three provinces. South

China, North China, and Tarim-Qilianshan (Figs. 1, 200). The third is separated from the original Northern Subprovince. Gu and Zhi (1974) compared the floral differences between northern and southern China. Li, X. and Yao (1979, 1982,

1985) established the Northern and Southern Subprovinces, each with five plant assemblages (Table 10), based on both lithologie and paleobotanic characteristics.

The sediment sequences of the Late Paleozoic in northern China are predominately terrestrial, extending from the Middle Carboniferous to the top of Permian. In southern China, most areas were marine, although terrestrial sediments of the

Middle Devonian to the top of the Permian have been found at different localities.

The floras in China were Euramerican in composition until the introduction of some Cathaysian endemics in the Late Carboniferous. These include Tingia (more than nine species), Tingiostachys, Alethopteris (e.g., A. hallei, A . stmelenii, A. hiiiana),

C. tachingshanense, C. koraiense, Lepidodendron ocidus-felis, L. posthumii, L. szeianum, Cathaysiodendron incertum, C. nanpiaoense, and Bolhrodendron kuianum.

It is these plants that differentiated the Cathaysia Flora from the Euramerican. In

131 the early Early Permian, these taxa continued with the appearance of many

additional endemics, including Lobatamularia sinensis, E. triangularis,

Emplectopteridiumalatum, Taeniopteris spp., Tingia carbonia, Pecopterisorientalis, and

others (Gu and Zhi, 1974; Li, X. and Yao, 1985).

Cathaysiopteris whitei was originally described from the late Early Permian (the

third northern assemblages of Li, X. and Yao, 1985), but has now been reported from the early Early Permian in northern China (Fig. 201; Yang, 1985, 1987). It has

not been discovered in southern China which has other C-type plants, such as Z. yunnanensis (= Zeiller’s Gigantopteris nicotianaefolia) in Yunnan Province and C. fasciculatum in Fujian Province (Huang, L. et al., 1988). Gigantonoclea exhibits sim­

ple mesh venation and a few species, such as G. lagrelii and G. hallei, are known

from both floral provinces. Most species, however, are limited to a single province.

For example, G. lobata, G. rosulata, G. mira, G. kaipingensis, and G. taiyuanensis are

limited to northern China, while G. guizhouensis, G. fukienensis, and G. acuminatiloba

are restricted to the South China province (Gu and Zhi, 1974; Li, X. and Yao, 1985).

Gigantopteris, characterized by compound reticulate venation, is usually found only

in the South China Province. However, a few exceptions have been noted from

southern Henan and northern Anhui Provinces, northern China (Fig. 201; Yang,

1985, 1987; Gu and Zhi, 1974).

In addition to the gigantopterids, other Permian floral elements differ between

the two provinces. For example, in North China, Emplectopteris spp. are abundant

in the Lower Permian, and Taeniopteris spp. occur in the Upper Permian. In South

132 China, these taxa are rare, butDanaeites and Otofolium are common (Gu and Zhi,

1974). During the Late Permian - Early Triassic, the North China Province became more arid, while South China remained a tropical rain-forest flora (Wang, Z., 1985).

The floristic affinities of the Qilianshan region in northwestern China have been debated, since some Cathaysian endemics, Angara elements, and Euramerica plants have been found there in the Late Permian. Halle (1937b) concluded that the

Angara flora overlapped the Cathaysia flora at the site of the Nanshan flora (=

Bexell’s flora) in the Qilianshan region. Li, X. and Yao (1985), and Li, X. (1986) plotted this area as part of the Northern Subprovince. Wang, D. et al. (1984,1986) suggested separating this region from the Northern Subprovince as a third floral type within the Cathaysia Province. Wang, Z. (1985) suggested that the Late Permian and the Early Triassic portion of this region, along with Western European floras, should be incorporated into the Eurasian Arid Province. Others (e.g., Durante, 1983,1992;

Don and Sun, 1985; Sun, F., 1989) considered this area to be Sub-Angaran. Since the Permian Tarim flora has been reported to be similar to the Qilianshan flora (Hu,

Y.-F., 1990; Wu, 1983; Wang, D. et al., 1984; Dou and Sun, 1985; Sun, F., 1987), the two areas are considered together as the Tarim-Qilianshan Province or Flora in this dissertation.

1. North China Province

The North China Province includes Korea, Japan, the southern part of

Northeastern China, and northern China (southern Nei Mongol, Hebei, Shaanxi,

Shanxi, northern Henan, Shandong Provinces; Figs. 1 and 200). The majority of the

133 landmass occupied by the North China Province was formed during the Precambrian, including the oldest rocks (3.4 billion years ago) in Hebei Province. This floral province is basically an epeiric sea region. On the east side, the lowest Late

Paleozoic sediments belong to the Benxi Formation in southern northeastern China.

This formation has coal-bearing sequences and has been found directly overlapping

Middle Ordovician limestone. Toward the south and west, the overlapping strata were deposited gradually later, so that there was very little Middle Carboniferous deposited in Taiyuan, Shanxi and Huainan, Anhui. This indicates the transgression started from the northeast toward the southwest. The Benxi flora was similar to the

Euramerican Flora, but many Cathaysian endemic elements occurred since the Late

Carboniferous (the Taiyuan formation). Later, the Permian Gigantopteris flora developed (Editorial Group of "Geography of China," 1986; Gu and Zhi, 1974;

Table 13).

The nature of North China can be represented by the Taiyuan flora of Shanxi

Province (Halle, 1927). The Permian Gigantopteris flora has Cathaysiopteris and many species of Gigantonoclea, but lacks Gigantopteris and Cathaysiopteridium. In addition to gigantopterids, Emplectopteris is abundant in the Lower Permian and Taeniopteris in the Upper Permian (Table 13).

In the south marginal region of the North Province, Yang (1985, 1987) reported a mixed South-North flora from Yuxian County, southern Henan Province.

She found that the flora has not only many species of Gigantonoclea and

Cathaysiopteris, but also Gigantopteris, and several other gigantopterid taxa. Her first

134 two assemblages (Upper Carboniferous - Lower Permian) include North China floral elements, but her third and fourth (upper Lower Permian-lower Upper Permian) include mixed floral elements of both South and North Provinces. For example,

Yang’s third assemblage has the following taxa that are similar to the South China flora: Cladophlebis ozakii, Sphenophyllum sino-koreaniim, Pecopteris anderssonii,

Compsopteris ellipticus, C. contracta, Neiiropteridium coreanicum, and Gigantopteris.

Gigantopterids, pecopterids, Sphenophyllum, and cordaites are dominant. Mean­ while, this assemblage has the following taxa in common with the North China Prov­ ince assemblages: Annularia gracilescens, Gigantonoclea unita, G. yiaianensis, G. tieyingensis, Fascipteris kaishantunensis, Taeniopteris integra, and Pecopteris sp. (Yang,

1985, 1987; Fig. 201).

Recently, Mei et al. (1996) suggested the northern Jiangsu, northern Anhui, and southern Henan Provinces be included in a triangular Xu-Huai-Yu region as a new subprovince of the Cathaysian Province. It is my opinion that this region should be retained in the North China Province based on the following: tectonically, it is bordered by two tectonic structures, the Kunlun-Qinling syncline to the south and the Tanlu Fault to the east (Editorial Group of "Geography of China," 1986; Mei et al., 1996). However, this region has never been considered an isolated block or structural landmass from the North China Block (Editorial Group of "Geographic

Atlas of China," 1984; Yin and Nie, 1993). Sedimentologically, this region belongs to the southern part of the Late Paleozoic Northern China Basin. When compared with the northern part of the basin, both have the Middle Carboniferous

135 unconformably overlying on the Middle Ordovician. Both regions have similar facies except there is less Middle Carboniferous deposited at Huainan, Anhui (only 4 meters) in the southern than in the northern part (50-70 meters). These facies of

Northern China are usually called “Northern Facies.”

Mei et al. (1996) proposed the Xu-Huai-Yu Subprovince because sediments of the exhibit in a “Southern Pattern,” although they are characteristic of “Northern

Facies.” So-called “Southern Pattern” mainly refers to the coal-forming ages in

South China Province. In southern China, coal seams formed from the Early

Permian in the east region (e.g., southern Jiangsu, Zhejiang, Jiangxi, and Fujian

Provinces), to Late Permian in the west area (e.g., Sichuan, Guizhou, and Yunnan

Provinces). In the North China, coal-forming periods of the northern region are from the Late Carboniferous to the late Early Permian (Editorial Group of

"Geography of China," 1986). In the Xu-Huai-Yu region, the coal-forming periods in Huainan extend from the early Early Permian to the early Upper Permian, later than those in northern region. Since the coal-forming periods in Xu-Huai-Yu are coeval with those in South China, the sediments are described as in “Southern

Pattern.” However, the “Southern Pattern” is commonly interpreted as a result of the transgression of an epeiric sea in North China Province, that started from the northern toward the southern so that the coal-forming periods were postponed in

Huainan region. However, this “Southern Pattern” should not be used as a key character to separate the Xu-Huai-Yu region from the North China Province.

136 Floristically, the Huaibei flora is just an Early Permian flora with the northern

elements C. whitei and many Lobatanniilaria spp. The Huainan flora (Fang, 1986)

has four plant assemblages that are generally similar to those of North China. The

southern Gigantopteris has been reported from Mengcheng, northern Anhui (Gu and

Zhi, 1974) and the late Early Permian in Yuxian County, Henan (Yang, 1985,1987).

Therefore, this region basically belongs to the North China Province. The

appearance of Gigantopteris may be treated as a signal of the accretion of the South

China Block (SCB) to the North China Block (NCB) (Yin and Nie, 1993), but not

as a factor separating the region from North China. Therefore, the Xu-Huai-Yu

region should be retained in the North China Province (Fig. 200; see further

discussion in this dissertation).

2. Tarlm-Qiiianshan Province

The northwest area in the Northern subprovince is the Qilianshan region, which has no gigantopterids reported, although many other Cathaysian elements have

been found there. Some similar floras were reported from the Tarim (= Talimu)

region, which was included in the Angara flora region (Li, X. and Yao, 1985).

Wang, D. et al., (1984,1986) suggested that the Qilianshan region be separated from

the Northern Subprovince and incorporated with the Tarim region into a third

Cathaysian subprovince.

The Tarim-Qilianshan Province is separated from the North China Province

by the north-south trending Helanshan-Liupanshan Mountains. This Province consists of two regions, Tarim and Qilianshan. The Qilianshan region has been a

137 source of controversy since Bexell collected some specimens from Nanshan, Gansu,

during a 1927-1933 expedition. These collections were divided into four plant-bear­

ing zones by Bexell. Halle (1935, 1937b) inspected some of Bexell’s collection and

found that, although Zones A and B were Cathaysian, Zone C was composed of

Angaran plants; including Phyllotheca deliquescens, P. cf. schtschiirowskii, Callipteris

sp. (aff. C. zeilleri), C.? murensis, Iniopteris sibirica, Brongiartites salicifoUus, Zamio- pteris glossopteroides, Rhipidopteris ginkgoides, R. lobata, and Noeggerathiopsis scalprata. Halle concluded that the Angara flora overlapped the Cathaysia Flora

(Halle, 1935, 1937b).

Li, X. and Yao (1982) pointed out that in the Nanshan Section, the Angara

flora does not overlap the Cathaysia Flora, but is contemporaneous with it during the

Late Permian. In other words, the Angaran plants are mixed with many typical

Cathaysian elements that are found in the Upper Shihhotse Formation in northern

China {Lobatannularia lingulata, Pecopteris anderssonii, and Rhipidopsis lobata, etc.)

Durante (1983, 1992) subsequently reinvestigated more than 300 specimens of

Bexell’s collection from Zone C and reported a list of 55 taxa. Among these, typical

Cathaysian elements are rare, including only Pecopteris cf. anderssonii and fragments

of leaves with reticulate venation. Durante concluded that the flora was Angaran, and the mixture of Cathaysian elements was insignificant.

Wang, D. et al. (1984, 1986) reinvestigated the Nanshan flora, but their studies are not well known in the west. They followed Bexell’s route and relocated the Nanshan flora with the assistance of Mr. Jingyi Hao, who had worked as a porter

138 for Bexell. They discovered that the Nanshan section described by Bexell is not a

single stratigraphie section, but a generalized profile of the region. The profile ex­

tends from the Upper Carboniferous to the Middle Jurassic, with the lower three

Bexell zones (A, B, and C) belonging to the upper Paleozoic. They collected a large

number of fossil plants and reclassified the Permian strata and their different floral

elements (Table 14).

During the Late Carboniferous and early Early Permian, Euramerican elements were dominant 28 species, comprising 62% of the Tongwei assemblage, lower l,ower Permian). However, the flora was dominated by

Cathaysian elements during the late Early Permian and early Late Permian. For example, in the Dahuanggou assemblage (upper Lower Permian), Cathaysian elements represent about 62%, while Euramerican elements comprise only about

30%.

By the late Late Permian (the Jiayuguan Formation = Bexell’s Zone C), the flora changed to a mixed Angaran-Cathaysian (64% Angaran elements and 36%

Cathaysian taxa), with a total of 39 taxa (Wang, D. et al., 1986). The major

Cathaysian elements are: Lobatannularia heianensis, L. cf. lingulata, Compsopteris wongii, C. imparls, Taeniopteris taiyuanensis, T. schenkii, Tingia?yanlunensis, Pecopteris tenuicostata, P. gracilenta, Rhipidopsis ginkgoides, Alethopteris sp., Pterophyllum sp., and Ctenozamites sp. There is only one Euramerican element, Albertia sp. In another report (Wang, D. et al., 1984), 65 species of 34 genera are listed from Zone C of the generalized profile in the region. Among these 65 species, 58% (20 genera, 38 spe-

139 des) belong to Angaran types, 35% (13 genera, 23 species) are Cathaysian, and only a few Euramerican elements, including Amalepis, Albertia, Voltzia, and Lebachia.

These Euramerican taxa are often found in the Lower Triassic of Western Europe.

It should also be mentioned that gigantopterids have never been reported in this region. Zhang and Shen (1987), and Shen and Zhang (1987) reported similar findings. Thus, the flora of Zone C should be interpreted as a mixed flora rather than an Angaran flora as Halle (1937b) and Durante (1983, 1992) concluded. As

Wang, D. et al. (1986) noted, previous Angaran interpretations by other authors might be due to insufficient collections.

The Tarim region is another interesting area that lies in the south Xinjiang

Autonomous Region. The late Early Permian - early Late Permian flora of the region is similar to the coeval Nanshan flora. Both lack gigantopterids, but share some common Cathaysian elements, such as Tingia, Lobatannularia, and

Emplectopteris, although their numbers are fewer than in the area east of Helanshan-

Liupanshan Mountains. Similarly, by the late Late Permian, this area contained a mixed flora, with both Cathaysian elements (e.g., Schizoneura manchuriensis) and a few Angaran elements {e.g., Comia, Callipteris zeilleri, C. altaica\ Wu, 1983). In

Jungar and Turpan of northern Xinjiang (Figs. 1 and 200), Permian floras are

Angaran with very few Cathaysian elements (Hu, Y.-F., 1990; Wu, 1983; Wang, D. et al, 1984; Don and Sun, 1985; Sun, F., 1987, 1989).

In summary, the Tarim-Qilianshan region has the following features: 1) The dominant floral elements in the Nanshan flora changed from Euramerican to

140 Cathaysian, and finally to Angaran, from the Upper Carboniferous to the Upper

Permian. 2) Considering the Cathaysian South and North China floras were

differentiated from the Euramerican flora and also contain many Euramerican

elements, the Nanshan flora of the Early Permian and the early Late Permian, with

36%-86% Cathaysian elements, should be considered Cathaysian in nature. Only in the late Late Permian did the flora change into mixed Cathaysian-Angaran. 3)

Compared with the Cathaysian South and North China provinces, the Tarim-

Qilianshan region has few taxa of Lobatannularia, rare Lepidodendrales and Fascipte- ris, but more Tin^a and Yiiania. 4) No gigantopterids have been reported from the region west of the Helanshan-Liupanshan mountains. The combination of these features make the region a unique Cathaysian to mixed Cathaysian-Angaran flora.

For this reason, a Tarim-Qilianshan Province is foimally established under the

Cathaysia Region in this dissertation. This agrees with the proposal of Wang, D. et al. (1986), that the Tarim-Qilianshan flora should be separated from North China as a separate subprovince of the Cathaysia Flora.

3. South China Province

Any connection between the Gondwana continent and the south China

Province is unknown, though some mixed floras have been reported from Tibet and the sutural line is roughly considered to be along the Lancangjian River (= Mekong

River) in Yunnan, China, and the Nam-Ou River in Laos, stretching south to

Sumatra. The region located west of this line is called the Sibumasu Block (Nie et a l, 1990, 1993) and belongs to the Glossopteris flora (Li, X and Wu, 1994). East of

141 this line is Indochina where the Permian gigantopterids are not present. Recently,

some gigantopterids have been found from A-Du-Di, Zhong-Pai-Xiang District, Lan-

Ping County, Yunnan, west of the Lancang River, including G. nicotianaefolia, G. guizhouensis, and other Cathaysian elements (Li, D., 1990). This may indicate the sutural line should be plotted west beyond the Mekong River. The South China

Province consists of three major blocks: southern China (SCB or Yangtze Block),

Indochina, and North Tibet (= East Qiangtang; Nie et al., 1990; Sun, D.-L., 1993).

Southern China - This region contains several smaller blocks which underwent differing tectonic development. During the Late Paleozoic, marine, terrestrial, and marine-terrestrial interbedded sediments were deposited in different contemporary areas. As a result, there are at least two sets of stratigraphie classifications (marine and terrestrial), in addition to several local systems. During the Permian, a series of coal-bearing sedimentary sequences developed throughout southern China. This series was originally called the Longtan Formation, or “Gigantopteris Coal Series” since the series contains numerous gigantopterid taxa. However, it has been recognized that, from east to west, the coal-forming periods vary from the late Early

Permian to the end of Permian (Yao, 1978). Some elements of the Gigantopteris

Flora, such as Gigantopteris, Pecopteris, Lobatannularia may have survived into the

Early Triassic as relics in Tibet.

Indochina — The Permian floras in this region appear quite similar to those of the South China Block. Many gigantopterids and their associated plants have been reported from several regions, including the area around the Nam-Ou River of

142 Laos (Vozenin-Serra, 1979), Loei of Thailand (Asama et al., 1968), Jengka Pass of

Malaysia (Kon’no and Asama, 1970), the Linggiu flora of Malaysia (Kon’no et al.,

1970), and Djambi of Sumatra (Jongmans and Gothan, 1935). Bicoemplectopteris hallei from Laos (Vozenin-Serra, 1979) appears similar to Gigantonoclea hallei and

G. guizhouensis. Tricoemplectopteris taiyuanensis reported from the Linggiu flora may be a species of Gigantopteris, since the compound mesh venation is distinctive based on Kon’no et al. (1970).

Abundant Euramerican and Cathaysian elements were reported from the

Sumatra flora (Jongmans and Gothan, 1925, 1934, 1935; Jongmans, 1935). The stratigraphie position was correlated with the Upper Carboniferous. Two gigantopterid species, Gigantopteris menkarangensis and G. bosschana (renamed as

Palaeogoniopteris menkarangensis and Gothanopteris bosschana by Koidzumi, 1936), were found there (Table 1), and the vegetation was assigned to the Gigantopteris flo­ ra. Since no Gigantonoclea has been found there, this flora may represent a very early stage of the Gigantopteris flora, although it was later compared to the Shanxi

Formation (Artinskian), Lower Permian (Asama et al., 1975).

North Tibet - Three east-west oriented floristic zones have been reported from

Tibet (= Xizang). The north zone has Late Permian Gigantopteris floras, including the Toba flora in the east (Li, X. et al., 1982a) and the Shuanghu flora in the west

(Li, X. et al., 1982b). Thirty-six species have been described from the Toba flora, representing pure Gigantopteris floral elements, such as, Lepidodendron oculus-felis,

Sphenophyllum, Lobatannularia, Schizoneura manchuriensis, Rajahia, Pecopteris

143 anderssonii, Fascipteris, Rhipidopsis pani, Gigantonoclea spp. and Gigantopteris dictyophylloides. The Shuanghu flora has similar elements, but fewer taxa (17 species) than the Toba flora.

SOME MIXED FLORAS IN THE SOUTH PALEO-TETHYS

Kon’no (1966) first pointed out the close relationship between the Cathaysia and Gondwana continents based on shared taxa, such as Schizoneura and Rhipidopsis.

According to Scotese and McKerrow (1990), all Cathaysian microcontinents in the south Paleo-Tethys were attached to Gondwana before they started to move away at different rates beginning in the Devonian. It is possible for some microcontinents to carry Gondwana elements to Cathaysia and to result in mixed floras. Some mixed

Gondwana-Cathaysia floras have been found between the two kingdoms (Li, X.,

1986), such as those reported from New Guinea, Xiagangjiang (Middle Tibet), South

Tibet, Kashmir, and Turkey.

New Guinea - On Scotese and McKerrow’s (1990) Permian maps, this flora is geographically close to the Jengka Pass and Linggiu floras, and contains some

Cathaysian plants, such as Sphenophyllum verticillatum, Pecopteris, and Taeniopteris associated with the typical Gondwana taxon Vertebraria (Jongmans, 1940). Recently, some specimens from New Guinea have been identified as Gigantonoclea sp. and

Fascipteris sp. (Li, X., 1986; Li, X., and Wu, 1994), and this suggests that the flora is a typical mixed Gondwana-Cathaysia type developed on the northeast edge of

Gondwana.

144 Middle Tibet (West Qiangtang) - A mixed flora, reported from Xiagangjiang,

Gerze (Li, X. et al., 1985), has 17 species, but most are Gondwana types (e.g.,

Phyllotheca, ISchizoneura sp. [of. S. gondwanensis Feistm.], Noeggerathiopsis hislopii,

N. spp.) with a few Cathaysian elements present (eg., Pecopteris aff. arcuata,

Plagiozamites oblon^foliiis). This flora, perhaps belonging to the late Early Permian,

lacks both typical Gondwana elements, such as Glossopteris and Gangamopteris, and

Cathaysian taxa, such as Gigantopteris and Gigantonoclea. Whether this is an artifact

based on collections is not known.

South Tibet - Hsii (1976) reported a pure Glossopteris flora (seven species)

from the Qiibu Formation, Early Permian, Dingri and Dingjie districts. He

suggested there was no relationship between Gondwana and Cathaysian floras.

However, one species, Raniganjia qubuensis, was later referred to the Cathaysian

taxon Lobatannularia by Singh et al. (1982). Subsequently the Qiibu flora was

thought by Li, X. et al. (1985) to represent a mixed Gondwana-Cathaysian flora

similar to the Xiagangjiang flora of middle Tibet and the Mamal flora in Kashmir

(Singh et al, 1982). Hsii et al. (1990) reviewed Hsü’s (1976) study and suggested

thati?.qubuensis should h t Austroannularia qubuensis. They believe that most plants

in their new list (Table 15) are Gondwana types, such as Glossopteris spp.; however,

they accept that a few Cathaysian elements, such asSphenophyllum minor and

Pecopteris cf. unita, existed there, also. Thus, they seem to support the concept of

a mixed flora.

145 Kashmir -- Singh et al. (1982) reported on the Late Paleozoic flora of this

region which ranged in age from Upper Devonian to Permian. The upper Lower

Permian Mamal Formation contains Glossopteris floral elements plus two Cathaysian

taxa, Lobatannularia ensifolia and Rajahia mamalensis^ thus making the Mamal flora

a mixed Gondwana-Cathaysia type.

Turkey - The Carboniferous flora, fauna, and lithostratigraphy of Turkey show

strong links with the Euramerican realm (Kerey et al., 1986). However, the Permian

flora is a mixed Gondwana-Cathaysian type. Wagner (1962) reported G.

nicotianaefolia associated with Glossopteris cf. stricta (renamed as G. anatolica by

Archangelsky and Wagner, 1983) and Pecopteris nitida from the Hazro flora, Turkey.

On some specimens, gigantopterid leaves can be seen preserved together with

Lobatanntdaria heianensis or with Pecopteris cf. wongii. The age of the flora was

thought by Wagner (1962) to be the earlier part of the Permian, but it was later

revised to uppermost Permian by Archangelsky and Wagner (1983). These

specimens of G. nicotianaefolia were renamed as G. hallei (Kon’no et al., 1970;

Kon’no and Asama, 1970), but later Li, X. et al. (1982b) suggested they represented

Gigantonoclea cf. guizhouensis. The specimens did not show venation, leaf shape, or

margin very clearly so that they can not be identified with confidence, but the vena­

tion looks similar to some Gigantonoclea specimens from southern China. This im­

plies a closer phytogeographic relationship between Turkey and southern China,

than with northern China.

146 SOME MIXED FLORAS IN THE WEST PALEO-TETHYS

In the western Paleo-Tethys, the Permian floras reported from Saudi Arabia

and Spain show a mixed floral nature different from those in the above Gondwana-

Cathaysia floras. These floras are basically Cathaysian-Euramerican in nature, and

for this reason, are included in the West Paleo-Tethys Province. There may be more

such floras that have not been recognized from this province, especially on the

northern margin of Africa.

Saudi Arabia - El-Khayal et al. (1980) reported an assemblage of plants from

the Permo-Carboniferous of Unayzah, Saudi Arabia and suggested it had affinities with the Euramerican flora. Lemoigne (1981a, 1981b) reclassified the flora as a

mixed Euramerican-Cathaysian one, since some Cathaysian elements were found

there, including Lobatannularia cf. heianensis, Fascipteris hallei, Pecopteris cf. wongii,

and Cladophlebis aff. roylei. He thought the flora was similar to the Hazro flora in

Turkey. El-Khayal and Wagner (1985) accepted Lemoigne’s assemblage, but added

some Cathaysian elements, even some rare specimens of Gigantonoclea sp., into the

assemblage. They suggested that the age of the flora was early Late Permian. This

is a mixed Euramerican-Cathaysian flora without any Gondwana elements, with the

nearest Glossopteris flora (Permo-Carboniferous) reported from Entebbe, Uganda,

3,000 km south from Turkey (El-Khayal et al., 1980).

Spain - A mixed flora was described from Guadalcanal which consists of

Cathaysian elements (eg., Lobatannularia, Problechnum cf. wongii, Psygmophyllum cf. miiltipartitum, Fascipteris robusta), Euramerican elements (e.g., Annularia spp.),

147 Angaran elements {e.g., KoretrophyUites crassinervis and Entsovia sp.), and some

Gondwana elements {e.g., Gingkophytopsis sp. and G. kidstonv, Broutin, 1982; Broutin and Doubinger, 1983). Some plants, such as Rhipidopsis baetica, Ginkgoites, and

Koretrophyllites-Phyllotheca, can be seen in the Permian of Angara, Cathaysia, and

Gondwana. Thus the flora seems to contain elements from four regions. According to Lemoigne’s (1981a, 1981b) maps, Spain was traditionally placed in the

Euramerican Flora, but the number of different floral representatives found there makes the region puzzling. There are no typical Gondwana plants, or Angaran plants like Zamiopteris, but Cathaysian elements, such as Lobatannularia,

Problechnum, and Fascipteris, are present. Furthermore, there are no gigantopterids.

However, it should be kept in mind that Gigantonoclea in Saudi Arabia is very rare, and there are no records of C-type gigantopterids reported from Turkey to Spain.

RECONSTRUCTION OF THE PALEO-TETHYS

The Cathaysia Region was located in the vicinity of the Paleo-Tethys Sea.

Many structural reconstructions of the Paleo-Tethys have been made based on paleomagnetic data, but the relative positions of the blocks of China and southeast

Asia are still problematic. Most paleogeographic reconstructions place the South

China Block (SCB = Yangtze Block) in an equatorial latitude during the Permian, however, the longitudinal position is uncertain. Some people (Lin et al., 1985;

Chaloner and Creber, 1988; Scotese and McKerrow, 1990) reconstruct it in the eastern Paleo-Tethys. Scotese and McKerrow (1990) attach the SCB to the North

China Block (NCB) in the vicinity of Korea during the Late Permian. Others

148 (McElhinny et al., 1981; Nie et al, 1990; Sun, D.-L., 1993) place it in the western

Paleo-Tethys, and separate it from North China by the Qinling ocean. Similarly, the

Tarim-Qilianshan Block is plotted in different locations and adjacent to different blocks. With a review of these reconstructions and some paleobotanical studies, new reconstructions of the Paleo-Tethys are presented in Figs. 201 and 202.

1. The South Paleo-Tethys Area

This area was occupied by the South China Province and included some mixed floras. The South China Block includes the large-leafed Gigantopteris flora which is probably equatorial. Other microcontinents of this province would be in the south

Paleo-Tethys area. Several mixed floras were located at the south and southwest margin areas of the Paleo-Tethys. The gigantopterids reported from Indochina are very similar to those of the Yangtze Block, suggesting that the two areas might be adjacent as mapped by Scotese and McKerrow (1990).

The Sibumasu Block is adapted from Nie et al. (1990), and is equivalent to the western part of the Shan Tai-Malaya block. Since the latter included both

Glossopteris and Gigantopteris floras, it has not been used here. The Sibumasu Block, with exclusively Glossopteris floras, may have drifted from Gondwana, and thus, it is placed between Indochina and Australia. The mixed Gigantopteris-Glossopteris flora in New Guinea suggests that this area was at the south edge of the Paleo-Tethys, possibly near Australia.

The Tibet region is the least understood. Nie et al. (1990), Scotese and

McKerrow (1990), and Sun, D.-L. (1993) reconstruct the region quite differently.

149 Considering the floras, it is believed that northern Tibet should be close to the

Yangtze Block, since both have some common gigantopterids, e.g., G. guizhouensis.

Southern Tibet should be closer to India on the Sibumasu Block because of shared

Glossopteris. Turkey is placed between northern and southern Tibet because it contains Glossopteris and some gigantopterid plants similar to G. guizhotiensis.

Considering the Euramerican Carboniferous flora in Turkey, this block should be closer to Yangtze or northern Tibet. Middle Tibet also contains a mixed Gondwana-

Cathaysia Flora, but without typical elements of the two floras, e.g., Glossopteris,

Gangamopteris, Gigantopteris, or Gigantonoclea. For this reason, it is suggested that

Middle Tibet might have been between Turkey and Saudi Arabia. Saudi Arabia is a mixed Euramerican-Cathaysia Flora without Glossopteris species. All these blocks appear to have moved generally from southwest to northeast during the Permian

(Figs. 201 and 202).

2. The Collision between SCB and NCB

Li, X. and Yao (1985) have suggested that the Kunlun-Qinling geosyncline, which was the Qinling Ocean during the late Paleozoic, served as a natural barrier between the SCB and NCB. The estimates of the age of collision between the two blocks based on the geological data vary from the middle Paleozoic to the end of

Paleozoic, and may even have extended into the Early Mesozoic. Lin et al. (1985) suggest that the two blocks collided by Middle Jurassic time, while Scotese and

McKerrow (1990) predict that the ocean closed during the Late Triassic. Laveine et al. (1987, 1989) emphasize similarities in the five sets of plant assemblages

150 between the South and North provinces (Table 10). They argue that so many com­ mon taxa suggest the two blocks coalesced as early as the Lower Carboniferous.

They suggest that all other explanations for floral similarities, including winds, marine currents, and land bridges, are not acceptable when dealing with such a large assemblage. They agree with Mattauer et al. (1985) that the accretion between the two blocks occurred in the Devonian, and reconstruct Shan Thai-Malaya, Indochina, the South China Block (SCB), and the NCB as connected (Laveine et al., 1992). Nie et al. (1990) also recognized that a land connection between the North and South

China Blocks might exist so that both blocks have the same seed plants. Yin and

Nie (1993) suggested that the collision of the two blocks, starting from east to west, was accomplished by the indentation of the northeastern part of SCB into the southeastern part of NCB (Figs. 1 and 200). This collision began in the latest Early

Permian and lasted to the Late Triassic, or possibly Early Jurassic.

The history of the south-north mixed flora in the Xu-Huai-Yu Province can also assist in determining the accretion of the blocks. The northern endemic C. whitei has been reported from the Lower Permian Yuxian (Yang, 1985, 1987),

Huainan (Fang, 1986), and Huaibei floras (Mei et al., 1996). The southern endemic

Gigantopteris did not appear until the late Early Permian in Yuxian (Yang, 1985,

1987; Table 12; Fig. 201). Perhaps Gigantopteris was carried there from South China by the northward drifting SCB. If so, then the late Early Permian, the age of the third assemblage, is the time of collision. This result is consistent with the collision between the two blocks estimated by Yin and Nie (1993) (Fig. 200).

151 3. The Reconstruction of the North Paleo-Tethys

Scotese and McKerrow (1990) include Tarim and Sino-Korea together, but some distance from Western Europe during the entire Late Paleozoic. This is consistent with Li, X. and Yao’s (1979, 1985) model of the Northern Subprovince as consisting of Qilianshan and Sino-Korea blocks. In Scotese and McKerrow’s (1990) reconstruction, Tarim is plotted on the northern end of North China. It had collided with the southern Kazakhstan Block during the Late Devonian, then separated and drifted northeastward to a position between the Kazakhstan Block and the Siberian shield by the end of the Permian. Thus, the North China Province was closer to

Siberia than Europe during the Late Paleozoic. This reconstruction, however, is dubious based on the similarity between the North China and Euramerica floras prior to the Late Carboniferous, and the apparently contiguous communication between these two floras after that time.

The interpretation of the Nanshan flora of Wang, D. et al. (1984, 1986) is critical in the paleophytogeographic reconstruction of this region. The dominant floral types changed from the Early to the Late Permian (Table 14), suggesting that the block might have been a bridge between North China and Western Europe, eventually separating from Europe, and finally accreting to the Kazakhstan Block.

The early Early Permian Nanshan flora with 35% Cathaysian elements (Table 14) suggests that the block might have broken from Western Europe earlier (possibly the

Late Carboniferous) so that these Cathaysian elements could not immigrate into

Western Europe. Then, the Cathaysian elements dominated the flora until the late

152 Late Permian when the block accreted to the Kazakhstan Block. A few Angaran elements were found mixed in the Dahuanggou (= Bexell’s plant-bearing zone B) and Yaogou formations (Wang, D. et al., 1984,1986). This suggests that, beginning in the Visean, the Tarim-Qilianshan region drifted close enough to Angara land to allow a few Angaran elements to migrate there (Figs. 201 and 202).

By the time of the Xidagou Formation (Late Permian), this northeast drifting brought the region into an arid and colder climate. From the late Early Permian to the early Late Permian, the Nanshan area might have been Cathaysian in nature, but perhaps at a higher paleolatitude, so that there were fewer examples of

Lobatannularia and Annularia than that found in the North China Province. The climate might have been arid or semiarid so that the rare Lepidodendrales and

Fascipteris were present, but no large-leafed gigantopterids were able to survive.

Lin et al. (1985) considered that the accretion of the NCB to the Siberian

Block occurred in the Late Permian. This suggestion, however, is in conflict with the floral data. Huang, B.-H. (1977, 1983, 1986) and Huang, B.-H. and Gu, 1987 investigated Permian floras in Mongolia and northeastern China, and found that

Angaran elements did not appear in the Early Permian south of Linxi, Xianghuangqi, and Chaogeqi. There are only Cathaysian elements present, such as Emplectopteris minima, Pecopteris anderssonii, F. tenuicostata, F. arcuata, Annularia gracilescens, A . mucronata, Sphenopteris grabaui, Taeniopteris norinii, T. angustifolia, and even

Gigantonoclea borealia, that were present. The Late Permian also consists of

Cathaysian elements (Huang, B.-H., 1986). On the northern Nei Mongol side {eg.,

153 in the Linxi Formation) most Permian plants were Angaran. Only a few Cathaysian

elements, such as Lobatannularia multifolia and Schizoneura manchuriensis were

found, and these occurred only in the Late Permian. This suggests that the accretion

of the NCB to the Siberian Block had not occurred by the Late Permian time. The

few Cathaysian elements might not have migrated from the south, but rather from

the west, from Turpan or Jungar (northern Xinjiang). In this region the Angaran

Permian flora also occurred with a few Cathaysian elements, but earlier than in

northern Nei Mongol (Hu, Y.-F., 1990; Wu, 1983; Wang, D. et al., 1984; Dou and

Sun, 1985). This floristic difference between southern and northern Nei Mongolia

suggests that by the end of the Permian, most areas of the Nei Mongolia sea could

not have been fully closed, and the Nei Mongolian arcs perhaps did not exist. Thus,

the conclusion of Nie et al. (1990) that the Sino-Korea block joined the Nei Mongo­

lia Arcs in the Late Permian is questionable based on floral distributions.

An arid or semiarid environment in this area was recognized and emphasized by Wang, Z. (1985), who suggested referring the eastern-most part of the

Euramerican Province, Western Europe and North China (including the Tarim-

Qilianshan region), as "the Eurasian Arid Province". According to Wang, D. et al.

(1986), the Late Permian Nanshan flora is a mixed Angaran-Cathaysian flora with very few Euramerican elements. This suggests that the Tarim-Qilianshan region

should be closer to the Angara flora than to the Euramerica flora in the late Late

Permian.

154 CONCLUSION

Two sets of Permian phytogeographical classification are proposed in the above. Gigantopterid Biome is established as a non-systematic hierarchy category, and covers all Permian (maybe also the earliest Triassic) floras which are dominated by gigantopterids. It includes the western North America flora and both the south and the north China floras of the Permian. An incomplete, global phytogeographical classification of the Permian is also proposed, which divides the Permian vegetation into the Angara, Gondwana, and Pan-Tropical Kingdoms, with emphasizing on the latter. The Pan-Tropical Kingdom consists of the Western North America, West

Paleo-Tethys, and Cathaysia Regions. The Cathaysia Region is a hierarchy category and includes the South China, North China, and Tarim-Qilianshan Provinces. This floristic region is characterized by some Asian endemic plants, including Tmgza,

Tin^ostachys, Alethopteris, Cathaysiodendron, Lobatanntdaria, Emplectopteridium, and gigantopterids, as well as other endemic species. This region is dated from the Late

Carboniferous to the end of the Permian or elongated into the earliest Triassic.

With megafossil plant data, Permian phytogeography is reconstructed (Figs.

201 and 202). The Angara Kingdom is in the northern hemisphere, and the

Gondwana Kingdom in the southern hemisphere. The Pan-Tropical Kingdom is roughly along the equator, and, from west to east, is divided into the Western North

America Region, the West Paleo-Tethys Region, and the Cathaysia Region. The last region includes most blocks in the East Paleo-Tethys (in the southern hemisphere), the South China Province (just south of the equator), and the North China and the

155 Tarim-Qilianshan provinces (in the northern hemisphere). The South China

Province is represented on three major blocks: The South China Block is on the

equator and in contact with the Indochina Block on its southern side during the entire Permian; the North Tibet Block should be close to the SCB to allow the

Cathaysian elements, especially the gigantopterids, to migrate. The Gondwana

Sibumasu Block and the mixed Gondwana-Cathaysia New Guinea flora are between

Indochina and Australia. The Mixed Gondwana-Cathaysia Flora in Turkey occurs between northern and southern Tibet, but closer to northern Tibet or the SCB.

South Tibet might be closer to Australia and India of the Sibumasu Block because of the occurrence of Glossopteris. Middle Tibet might be surrounded by Turkey,

Saudi Arabia, and southern Tibet. Beginning in the late Early Permian, the collision between SCB and NCB caused some mixed South-North floras to develop along the

Xu-Huai-Yu zone. The southern Gigantopteris found at Mengcheng, northern Anhui

Province, and Yuxian, southern Henan Province might just be the evidence for this collision.

The Tarim-Qilianshan Province was a bridge between North China and

Western Europe, and probably separated from Western Europe in the Late

Carboniferous, drifting toward the Kazakhstan Block. The flora was Cathaysian in

nature from the early Early Permian to the early Late Permian, but became a mixed

Cathaysian-Angaran type after Tarim-Qilianshan coalesced to the Kazakhstan Block by the late Late Permian. As a result, the dominant plants of the Tarim-Qilianshan flora changed from Euramerican, to Cathaysian, and finally to Angaran. The

156 Permian climate in northwestern China became arid resulting in no migration for the gigantopterids. The Late Permian climate in the North China Province turned arid or semiarid so that Gigantopteris was prevented from spreading northward, although the North China Block had not yet reached the Siberian shield by the close of the

Permian.

Some mixed Cathaysia-Euramerica floras (Unayzah of Saudi Arabia and

Spain) were located in the western part of the Paleo-Tethys. Subsequent research on these mixed floras will be important in more accurately defining paleobiogeographic reconstructions, and this will help to clarify the migration pathways between different floras.

157 CHAPTER IX

GENERAL DISCUSSION

The present fossil plants collected from western Guizhou Province, China, provide a great deal of morphological and anatomical data about gigantopterids.

With these data, a relatively comprehensive understanding of gigantopterids has been made, including their morphology, anatomy, ecology, and systematic position, as well as their geographic distribution.

Reconstruction of Gigantopterid Plants - Before this investigation, our knowledge of gigantopteroids was limited to their foliar morphology and a small amount of foliar anatomy. Now, this research has not only recognized a new actinodromous leaf pattern and added some new foliar anatomic data, but also reported both morphology and anatomy of their stems, synangia, and their potential seeds. Significantly, most data are gained from a single rock specimen, which contains very few other plants. This makes it more convincing to reconstruct the individual organs together based on their organic connection and anatomical similarities. To confirm the reconstruction, other associated taxa have been excluded. With these data, the morphology and anatomy of the Late Permian gigantopterids of western Guizhou have been summarized as follows.

158 Generally, gigantopterid leaves vary in size, shape, margin, and venation

(Chapter III). All gigantopterids can be divided into two patterns (pinnate and actinodromous) and five types (C-, E-, G-types in the former; tri- and quinque- nerved in the latter). Gigantopterid leaves of the present collections include all G- type, including simple mesh {Gigantonoclea) and compound mesh (Gigantopteris) subtypes. Actinodromous gigantopterids have not been named and all have compound mesh venation. These leaves commonly have sclerenchyma ribs beneath the hypodermis and an endodermis in major veins, and paracytic stomata on the

abaxial surface (Chapter IV). Gigantonoclea has spines over major veins, while

Gigantopteris might have some hook-like structures modified from entire leaves.

Two genera of permineralized gigantopterid axes have been established. Both have vertical sclerenchyma ribs beneath hypodermis, an endodermis enclosing a eustele that is composed of mesarch axial strands (primary xylem) and secondary xylem. Spinivinea has spines, endodermis, and tracheids, while Vasovinea bears hook­ like and/or tendril-like structures, and has vessels in the metaxylem and secondaiy xylem. Vessels in the metaxylem have scalariform perforation plates, while vessels in the secondary xylem are large, up to 500 pm in diameter, with foraminate-like perforation plates. Spinivinea has been linked with Gigantonoclea. While the vessel- bearing Vasovinea has been temporarily related to Gigantopteris.

Some compressed seeds of Carpolithiis speculatus have been found associated with gigantopterids. Most of them are elliptic or ovate, 9-11 mm long and 5-6 mm wide, with a smooth surface, rounded apices and bases. The seeds have short stalks

159 that are closely pointed towards, or attached to, a primary or a secondary vein of gigantopterid leaves on the abaxial side. These suggest that C. speculatus might be the potential seeds of gigantopterids. However, several types of permineralized seeds from the same sites were poorly preserved and provide no evidence to support this assumption, although they are also associated with gigantopterids.

Hundreds of isolate synangia, Guizhoutheca inanibasis, have been found in the rock associated with gigantopterid leaves and stems. They are bilaterally symmetrical, and consist of a ring of 9-14 elongated sporangia on a hollow base, which sometimes contain some filament-like structures. Sporangia surround a central vascular column. Vascular tissue extends from the stalk, through the basal side and the top wall, entering into the central column. Synangia of Guizhouthecal sp. are found attached to the secondary veins on the abaxial surface of a folded gigantopterid leaf. The sporangia of each synangium are arranged in two rows, but this might be a deformed appearance. Since both G. inanibasis and Guizhouthecal sp. are similar in some synangiate features and have similar palynomorphs, both are suggested to belong to the gigantopterids.

Ecology of Gigantopterids - These gigantopterids have been suggested to be liana plants growing in a Permian tropical rain-forest, based on their morphology and anatomy. They have very slender stems, often less than 1 cm in diameter. Their leaves seem too large for such slender stems, but they have mechanical adaptations to support the heavy leaves. Gigantonoclea plants have numerous spines on the dorsal side of midrib and on stems (Rhizomopsis and Spinivinea). Gigantopteris plants

160 have larger leaves with rare and smaller spines, but with more efficient hook-like and/or tendril-like structures which may help them hang on woody trees steadily.

Gigantonoclea guizhouensis might have grown in the understory layer, so palisade tissue was not well developed in the leaves because of the dim and damp niche. Higher environmental moisture is also suggested by water-storage cells found on the end of freely ending veinlets, secretory cavities embedded in the mesophyll, and the radial thickenings on the walls of the stomatal guard cells. In such a situation, plants do not need very efficient water conducting tissue. Thus, only tracheids are developed in the stems.

On the other hand, Gigantopteris plants have cordate-shaped large leaves, which might grow in a canopy layer, as those in extant tropical lianas. To adapt to the intense sunshine, the leaves developed 2-3 layers of palisade cells. The stomata are more or less sunken below the epidermis, and the stomatal guard cells lack radial thickenings so that the guard cells could easily close to prevent water evaporating.

Such a large leaf surface would cause high evapo-transpiration, which requires a very efficient water-conducting tissue. The occurrence of vessels in Vasovinea stems appears to meet these requirements.

Although both Gigantonoclea and Gigantopteris might grow in the same region, even same niche, they appear to be adapted to their special growth layers. It may be that adaptation to the environment is the cause that the gigantopterids to diverge not only morphological, but also systematically.

161 Systematic Affinities -- Gigantopterids have been thought as true ferns

(Schenk, 1883) and seed ferns (Halle, 1927, 1929; Asama, 1959). Systematically,

Asama (1974) proposed gigantopterids as an ancestral group of angiosperms, since

their broad simple leaves are similar to those of angiosperms. Li, X. and Yao (1983)

considered gigantopterids to be seed ferns, but parti-angiosperms in nature, based

on their restoration of the seed structure of Gigantonomia. However, none of these

assumptions have been supported with convincing, structurally preserved reproductive

organs. The present investigation provides many structurally preserved leaves, stems

and synangia of gigantopterids, as well as their potential seeds preserved in

compressions and impressions. These materials provide much evidence to

demonstrate their possible systematic attribution and suggest evolutionary trends.

First of all, the gigantopterids appear to be an artificial group. Some C-type gigantopterids (e.g., Gigantopteridiiim sp.) may belong to seed ferns, since they are morphologically similar to Aipteris, Aipteiidium, and Callipteris and have the same type of stomata (Yao and Crane, 1986; Yao and Wang, 1991). On the other hand, since many C-type gigantopterids have taeniopteroid leaves, and many taeniopteroids have been suggested to belong to the Marattiales. Therefore, the possibilities of some C-type gigantopterids being marattialean plants can not be excluded. Some E- type (e.g.. North American Delnortea abbottiae) have been suggested to be comparable with Gnetum (Mamay et al, 1989).

The present gigantopterids from western Guizhou includes only the pinnate

G-type and actinodromous types. The actinodromous gigantopterids with compound

162 meshes appear to be differentiated from the G-type with compound meshes. While the actinodromous ones with simple meshes might also have derived from the G-type one with simple meshes. Considering leaf architecture, simple leafed G. nicotianaefolia can be comparable to Gnetum to some extent; while some actinodromous leaves resemble certain angiosperms. Anatomically, Gigantonoclea and Gigantopteris are similar to some Carboniferous seed ferns in their epidermal cells and tracheids, although their stomatal types and xylem configurations differ.

This suggests both genera might have evolved to seed fern level at least. On the other hand, both genera appear to be related since both have similar sclerenchyma strands beneath hypodermis and have an endodermis in major veins. Both gigantopterid axial genera Spinivinea and Vasovinea also show the similar sclerenchyma strands, beneath the hypodermis, and endodermis, and suggest, again, that both might be related in origin. However, the former has developed only tracheids, while the latter has vessels in the xylem. These differences may suggest that both diverged along different evolutionary paths. Importantly, Vasovinea exhibits scalariform pits on lateral walls and scalariform perforation plates on end walls of metaxylem elements. It also shows and multiseriate circular bordered pits

(without tori) on the lateral walls and foraminate-like perforation on the end walls of secondary vessel elements. These features make the taxon resemble both gnetophytes and angiosperms. So, it appears to have evolved to the anthophyte plant level, and might be a common ancestral group for both groups, based on vegetative features only.

163 Two types of synangia have been associated with the gigantopterids in the present material. Synangia of Guizhouthecal sp. are simpler than those of

Gigantotheca, but both are similar to those of Marattiales to some extent.

Guizhoutheca inanibasis synangia are different from those of Marattiales, seed ferns, and gigantopterid Gigantotheca. Each synangium consists of a ring of sporangia surrounding a central vascular column on a hollow base, and appears to be more elaborate than all known seed ferns. On the other hand, Carpollthus speculatus has been suggested as a potential gigantopterid seed. This type of seeds is different from the Gigantonomia reported from Fujian Province by Li, X. and Yao (1983).

Therefore, the present G-type and those gigantopterids of Li, X. and Yao (1983) might be polyphyletic.

In conclusion, vegetative features of gigantopterids suggests that they may have evolved to an anthophyte level. However, the reproductive organs are not comprehensively understood, and provide insufficient evidence to fully support this hypothesis. Considering that no angiosperms have been found from the Jurassic and

Triassic, the present Permian gigantopterids seem too old to be the ancestral groups of angiosperms. It is hard to prove whether gigantopterids, angiosperms, and gnetophytes are related homologously or just are convergent (homoplasy).

Nevertheless, it seems likely that the compound mesh G-type the and actinodromous gigantopterids might have evolved to a level roughly equal to that of anthophytes

(gnetophytes and angiosperms).

164 Geography of Gigantopterids - The distribution of gigantopterids is very interesting since these plants have been found in both Southeast Asia and western

North America. To recognize this special distribution, the Gigantopterid Biome is established to combine the vegetation in the two disjunct areas into one community pattern. The Gigantopterid Biome is defined by the presence of a traditional

Gigantopteris Flora, which existed from the Early Permian to possibly the early Early

Triassic. Geographically, this biome includes the Permian Period of the South China and North China Provinces in the Cathaysia Region and the Texas Province of the western North America Region.

This distribution also leads to a new phytogeographic classification of the Late

Paleozoic. The traditional Cathaysian and Euramerican floras, plus the western

North America flora, are redefined as three Regions and are combined together into a Pan-Tropical Kingdom. The Cathaysia Region extended from the Late

Carboniferous to the end of the Permian and possibly into the early Early Triassic.

This region is also characterized by gigantopterids, and divided into South China,

North China and Tarim-Qilianshan Provinces. However, the latter has no gigantopterids, so it does not belong to Gigantopterids Biome.

The Mixed Cathaysia-Gondwana floras in the South Paleo-Tethys provide witness not only to continental drift, but also to the migration of gigantopterids.

Similarly, the Mixed Cathaysia-Euramerica floras in West Paleo-Tethys suggest some potential westward migration of gigantopterids from Asia to North America. Two new reconstructions of Paleozoic phytogeography have been completed based upon

165 the plant megafossils. Further investigation of these mixed floras may provide additional information to reshape the phytogeography.

In short, for the first time, this research has completed a relatively comprehensive paleobiological study of gigantopterids. Gigantopterids are demonstrated as a very important group of Permian fossil plants. Their vegetative morphology and anatomy exhibit many highly derived features and suggest that the group may have evolved to a level equal to that of anthophytes. However, their phylogeny need to be further studied using better structurally preserved reproductive organs.

166 APPENDICES A

TABLES

Table 1. Koidzumi's (1936) Classification of Gigantopteridaceae

Subfamily Genus & Species Original Name (G. = Gigantopteris) Palaeogoniopteris G. mengkarangensis mengkarangensis Jongmans et Gothan, 1935 Palaeogoniopteridieae Gigantopteridium americamG. americana White, 1912 Zeilleropteris yumanensis G. nicotianaefolia Zeiller, 1907 G. dentata Koiwai, 1917 (in Yabe, 1917) Gothanopteridieae Gothanopteris bosschanaG. bosschana Jongmans et Gothan, 1935 Cardioglossieae Cardioglossum antiguum G. antigua Kawasaki and Kon’no, 1933 Cathaysiopteridieae Cathaysiopteris whitei G. whitei Halle, 1927 Gigantonoclea lagrelii G. lagrelii Halle, 1927 Gigantopteris nicotianaefolia Schenk, 1883 Gigantopteridieae Gigantopteris persica Kodaira, 1930 Gigantopteris longifolius Kodaira, 1930 Gigantopteris elongatus Kawasaki, 1932 Gigantopteris yabei Kawasaki, 1934 Gigantopteris koiwaiana Koidzumi, 1936

167 Table 2. Asama's Gigantopteridaceae and the three Evolutionary Series (Based on Asama, 1959)

Konnoa Emplectopteridium Emplectopteris Series Series Series (Konnoideae (Gigantopteroideae (Emplectopteroideae Subfamily) Subfamily) Subfamily) Third stage Gigantopteris Tricoemplectopteris* (Tricohetent leaf) nicotianaefolia taiyuanensis Û Û Second stage Bioemplectopteridium* Bicoemplectopteris * (Bicoherent leaf) longifolium hallei e e First stage Cathaysiopteris ? Gigantonoclea (Unicoherent leaf) whitei lagrelii D ft Initial stage Konnoa Emplectopteridium Emplectopteris penchihuensis** aiatum triangularis

* = Gigantonoclea Koidzumi (1936); ** = Callipteris tachingshanense Gu et Zhi (1974)

168 Table 3. A Partial List of Gigantopterids

Gigantopterids found in North America; G. hallei (Asama) Gu et Zhi, 1974 Cathaysiopteris yochelsonii Mamay, 1986 G. kaipingensis Gu et Zhi, 1974 Delnortea abbottiae Mamay et al., 1988 G. lagrelii (Halle) Koidzumi, 1936 Evolsonia texana Mamay, 1989 G. lobata Gu et Zhi, 1974 Gigantonoclea sp. Mamay, 1988 G. llongifolia (Koidzumi) Gu et Zhi, 1974 Gigantopteridium americanum (White) G. meridionalis Li et Yao (in Li, X et al, 1982a) Koidzumi, 1936 G. mira Gu et Zhi, 1974 Zeilleropteris wattii Mamay, 1986 G. paradoxa Mo, 1980 (in Zhao et al, 1980) Gigantopterids found in China, Korea, Japan, G. plumosa Mo, 1980 (in Zhao et al., 1980) and southeastern Asia: G. rosulata Gu et Zhi, 1974 Cathaysiopteris whitei (Koidzumi, 1936) Gu et G. rotundifolia Yang, 1987 Zhi, 1974 G. spatulata Yang, 1987 Cathaysiopteridium fasciculatum Li, 1989 (in G. taiyuanensis (Asama) Gu et Zhi, 1974 Huang, L. et al, 1989) G. tenuinervis Yang, 1987 Gigantopteridium sp. (Yao and Wang, 1991) G. yabei Kawasaki, 1934 Gigantonoclea (Koidzumi) Gu et Zhi Gigantonomia fukienensis (Yabe et Oishi, 1938) (= Bicoemplectopteris Asama, 1959 Li et Yao, 1983 and Tricoemplectopteris 1959) Gigantopteris (Schenk) Koidzumi G. acuminatiloba (Shim.) Gu et Zhi, 1974 G. cordata Yabe et Oishi, 1938 G. anfuensis Liang, 1988 G. dictyophylloides Gu et Zhi, 1974 G. alata Li, 1989 (in Huang, L. et al., 1989) G. meganetes Tian et Zhang, 1980 G. cathaysiana Yang, 1987 G. nicotianaefolia (Schenk, 1902) Yao, 1983b G. cladonervis Li, 1989 (in Huang, L. et al., G. cf. nicotianaefolia (Schenk, 1902) Li, X. et 1989) al, 1982b G. colocasifolia Yang, 1987 Gigantotheca paradox Li et Yao, 1983 G. crassa Zhu et Feng, 1992 Linophyllum xuanwe iensis Zhao, 1980 (in Zhao G.? curvinervis Li, 1989 (in Huang, L. et et al, 1980) al., 1989) Neogigantopteridium spiniferum Yang, 1987 G. dehuanensi Li, 1989 (in Huang, L. et al, Progigantopteris brevireticulatus Yang, 1987 1989) Zeilleropteris yunnanensis (Zeiller, 1907) G. guizhouensis Gu et Zhi, 1974 Koidzumi, 1936

169 Table 4. Correlation of the Upper Permian Formations of Shuicheng and Fanxian, Guizhou

(Fr. = Formation)

Series Age Shuicheng Panxian

Lower Triassic Griesbachian Feixianguan Fr. Feixianguan Fr. Changxingian Wangjiazhai Fr. Upper Xuanwei Fr. Upper Permian Longlanian Longtan Fr. Lower Xuanwei Fr. Emeishan Fr. Emeishan Fr.

Table 5. Plant Assemblage Zones in the Upper Permian of Panxian (Modified from Tian et al., 1990).

Late Zone B: Ullmamia-Podozamites laclolatus assemblage Changxingian Middle Zone A: Subzone d. Guizhoua gregalis Early Gigantonoclea - Gigantonoclea hallei assemblage guizhouensis Subzone c. Strigillotheca fasciculata Late - Lobatannularia - Pelourdea contracta assemblage multifolia Subzone b. Gigantopteris nicotianaefolia Longlanian - Gigantopteris - Pecopteris sahnii assemblage dictyophylloides Subzone a. Abrotopterisguizhouensis Early assemblage - Plagiozamites oblongifolius - Pecopteris Sahnii assemblage

170 Table 6. Directory of Compression and Impression Specimens used in the Dissertation

Location Specimen Taxa or Structure Figure

Dahebian D-2 Gigantonoclea guizhouensis 74, 77 LL-1 Gigantonoclea guizhouensis 53-55 LL-5 Even pinnate of Gigantonoclea 23 Laoyingshan LL-6 Carpolithus speculatus 150 Gigantonoclea of. longifolia. 24, 52 LL-7 Gigantonoclea lagrelii 48 Gigantopteris nicotianaefolia 34,47, 50 LW-01 Gigantonoclea sp. 25,44 LW-05 Carpolithus speculatus 152 LW-06 Carpolithus speculatus 150 Wangjiazhai LW-12 A trivemate leaf 57 LW-13 An ovate leaf 46 LW-16 Gigantonoclea guizhouensis 45 LW-25 Carpolithus speculatus 149 PLYOl Gigantonoclea sp. 66 PLY05 Rhizomopsis gemmifera 106 PLY07 Gigantopteris sp. 36,65 PLY08 Gigantonoclea sp. 43 PLY09 Gigantopteris dictyophylloides 60.61 L9401 Gigantopteris meganetes 41,62, 63 L9426 Rhizomopsis gemmifera. 104 Yueliangtian L9436 A quinquenerved leaf 70 L9445 Rhizomopsis gemmifera. 105 Pinnate leaf of IGigantopteris 31,51 L9447 Carpolithus speculatus 153-155 Carpolithus speculatus 156-157 L9448-1 Two unusual (productive?) structures 151 L9448-1 A trinerved leaf 69 L9448-2 Hook-like structure 108 L9449 Gigantopteris meganetes 67 The Swedish Museum No. 1426 Carpolithus speculatus seeds 164-168 of Natural History. associated with Gigantonoclea hallei No. 571 Gigantonoclea sp. 27

171 Table 7. Directoiy of Dissected Permlneralized Specimens

Location Specimen Slide/Slab Taxa or Structure Figure Gigantonoclea guizhouensis 90-91 Dahebian D-1 #1 Gigantonoclea guizhouensis 75-76, 81, 86-87 #2 Gigantonoclea guizhouensis 83,92 Wangjiazhai LW-02 #1 Carpolithus speculatus 160 Laoyingshan LL-2 Permineralized Seed. 162 #2a-l Pecopterid leaf with synangia 195 L9405 #2a-2 Pecopterid synangia, palynomorphs 194,196-197 Yueliangtian #D-T2 Vasovinea tianii 132 L9407 #C-B16 Vasovinea tianii 133, 135, 138 Permineralized seed 163 Rhizomopsis gemmifera 107 Guizhoutheca inanibasis 180 #A Spinivinea yunguiensis 122,131 #Al-I-2-2 Spinivinea yunguiensis 127-128 #Al-2-l-2 Spinivinea yunguiensis 119 #A2-3-3-2 Spinivinea yunguiensis 129 #A2-3-3-Pl Spinivinea yunguiensis 130 #A2-3-4 A pecopterid frond 191-193 #A2-P1-1 Spinivinea yunguiensis 126 #Cl-2-2 Permineralized seed 161 #C(R) Gigantopteris dictyophylloides 100 #C4(R) Guizhoutheca inanibasis 171 #C4-4 Guizhoutheca inanibasis 174 #C4-5 Guizhoutheca inanibasis 173 PLY02 #C4-3 Palynomorphs of G. inanibasis 181-182 SlabC4 Palynomorphs of G. inanibasis 185 #C5(R) Palynomorphs of G. inanibasis 183 #C6 Guizhoutheca inanibasis 177 #C6(R) A synangium with five sporangia 190 #C7(2T-1) Guizhoutheca inanibasis 176 #C7-6T Spinivinea yunguiensis 123-125 #C-7a side 2 Gigantonoclea guizhouensis 89 #C8(R)-2 A hook-Iike structure 109 #C9(T)-1 Guizhoutheca inanibasis 169-170 #C9(L) Guizhoutheca inanibasis 172 Slab CIO Guizhoutheca'! sp. 187 #C10(1-1) Vasovinea tianii 144 #C10(L)-1 Spinivinea yunguiensis 112 #C10(L)-2 Spinivinea yunguiensis 110,120 #C10(L-A) Guizhoutheca inanibasis 175 #C10(L-A)-2 Guizhouthecal sp. 187 #C10-2 Gigantopteris dictyophylloides 95, 99

172 Table 7. Directory of Dissected Permineralized Specimens (Continued)

Location Specimen Slide/Slab Taxa or Structure Figure

#C10-3 Gigantopteris dictyophylloides 94 #C10-4-l Gigantopteris dictyophylloides 96 111,113,114. #C10-4S1 Spinivinea yunguiensis 116-118 #C10-4S2 Spinivinea yunguiensis 115 #C10-6 Gigantopteris dictyophylloides 93 #C-llside 1 Gigantonoclea guizhouensis 85 #C-llside Gigantonoclea guizhouensis 88 #CI4(T) A folded gigantopterid leaf 189 #C15-(R-A) Spinivinea yunguiensis. 121 Yueliangtian PLY02 #C18-103 Permineralized seed 158-159 #D-1 side 1 Gigantonoclea guizhouensis. 84 m Vasovinea tianii 147-148 Vasovinea tianii. 146 #E4-2 Gigantopteris dictyophylloides 97-98,101 #H'-3 Gigantonoclea guizhouensis 79 #H'-4 Gigantonoclea guizhouensis 78,82 m '-5 Gigantonoclea guizhouensis 80 Gigantopteris meganetes 58, 136 #01 Vasovinea tianii 143 PLY03 #07 Vasovinea tianii 141 #06 Vasovinea tianii 142 #11 Vasovinea tianii 137 #34 Vasovinea tianii 145 PLY04 #B Vasovinea tianii 134 #06 Vasovinea tianii 140

173 Table 8. Classification of Gigantopterid Venation

Major Vein Pattern Type Mesh-lype Leaf Type Example

Cathaysiopteris white Compound C-Type (GuetZhi, 1974; Figs. 7-8)

Cathaysiopteridium fasciculatum Simple (S. L i, 1989*; Figs. 12-14) E-Type Simple Evolsonia texana (Mamay, 1989) Gigantonoclea hallei Compound Simple (GuetZhi, 1974; Figs. 18-19) Pinnate Gigantonoclea guizhouensis Simple G-Type (Li et al., 1994c; Fig. 73)

Gigantopteris nicotianaefolia Compound Compound (Tian and Zhang, 1980; Figs. 32, 56) Gigantopteris nicotianaefolia Simple (Yao, 1983b; Figs. 34-35, 71) Simple Simple An assumed actinodromous leaf (Fig. 66)

Trinerved Gigantopteris cordata Actinodromous Compound Simple (Tian and Zhang, 1980; Figs. 38, 40,68) Quinquenerved Compound Simple (Unnamed; Fig. 70)

(* In Huang et al., 1989.) Table 9. Seed-bearing pteridosperms from China

Taxa Description Occurrence Ref.

Alethopteris norinii Halle Oblong-lanceolate, 40 X 12 mm; on midrib. Foliage with black dots. L. Shihhotse, Taiyuan. [3-4] Fascipteridium elUpticum Oval, 3.5 X 2.5 mm w/ a narrow marginal rim, surface smooth, placed near the Permo-Carboniferous, [5] Zhang et Mo margin of the piima, with their long axis parallel to the secondary veins. Henan. Emplectopteris triangularis Ovate to elliptical, bicomute, 4 X 3 to 7.5 X 4.5 mm; On pitmular base on the L. Shihhotse, Taiyuan [2-4] Halle upper side; foliage with black dots. Sphenopteris tenus Schenk Seeds on the ultimate rachis, ovate or long ovate (4-5 X 2-2.5 mm) round base, Shuo-Hsien, Shansi. [1-4] protracted apex. Sphenopecopteris beaniata 6 X 5 nun, ovoid, broadly truncated base, with apical short truncate snout; Permo-Carboniferous, [5] âiang et Mo crowded swelling on surface; On upper side of the ultimate piimule. Henan. Pecopteris punicoides Zhang Globular, 11X10 nun; w/ basal projection, 2 X 2 nun & apical projection (3 X Permo-Carboniferous, [5] et Mo 2 nun) with 2 pointed horns. Perhaps on ultimate pirma rachis. Henan. Pecopteris wongii Halle Coimected with a frond by a 7 nun long recurved stalk; flattened, ovate, 7 X 4 L. Shihhotse, Taiyuan [3-4] mm. Cladophlebis henanensis Seed cylindrical, 4 X 1.2 nun, smooth; attached on the Upper surface of the Permo-Carboniferous, [5] Zhang et Mo piimule near the margin. Henan. Cladophlebis parapermica Two “seeds” on the distal lateral margin of some fertile piimule. Permian, Yunnan and [6] Zhang Guizhou Nystoemia pectinformis Halle Platyspermic bicomute type; 2-3 nun L., flattened, long obovoid to obconic; L. Shihhotse, Taiyuan [2-4] flattened. Synangia in uniseriate rows.

[1] Schenk, 1883; [2] Halle, 1927; [3] Halle, 1929; [4] Gu and Zhi, 1974; [5] Zhang and Mo, 1979; [6] Zhao et al., 1980. Table 10. Plant Assemblages of North and South China*

Age Northern Subprovince Southern Subprovince 5) Proposed but unnamed 5) Ullmannia cf. bronnii later Late Permian plant assemblage - Gigantonoclea guizhouensis 4) Gigantonoclea hallei 4) Gigantopteris nicotianaefolia early Late Permian - Fascipteris spp. - OtofoUum spp. - Lobatannularia ensifoUa - Lobatannularia multifolia 3) Emplectopteris triangularis 3) Gigantopteris fukienensis late Early Permian - Taeniopteris spp. - Tingia cabonica - Cathaysiopteris whitei 2) Emplectopteris triangularis 2) Emplectopteris triangularis early Early Permian - Taeniopteris spp. - Taeniopteris multinervis - Emplectopteridium aiatum 1) Neuropteris ovata \) Alethopteris hallei Late Carboniferous - Lepidodendron posthumii - Lepidodendron posthumii

(* Based on Li, X. 1980; Li, X. and Yao, 1985.)

Table 11. The Distribution of some Key Gigantopterid Genera in China

Type Genus Distinctive Characteristics SC M NC

C-type Cathaysiopteris Entire or undulated margin, no nets formed by veinlets X X Cathaysiopteridium Dentate margin, fascicular veinlets netted at bases X

G-type Gigantonoclea Simple meshes X X X Gigantopteris Compound meshes X X

NC = North China; SC = South China; M = the mixed south/north Yuxian flora, (based on Huang, L. et al., 1989; Mei et al., 1995; Yang, 1985,1987.)

176 Table 12. Correlation of Lower Permian Gigantopterids between North American and China

Time North America*" Fujian Province. South China*^' Henan Province, North China®

Series Floral Zones Fonnalion Gigantopterids Formation Member Gigantopterids Formation CM Gigantoptends

Dalong Sanfengshan

8 Gi. rosulata. G, crasiglandula Upper G i densireticulatus.Gi. spatualata

Permian Cuipingshan Yungaishan 7 G% nicotianaefolia. Gi. latiovata

6 Gi. hallei. G|. rotundifolia. Gi. sp.2, Gi. colocasifolia. Gi. mucronata Choza Cathaysiopterium 5

Zone 15; Vale **Delnortea abbottiae Gi yabei Gi. cathaysiana. Evolsonia texana 3 Gi fukienensis. 4 Gi. tenuinervis. *Cathaysiopteris Gi cordata Gi. deltata. G\,yabei. Younger yochelsonii Gi dictyophylloides Gz Clathroreticulatus Gigantopteris Arroyo Progigantopteris brevireticulatus flora l/)w er Leonardian Lenders Zeilleropteris wattii Tongziyan 2 XiaofengHou Gi. mira

Pennian Zone 14: Clyde Gi, americanum Gi. mira:. 1 Gispp. 3 Older G i cathaysiana. Gigantopteris Belle Gi. americanum G i. xiaofengkouensis. Gi spp. Flora Plains Gi sp. Gi sp. 1 Wolfcampian Zone 13; Wenbishan Shengou 2 Cathaysiopteris whitei

Callipteris spp. Qixia

Upper Chuanshan Zhutun 1 Carboniferous

‘'^ased on Read and Mamay, 1964; Mamay, 1968, 1986, 1988, 1989; Mamay et al., 1988. Based on Huang, L. et al., 1989. ^^^ased on Yang (1985,1987). Gi — Gigantonoclea', (7% = Gigantopteris, = Gigantopteridium', CM = Coal Member. * Lower Vale Formation; ** upper Vale Formation. Table 13. Stratigraphie Classification of the Upper Paleozoic in North China Province (Based on Editorial Group of "Geography of China," 1986; Li, X. and Yao, 1985).

Age Formations Plant Assemblages

late Shiqianfeng 5) Proposed but unnamed plant assemblage

Late early Upper Shihliotze 4) Gigantonoclea hallei - Fascipteris spp. - lobatannularia ensifolia Permian Early late Lower Shihhotze i) Emplectopteris triangularis - Taeniopteris spp. - Cathaysiopteris whitei

early Shanxi 2) Emplectopteris triangularis - Taeniopteris spp. - Emplectopteridium aiatum

Late Taiyuan 1 ) Neuropteris ovata - Lepidodendron posthumii

Carboni­ ferous Middle Benxi Euramerican flora

Table 14. The Nanshan Flora in Tarim-Qilianshan Province

Total Catliaysia Euramerican Angara Time Formation taxa taxa (%) taxa (%) taxa (%) Bexell's Strata (1937) M. Jurassic L. Jurassic Coniopteris sp. 8. Plant-bearing Zone D, 300m± U. Triassic Yanchang 7. Red or green sediments, 500m + M. Triassic Group L. Triassic Annalepis sp. PleuroeiHis rossica

39 36% only 1 sp. 64% Jiayuguan 6. Plant-bearing Zone C, I00m+ Upper 65* 35%* 6%* 59%' 5. Transitional sediment zone, 150m±

Permian Xidagou 4. Red sediments, 450m+

Yaogou 28 dominant 2 - 4 spp. 2 spp. 3. Transitional sediment zone, 150m+

Lower Dahuanggou 32 62% 28% 9% 2. Plant-bearing Zone B. 200m+ Permian Tongwei 54 38% 62% 0 1. Marine sediments with intercala­ Upper tions of plant-bearing beds. Carboniferous Taiyuan Plant-bearing Zone A, 90m+

(* Based on Wang, D. et al., 1984; other data based on Wang, D. et al., 1986.)

178 Table 15. Qübu Flora in South Tibet

Hsü, 1976 Hsü et al., 1990

*Sphenophyllum speciosum (Royle) Trizygia speciosa Royle McCl. Sphenopbyllum minor (Sterzel) Gu et Zhi Giossopteris communis Feistm. Giossopteris communis Feistm. Glossopteris angustifolia Bgt. Giossopteris indica Schimper Giossopteris cf. indica Schimper Giossopteris dingriensis Rigby Giossopteris spp. Raniganjia qubuensis Hsü Austroannularia qubuensis (Hsü) Rigby Dizeugotheca qubuensis Hsü Pecopteris cf. unita Bgt. Dichotomopteris qubuensis Hsü Cladophlebis qubuensis (Hsü) Li Asterotheca sp. Paracalamites australis Rigby

(* Referred to Lobatannularia by Singh et al. f1982].)

Table 16. Phytogeographic Classification of Late Paleozoic

Kingdom Region Province Angara (Omitted) Central Alaska Western North America Western Roclg' Mountain Kansas Texas Pan-Tropical Eastern North America West Paleo-Tethys Europe Spain South China Cathaysia North China Tarim-Qilianshan Gondwana (Omitted)

179 APPENDICES B

FIGURES

Ail line drawings are followed by their references. Different sources for a few specimens or photographs are cited in figure captions.

Except a few specimens illustrated were loaned from the Swedish Museum of

Natural History. Most specimens were collected from four coal mines in western

Guizhou. The localities of these specimens are as follows:

D = Dahebian Mine, Shuicheng, Guizhou;

LL = Laoyingshan Mine, Shuicheng, Guizhou;

LW = Wangjiazhai Mine, Shuicheng, Guizhou;

L94 and PLY = Yueliangtian Mine, Panxian, Guizhou.

180 Beijing

oYuxian VII

Sicliunn VIII

Y unnan

Fig. 1. Map of China showing the tectonic blocks and the localities of gigantopterids used in this dissertation. I, Tianshan-Xingan Region of the Angaran Shield; II, Tarim-Qilianshan Blocks; III, North China block; IV, The region of the Kunlun-Qinling Sea (Late Paleozoic); V, Yangtze Block (= South China Block or SCB); VI, Qiangtang Blocks; VII, Middle Tibet Block; VIII, South Tibet Region of India Block. The shaded region is the Yun-Gui-Chuan coal field. 1, Shuicheng; 2, Panxian; 3, Liuzhi.

181 N A

J Shuicheng

j \ ) ./ // / L. YUNNAN GUIZHOU / O Liuzhi

\ \ y / Yueliangtian Mine I i L Xiaohebian Synciine n. Dahebian Synciine j 1. Wangjiazhai Mine 2. Dahebian Mine o r 3. Laoyingshan Mine Panxian i \ Upper Permian V —I------1 30 km

Fig. 2. Map of the Liu-Pan-Shui District showing the four coal mines and the exposed Upper Permian strata around the mines.

182 Z h aoiung

Gui-Qian Sea—

Oianxi

W etning q Guiyang Zhi jin

Sh u ich en g

Liuzhi

Anshun Xuanw ei m iinnc limc- L angdai old sand bar sinne deposits

continental direction of with marine fossil current inicrbeddings

F u y u a n ( ' ' p a n x ia n coniincnia) location of deposits profile

Xingren o1 fossil stream Ir'"' I

n j a h iuan w ei W angjiazhaiXu A nshun

Fig. 3. Paleogeographic map of western Guizhou and eastern Yunnan during the Changxingian age, Late Permian. (Modified from Tian, 1979).

183 Laoyingshan Wangjiazhai Dahebian

Yueliangtian

s a

m

m

aas

Fig. 4. Correlation of Upper Permian formations of the four coal mines. (Modified from Tian and Zhang, 1980 and Tian et al, 1990.)

184 Figs. 5-16. Some gigantopterids from China (7-9, 12-14) and western North

America (5-6,10-11,15-16) showing leaf patterns and C-Type venation with sutural

veins (arrows). 5-6. Zeilleropteris wattii. 5, X 0.5; 6, X 2 (drawn from Read and

Mamay, 1964). 7. Pinnately compound Cathaysiopteris whitei from Shanxi, X 0.5

(drawn from Gu and Zhi, 1974). 8. Venation of C. whitei from Henan, X 2 (redrawn

from Yang, 1987). 9. Z. yunnanensis from Yunnan. X 2 (drawn from Zeiller, 1907).

10-11. Biforked Gigantopteridium americana. 10, X 0.5; 11, X 2 (drawn and modified

from White, 1912). 12-14. Cathaysiopteridium fasciculatum from Fujian. 12, X 0.5;

13-14, X 2 (drawn from Huang, L. et al, 1989). 15-16. Biforked Cathaysiopteris yochelsonii. 15, X 0.5; 16, X 2 (drawn from Read and Mamay, 1964).

185 186 Figs. 17-30. G-typed Gigantonoclea leaves with simple mesh venation. 17. G. rosulata. X 1.5 (redrawn from Gu and Zhi, 1974). 18-19. G. hallei. 18, X 1.5; 19,

X 0.5 (redrawn from Gu and Zhi, 1974 and Halle, 1929). 20. Black dots in meshes of G. lagrelii, X 1.5 (redrawn from Gu and Zhi, 1974). 21. G. sp. From Texas, X 0.5

(redrawn and modified from Mamay, 1988) 22. Small pinnae of G. meridionalis, X

0.5 (redrawn from Gu and Zhi, 1974). 23. Pinnately compound leaf with odd terminal leaflet, X 0.5 (drawn from specimen LL-5, from the Upper Permian, western Guizhou). 24. Pinnately compound leaf with even terminal leaflet, X 0.5

(drawn from specimen LL-7, from the Upper Permian, western Guizhou). 25.

Asymmetrical lamina, X 0.5 (drawn from specimens, LWOl [= Fig. 44], from the

Upper Permian, western Guizhou). 26. Ovate simple leaf, X 0.5 (drawn based on specimens, PLY08 [= Fig. 43] and LW-13 [= Fig. 46], from the Upper Permian, western Guizhou). 27. G. rosulata showing narrow oblong leaf shape and acute apex,

X 0.5 (drawn from Gu and Zhi, 1974). 28. G. sp. showing serrate margin and attenuate apex, X 0.5 (drawn from Halle, 1927 [= specimen No. 571, Swedish

Museum of Natural History]). 29. G. acuminatiloba showing a compound serrate margin, X 0.5 (redrawn from Gu and Zhi, 1974). 30. G. colocasifolia showing a simple leaf with an axillary bud, X 0.5 (redrawn from Yang, 1987).

187 188 Figs. 31-41. G-typed gigantopterids with compound mesh venation from

Hunan (33), Fujian (37), and the Upper Permian of Western Guizhou (others). 31.

An underdeveloped pinnate-pinnatifid Gigantopteris leaves, X 0.5 (drawn from specimen L9447 [= Fig. 51]). 32. Pinnate-pinnatifid Gigantopteris nicotianaefolia

(drawn from Fig. 56). 33-35. Entire-leafed Gigantopteris nicotianaefolia with pinnate venation. X 0.5. 33. Schenk's specimen from Hunan, X 0.5 (redrawn from Schenk,

1883); 34. Elliptical shaped leaf, X 0.5 (drawn from specimen LL-7 [= Fig. 47]);

35. A leaf with marginal loops, X 0.5 (redrawn from Fig. 49 [courtesy Y. Guo]). 36.

Gigantopteris sp. showing pinnate venation and round toothed margin, X 0.5 (drawn from specimen PLY07 [= Fig. 65]). 37. A small and asymmetrical Gigantopteris?

Cordata, X 0.5 (redrawn from Gu and Zhi, 1974). 38-40. Gigantopterids with actinodromous venation. 38. Gigantopteris cordata Tian and Zhang emend, X 0.5

(drawn from Tian and Zhang, 1980 [= Fig. 68]). 39-40. A quinquenerved leaf and a trinerved leaf with compound rounded teeth, X 0.5 (based on field photographs and sketches). 41. Venation of the specimen L9401 [Figs. 62-63]). X 1.

189 190 Fig. 42. Geological occurrence and hypothesized evolutionary trends of

Permian gigantopterids in Yuxian County, Henan Province, China (redrawn and modified from Yang, 1987).

191 C cd

I Gi. spatulata Gi. crassiglandula Gi. rosulata _ ! S3 Gz. densireticulatus a g •g iV. spiniferum , a I I K G i . latiovata Gi. mucronata Gi. colocasifolia g„ rolundifolia Gi. sp. 2 Gi. AaZZei & nicotianaefolia : \ . ' \ : Gz. clathroreticulatus

G i . j f a f c e i G i . tenuinervis G i . deltata g P. brevireticulatus \£> ro Ic

X G i . mira

I ? Gigantopteridium G i . catkaysiana G i . xiaofengkouensis

C. = Cathaysiopteris E. triangularis II Cathaysiopteris whitei E. kenanensis E. = Emplectopteris Gi. = Gigantonoclea CO Gz. = Gigantopteris Cathaysiopteris Series Emplectopteris Series N. = Neogigantopteridium III P. = Protogigantopteris Figs. 43-46. Some gigantopterid leaves from Guizhou. 43. Gigantonoclea sp. showing a serrate margin with round sinuses. PLY08, X 0.9. 44. An asymmetrical lamina of Gigantonoclea sp. LWOl, X 1. 45. Gigantonoclea guizhouensis showing a serrate margin and the reduction in width of lamina towards the base. LW-16, X 0.9.

46. An ovate leaf with serrate margin. LW-13, X 0.9.

193 194 Fig. 47. Different sized but similar Gigantopteris nicotianaefolia leaves preserved together. LL-7, X 0.9. Fig. 48. The associated Gigantonoclea lagrelii in

Fig. 47. X2.4.

195 195 Figs. 49-50. Gigantopteris nicotianaefolia. 49. A leaf from western Guizhou showing compound mesh venation, smooth margin, and apically curved secondaries

(courtesy Y. Guo). 50. Leaf apices found on the reverse side of specimen LL-7. X

0.9. Fig. 51. A smaller pinnate leaf. L9447, X 1.6. Fig. 52. A pinnately compound leaf similar to Gigantonoclea cf. longifolia. Reverse side of LL-7, X 0.9. Figs. 53-55.

Two petiolate leaves of Gigantonoclea guizhouensis borne on a spiny axis. LL-1. 53-

54. Many spines on the axis surface, X 0.9. 55. Enlargement of insert from Fig. 54, showing a higher magnification of a single spine on the axial edge. X 5.5.

197 198 Fig. 56. A pinnate-pinnatifid merging leaf of Gigantopteris nicotianaefolia (Tian and Zhang, 1980) from Wangjiazhai, Shuicheng, Guizhou (courtesy Baolin Tian).

X 0.9. Fig. 57. A right basal part of a trivernate leaf, LW-12, X 0.9. Fig. 58.

Gigantopteris meganetes with compound mesh venation which is also in the compound round teeth. This leaf is associated with a vessel-bearing stem (in Figs. 136-137).

PLY03, X 0.9. Fig. 59. A round trinerved leaf, photographed at the Wangjiazhai mine. X 0.9. Fig. 60. A broken leaf of Gigantopteris dictyophylloides with three secondaries of midrib at the upper part and one lateral primary vein at the right bottom. Both laminar parts are organically connected by a portion in the rock. Note the leaf with an incomplete compound tooth, in which secondary vein extends towards the major-tooth tip, while the tertiaries taper toward the minor-tooth tips

(arrowhead). Insert illustrated in Fig. 61. PLY09, X 0.9. Fig. 61. Enlarged venation details of the insert in Fig. 60. X 2.4.

199 200 Figs. 62-63. Gigantopteris meganetes. 62. Large lamina with a right basal lateral vein which is dimorphic from other secondaries. Insert illustrated in Fig. 63.

L9401, X 0.5. 63. Magnified compound mesh venation of the insert in Fig. 62. X

2.3. Fig. 64. A trinerved leaf with toothed basal lobes photographed at the

Wangjiazhai mine. X 0.9. Fig. 65. Gigantopteris sp. with pinnate secondary veins and compound mesh venation. Note the left basal lateral vein is shorter than those above it. PLY07, X 0.9.

201 202 Fig. 66. Gigantonoclea sp. showing an asymmetric lamina part with an arching vein which bears more but thinner ascending than those descending secondary veins.

PLY-01, X 0.6. Fig. 67. A leaf of Gigantopteris meganetes with compound round teeth. Note an associated hook in the matrix at the top. L9449, X 0.9. Figs. 68-70.

Several actinodromous gigantopterid leaves. 68. Gigantopteris cordata emended by

Tian and Zhang (1980) from Wangjiazhai, Shuicheng, Guizhou (courtesy Baolin

Tian). X 0.9. 69. A trinerved leaf with compound mesh venation. L9448-1, X 0.6.

70. The left basal side of a quinquenerved leaf. Note the two lateral primaries bear longer and thicker descending tertiaries. L9436, X 0.7.

203 68

204 Fig. 71. The venation of Gigantopteris nicotianaefolia. X 2.7. (draw from Gu

and Zhi, 1974). Fig. 72. A broken leaf of Gigantopteris nicotianaefolia Schenk. The major vein is a lateral primary vein which gives off more ascending secondaries than

descending ones (redrawn from Schenk, 1883. X 1). Fig. 73. Restored leaf of

Gigantonoclea guizhouensis showing expanded base (left) and detail of venation

(right) (Redrawn from Li, H. et al., 1994c).

205 Fimbrial vein

Secondary vein

sutural vein

Tertiary vein

Companion mesh Figs. 74-79. Gigantonoclea guizhouensis. 74. Portion of a compressed leaf showing midrib and several secondary veins. D-2. X 1.3. 75. Paradermal section of permineralized leaf showing secondary (S) and tertiary (T) veins. Note several circular secretory cavities. Insert illustrated in Fig. 76. D-1, slide #1, X 17. 76.

Detail of insert in Fig. 75 showing mesh venation, mesophyll cells and secretory cavities. D-1, slide #1, X 48. 77. Detail of venation in Fig. 74. Sutural vein extends between arrows. Black dots represent secretory cavities. D-2, X 6 (reprinted Li and

Tian, 1990). 78. Detail of permineralized leaf showing fimbrial vein (arrows) and mesophyll. PLY02, slide #H’-4, X 47. 79. Marginal vein (lower arrow) and dichotomizing smaller fimbrial veins (outlined by arrowheads). PLY02, slide # H ’-3,

X 68.

207 208 Figs. 80-88. Gigantonoclea guizhouensis. 80. Adaxial epideimal cells showing sinuous margins. PLY02, slide #H ’-5, X 327. 81. Abaxial epidermis showing two stomata. Note thickened inner guard cell walls (arrows). D-1, slide #1. X 408. 82.

Paradermal section viewed from inside showing palisade (dark) and adaxial epidermal cells with sinuous margins. PLY02, slide # H ’-4, X 327. 83. Transverse section of lamina with secretory cavity (arrow) in mesophyll. D-1, slide #2, X 49.

84. Transverse section of lamina with secretory cavity and trichomes (arrowheads).

PLY02, slide #D-1 side 1, X 163. 85. Transverse section of lamina showing palisade cells (left). PLY02, slide #C-11 side 1, X 163. 86. Section of leaf showing detail of possible water storage cell (W) with opening (arrowhead) and wall thickenings of tracheids in vein ending (small arrow). D-1, slide #1, X 41 (reprinted from Li and

Tian, 1990). 87. Detail of tracheids in secondary vein showing annular, helical and circular bordered pits. D-1, slide #1, X 204. 88. Transverse section of leaf midrib showing organization of U-shaped vascular strand. Arrowhead shows adaxial surface.

L = lamina. PLY02, slide #C-11 side, X 34.

209 210 Figs. 89-92. Gigantonoclea guizhouensis. 89. Oblique transverse section of a secondary vein and part of the lamina. Note U-shaped vascular strand and endodermis (arrow). Large bulge on adaxial surface represents oblique section of adjacent lamina. PLY02, slide #C-7a side 2. X 35. 90. Secretory cavity with contents. D-1, X 262. 91. Detail of tracheid showing circular bordered pits. D-1,

X 1098 (reprinted from Li and Tian, 1990). 92. Transverse section of midrib showing conspicuous multicellular spine on the abaxial surface, hypodermal sclerenchyma bands (arrows), and endodermis (E). D-1, slide #2, X 76 (reprinted from Li and

Tian, 1990).

211 'î

212 Fig. 93-96. Gigantopteris dictyophylloides. 93. Branched blind vein in an elongated net. PLY02, slide #C10-6, X 54. 94. A large mesh which encloses several small nets and branched bhnd veins in the nets. PLY02, slide #C10-3, X 48. 95.

Isometric upper epidermal cells. PLY02, slide #C10-2, X 400. 96. Upper epidermis with stoma. PLY02, slide #C10-4-l, X 400.

213 m ' â

Ë

9S

214 Figs. 97-101. Gigantopteris dictyophylloides. 97-98. Tracheids in a tertiary vein exhibiting various secondary wall thickenings. PLY02, slide #E4-2, X 625. 99. Two stomata from on the abaxial surface. PLY02, slide #C10-2, X 400. 100. Transection of a leaf showing two to three layers of short palisade cells (right). PLY02, slide

#C (R ), X 200. 101. Cross section of a secondary vein with a heart-shaped xylem segment enclosed by a poorly preserved endodermis layer (arrowhead). PLY02, slide

#E4-2, X 56.

215 ?

r'jkSüat^

216 Figs. 102-107. Rhizomopsis gemmifera. 102. A compressed axis with spines on the view face and edge (left). Photograph taken at the Wangjiazhai mine. X 3. 103.

An axis with vertical ribs and spines. Photograph taken at the Wangjiazhai mine. X

2. 104. An axis associated with a Gigantopteris leaf. Note the axis with vertical ribs but without spines. L9426, X 1. 105. An axis showing small spines and thin vertical striations. L9445, X 1. 106. A spiny stem with prominent spines and vertical ribs.

The stem is between two Gigantonoclea leaves. PLY05, X 1. 107. Longitudinal section of a permineralized stem showing anatomy of spines. PLY02, slide #D1, X

7.

Fig. 108. A hook-Uke structure which branches two times (arrows). Note a broken hook-tip part on left bottom. L9448-2, X 2.4. Fig. 109. Oblique longitudinal section of a permineralized hook-like structure. The right end shows the oblique- cross section of the hook as it recurves back, and the end has a fine hollow center.

PLY02, slide #C8(R)-2, X 20.

217 / r i .

p V mm 1 fl p I I

,tf ■■ 218 Figs. 110-118. Holotype of the Spinivinea yunguiensis. 110. Cross-section of

a stem with both primary and secondary xylem developed. PLY02, slide #ClO(L)-2,

X 6.7. 111. Cross section (upper) and longitudinal section with a spine. PLY02, slide

#Cl04Sl, X 9.6. 112. Oblique-cross section with mesarch primary xylem. PLY02,

slide #ClO(L)-l, X 115. 113-118. Longitudinal sections. 113. Primary xylem (left and center) and secondary xylem (right). PLY02, slide #ClO-4Sl, X 115. 114. Secondary xylem tracheids with multiseriate bordered pits and cross-field (upper). PLY02, slide

#Cl04Sl, X 115. 115. A tracheid with transversely elongated bordered pits. PLY02, slide #Cl04S2, X 202. 116. Primary xylem tracheids with annular and helical thickenings (left) and secondary xylem tracheids with multiseriate bordered pits

(center and right). PLY02, slide #Cl04Sl, X 192. 117. Secondary xylem tracheids with multiseriate bordered pits (left) and cross-field pits (right). PLY02, slide #ClO-

4S1, X 212. 118. Showing cross-field pits. PLY02, slide #Cl04Sl, X 192.

219 A

220 Figs. 119-125. Paratypes of Spinivinea yunguiensis. 119. Cross section of an axis with spines, sclerenchyma ribs in the outer cortex, and vascular bundles. PLY02, slide #Al-2-l-2, X 9.3. 120. Cross section of an axis with a spine (right) and a secretory cavity (center). PLY02, slide #C10(L)-2, X 6.5. 121. Cross section of a vascular bundle with mesarch primary xylem and secondary xylem. Note endodermal cells (e) at lower left. PLY02, #C15-(R-A), X 158. 122. Cross (upper) and longitudinal (lower) sections showing the sclerenchyma ribs, cortical cells, and endodermal cells (arrows) vertically linked into rows. PLY02, slide #A , X 53. 123-

125. Longitudinal sections of xylem. 123. Protoxylem with helical thickened tracheids. The tracheid at right side with bordered pits is in metaxylem. PLY02, slide #C7-6T, X 246. 124. A metaxylem tracheid with scalariform thickening. PLY02, slide #C7-6T, X 246. 125. A tracheid with reticulate thickenings and mixed with somewhat bordered pits. PLY02, slide #C7-6T, X 373.

221 ï I

222 Figs. 126-131. Spinivinea yunguiensis. 126-127. Paratype, cross sections showing wide xylem, hypodermal sclerenchyma ribs, and spine-like structures.

PLY02, slides #A2-P1-1, #Al-l-2-2, X 9.3. 128. Cross section with secondary xylem

(left) and mesarchy primary xylem (right). PLY02, slide #Al-l-2-2, X 177. 129-130.

Cross sections of a stem with trilobe-shaped xylem, wide cortex, hypodermal sclerenchyma ribs, and spine-like appendage (right top corner of Fig. 129). PLY02, slides #A2-3-3-2, #A2-3-3-Pl, X 9.3. 131. Metaxylem showing uniseriate rays and tracheids with multiseriate bordered pits. PLY02, slide # A X 65.

223 224 Figs. 132-137. Vasovinea tianii. 132-133. Holotype. 132. Cross section of stem

with several xylem segments. The basal part of a branching hook structure (H) at

the right lower part. L9407, slide #D-T2, X 15. 133. Cross section of stem showing

central xylem segments, two branch (or hook) traces (b), mesarchy primary xylem

(arrowhead), and a spine-like structure (s) on the right side. L9407, slide #C-B16,

X 15. 134. Paratype. Oblique section of stem with vessel bearing xylem segments and

tendril-Uke structures. The tendril-like structures appear as small protuberances at

their point of attachment to the stem and are seen in the matrix (arrowheads).

PLY04, slide #B, X 7. 135. Left, longitudinal section (above) and cross section

(below) of stem in Figs. 132, 133; Right, an oblique longitudinal section of a

dichotomously branching-hook structure. L9407, slide #C-Bl6, X 2.3. 136. A vessel- bearing stem associated with a leaf of Gigantopteris meganetes with compound mesh venation. PLY03, X 1.4. 137. Insert from Fig. 136 showing the vessels in the stem in oblique section (far left) and the compound round teeth of the leaf (= Fig. 58) in paradermal section (right). Arrowhead pointing at a part of tendril-like structure in the matrix. PLY03, slide #11, X 6.

225 #

226 Figs. 138-144. Vasovinea tianii. 138. Cross-section and longitudinal section showing the large vessels. L9407 slide #C-B16, X 14.8. 139. Longitudinal section showing helical and branching helical thickenings on the protoxylem tracheid (left), and uniseriate (right upper part) and 2-3 rows of scalariform bordered pits (right, arrowhead). PLY03, slide #06, X 185. 140. Longitudinal section of a metaxylem vessel element with multiseriate scalariform perforation plate on its highly inclined, long end wall. PLY04, slide #06, X 185.141. Longitudinal section showing bordered pits on metaxylem tracheids. PLY03, slide #07, X 185. 142. Longitudinal section showing part of a perforation plate (pp) on an oblique end wall with multiseriate pores. PLY03, slide #06, X 185. 143. Oblique longitudinal section. Right upper part and central lower parts are two perforation plates; the right lower part is a normal side wall with bordered pits; the left side shows cross-field of secondary xylem. PLY03, slide #1, X 185. 144. Tangential longitudinal section showing oblique perforation plate connecting two vessel elements. At right lower corner is another smaller perforation plate in face view. PLY02, slide #ClO(l-l), X 39.

227 1

228 Figs. 145-148. Vasovinea tianii. 145. Oblique cross section showing rays (r) and vessels with oblique (above) or almost horizontal (below) perforate end walls.

PLY03, slide #34, X 159. 146 A segment of wood with large vessels. The large vessel is 500 /Am in diameter. PLY02, slide #E-1, X 20. 147. Another section of the specimen of Fig 146 showing vessel elements with oblique end walls (arrows),

PLY02, slide #E, X 37. 148. Higher magnification of a perforation plate from Fig.

147 (right arrow). Note at the right edge, pores are smaller and one pore has some primary cell wall material (arrowhead) which is still present. X 935.

Figs. 149-150. Carpolithus speculatus Mo. 149. A narrow elliptic smooth seed

(arrow), with a flat rim, found on the abaxial side of an actinodromous gigantopterid leaf. Note the pedicle pointing to a secondary vein and an axis with vertical ribs in also associated together (above). LW-25, X 0.8. 150. Carpolithus speculatus Mo.

An elliptic smooth seed on the abaxial side of an actinodromous gigantopterid leaf.

Note the seed with flat rim and pedicle pointing to the basal primary vein of the leaf.

LW-06, X 2.4.

Fig. 151. Two unusual structures (arrows), each with a long stalk attached on a basal primaiy vein which has thicker and longer descending secondaries

(left). On the right side is a another Gigantopteris meganetes leaf. L9448-1, X

2.3.

229 # * g m s

mm

^1* 230 Figs. 152-157. Carpolithus speculatus Mo. Fig. 152. Two ovate smooth seeds

next to a spiny gigantopterid stem (right), LW-05, X 2.3. Fig. 153. Two seeds

(arrows) associated with gigantopterid leaves. L9447, X 1.7. Fig. 154. The counter

part of the seed in Fig. 153. Showing a section of a flat rim (arrow), a sinus

(arrowhead), and the smooth surface of the seed. Note the pedicle pointing at a

secondary vein of a gigantopterid leaf with compound mesh venation in the right

lower corner. X 5.6. Fig. 155. Higher magnification of the seed in Fig. 153 showing

a section of a flat rim (arrow), a sinus (arrowhead), the smooth surface, and a short

pedicle bending into the matrix. L9447, X 5.6. Fig. 156. A carbonized seed with a

section of a flat rim (arrow), a sinus (left upper arrowhead), and the smooth surface

and the pedicle attached to a transection of a gigantopterid leaf with two secondary veins (small arrowheads). L9447, X 6.5. Fig. 157. Higher magnification of basal part of the seed in Fig. 156. The seed pedicle is attached on a secondary vein (S) of a transection of a gigantopterid leaf (L). Note the leaf is compressed into a thin linear shape, but the secondary veins (S) are still recognizable. X 16.8.

231 232 Figs. 158-163. Some permineralized seeds associated with gigantopterids. Fig.

158. Cross section of a seed showing a sinus on the integument and a middle membrane. PLY02, slide #Cl8-103, X 20. Fig. 159. Oblique section of a seed with

a deformed nucellus and an integument consisting of endotesta, sclerotesta, and sacrotesta as well as a smooth epidermis. PLY02, slide #Cl8-103, X 20. Fig. 160.

Longitudinal section of a seed showing the integument composed of only two zones.

LW-02, slide #1. X 20. Fig. 161. Longitudinal section of a small seed with a broken stalk, split integument, and reduced nucellus. PLY02, slide #Cl-2-2. X 48.

Fig. 162. Tangential section parallel with the minor plane of a seed showing the wing-like structure on integument which consists of only two zones (the outer zone is partially decayed). LL-2, X 20. Fig. 163. A seed with wing-like structures similar to that in fig. 162, but the integument is much more decayed and carbonized.

PLY02, X 20.

233 y

159 y : ; : :! S â

1 .

•/./

234 Fig. 164. Three seeds (1-3) similar to Carpolithus speculatus found associated with a compound leaf of Gigantonoclea hallei, from the Upper Permian of Shanxi

Province, Northern China. Specimen No. 1426. X 0.5. The Swedish Museum of

Natural History. Fig. 165. Seeds 1 and 2 of Fig. 164. X 2.5. Fig. 166. Seed 3 of

Fig. 164. X 5.4. Fig. 167. Seed 1 of Fig. 164. X 5.6. Fig. 168. A seed found on the reverse side of the specimen. X 5.6.

235 m irHX.

t

235 Figs. 169-177. Guizhoutheca imnibasis gen. et sp. nov. 171-174, holotype.

169-170, 176-177, paratype. 169. A large synangium located nearby a midrib of a

Gigantonoclea guizhouensis leaf. PLY02, slide #C9(T)-1, X 9.3. 170. Higher magnification of the synangium in Fig. 169. X 47. 171. Oblique cross section of a synangium, cutting through the top level, showing ten empty sporangia around a hollow central area. PLY02, slide #C4(R), X 42. 172. Oblique cross section of a synangium, cutting through the upper middle level, showing two lacunae in the central vascular column and sporangia filled with microspores. Note a gigantopterid leaf on the right. PLY02, slide #C9(L), X 42. 173. Longitudinal section of a synangium. The sporangia flare out and enclose a hollow central area on the top.

The empty base contracts to left side. PLY02, slide #C4-5, X 42. 174. Longitudinal section of a synangium with sporangia on a hollow base. Each sporangium is fulfilled with microspores which are shown in Figs. 179-186. PLY02, slide #C4-4, X 42. 175.

Oblique cross section of a synangium showing with 13 sporangia, some empty and some with palynomorphs. PLY02, slide #C10(L-A), X 45. 176. Longitudinal section of a short synangium showing empty sporangia, central vascular column, and filament-like structures in the hollow base. PLY02, slide #C7(2T-1), X 42. 177.

Close view of filament-like structures in a hollow base of a synangium, longitudinal section. The filament-like structures are beneath the sporangial base (arrow) or extent from the side wall of the synangiate base (W). PLY02, slide #C6, X 172.

237 • ' . . . if ' m y

j

‘ 174

238 Fig. 178. Reconstructed Guizhoutheca imnibasis synangium with a ring of sporangia surrounding a central vascular column on a hollow base, which has some filaments. X 25. Fig. 179. An oblique section of a hollow structure composed of three layers, the dissolved middle (M) layer between the inner (I) and outer (O) layers. Note the smooth inner surface, and some worm-like structures (W) mixed with crystals (C) at one end of the hollow structure. PLY02. X 120. Figs. 180-185.

Microspores extracted from Guizhoutheca imnibasis synangium of Fig. 174. 180.

Poorly preserved microspores. PLY02, slide #C9(L). X 100. 181. A well preserved microspore with a thick wall and a papilla on the wall. PLY02, slide #C4-3, X 2500.

182. A smaller microspore with a furrow-like aperture and a thick wall. PLY02, slide

#C4-3, X 2500. 183. A smaller microspore with a furrow-like aperture. PLY02, slide

#C5(R), X 1000. 184. Broken preserved microspores viewed with SEM. PLY02, X

1000. 185. A microspore with two underdeveloped or reduced sacci. PLY02, slab

C4, X 3000.

239 240 Figs. 186-188. Guizhoutheca? sp. 186. Oblique section of six parallel synangia. Note the lower two synangia (No. 5 and 6) are partially exposed in this section, and each hangs on a secondary vein of a gigantopterid leaf (crosse section; arrows) which has intercoastal lamina folded toward the adaxial side. The top arrow points a tertiary vein of the leaf. PLY02, slab CIO, X 18.7. 187.Another section of the same specimen, as in Fig. 187, prepared with peel technique. Note the synangia

No. 1 and 5 of Fig. 187 are not cut through this section, and the arrow points a tertiary vein of the gigantopterid leaf as the top arrow in Fig. 187. PLY02, slide

#ClO(L-A)-2, X 18.7. 188. Restoration of Figs. 187 and 188 show the lower two synangia hanging on secondary veins (S) of a gigantopterid leaf on the adaxial side.

X 18.7. Fig. 189. A larger gigantopterid leaf with its lower part folded adaxially.

PLY02, slide #C14(T), X 7.5.

241 • . r :•

■ m ' Æ

242 Fig. 190. Cross section of a synangium with five sporangia fused together at the lower part. PLY02, slide #C6(R), X 56. Figs. 191-197. Pecopterid leaves and their synangia as well as spores. 191. Cross section of a pecopterid frond. PLY02, slide #A2-3-4, X 6.5. 192. Higher magnification of a cross section of a pecopterid pinnule in Fig. 191, showing a thick midrib and thick palisade cells. X 63. 193.

Higher magnification of the right side of Fig. 191, showing a C-shaped vascular trace of the rachis. X 20. 194. Oblique cross section of a fertile pecopterid leaf with synangia on the abaxial surface. L9406, slide #2a-2. X 20. 195. Cross section

(upper) and paradermal section of two fertile pecopterid pinnules. L9406, slide #2a-

1. X 20. 196. Some spores in the pecopterid synangia. L9406, slide #2a-2. X 380.

197. Higher magnification of a spore. L9406, slide #2a-2. X 2325.

243 I # m a \ ^

244 Fig. 198. Reconstruction of Gigantonoclea guizhouensis and Spinivinea yunguiensis.

245 I

n

1

Fig. 199. Reconstruction of an actinodromous gigantopterid leaf with a lianar stem Vasovinea tianii, which bears some tendril-like and hook-like structures.

246 Tarim

NCB

Yuxian

SCB

C?

Fig. 200. Late Early Permian, showing the accretion of the Tarim-Qilianshan plate to North China Block (NCB), and the movement of South China Block (SCB) towards the NCB. Jungar (J) and Turpan (T) are part of the Angaran Kingdom to the north (Modified from Yin and Nie [1993] and Wang, D. et al. [1986]).

247 90° N

Angara

60° N

Europe 30° N North NC America /

sc South^ SA America, Africa 30° S ,Sm

India Australia 60° S

Antarctica 90° S

Fig. 201. A new reconstruction of the earliest Permian based upon plant megafossil data. I, Indochina; J, Jungar; K, Kazakhstania; M, Middle Tibet; N, North Tibet; NC, North China; S, South Tibet; SA, Saudi Arabia; SC, South China; Sm, Sibumasu; SP, Spain; T, Tarim; Ty, Turkey; Q, Qilianshan.

248 90 N

Angara

60 N

Europe 30 N North^ ^ V NC A m erica/ /sg:

SC

South SA America Africa 30 S .Sm'

India Australia 60 S

Antarctica 90 S

Fig. 202. A new reconstruction of the late Late Permian based upon plant megafossil data (see Fig. 201 for abbreviations).

249 REFERENCES

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