Two New Species of the Genus Cycadeoidea from the Lower Cretaceous of Utah

Brigham Young University BYU ScholarsArchive

Theses and Dissertations

1975-07-11

Two new species of the genus cycadeoidea from the lower cretaceous of Utah

H. Blaine Furniss Brigham Young University - Provo

Follow this and additional works at: https://scholarsarchive.byu.edu/etd

BYU ScholarsArchive Citation Furniss, H. Blaine, "Two new species of the genus cycadeoidea from the lower cretaceous of Utah" (1975). Theses and Dissertations. 8056. https://scholarsarchive.byu.edu/etd/8056

This Thesis is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. !;!d,- L TWONEW SPECIES OF THE GENUSCYCADEOIDEA f _,I FROMTHE LOWERCRETACEOUS q,,) OF UTAH

A thesis

Presented to the

Department of Botany and Range Science

Brigham Young University

In Partial Fulfillment

of the Requirements for the Degree

Master of Science

H. Blaine Furniss

August, 1975 This thesis, byH. Blaine Furniss, is accepted in its present

.. form by the Department of Botany and Range Science of Brigham Young

University as satisfying the thesis requirement for, the degree of

Master of Science.

ii TABLEOF CONTENTS

LIST OF ILLUSTRATIONS . V ACKNOWLEDGEMENTS. vi INTRODUCTION. . . 1 Location and Collection Site. . 1 Preservation. 3

Stratigraphy of the Cedar Mountain Formation. 4 Age of the Cedar Mountain Formation . 5 Paleoecology. . . . 5 Cycadeoid Origin. . . 7 Comparison of Cycads and Cycadeoids 8

Distribution. 9 Derivation of the Generic Name • . . . 10 MATERIALSAND METHODS .. .. 12 SYSTEMATICPALEOBOTANY. . . . 14 Cycadeoidea medullara •· . 14 Description . . 14 General features . . 14 Stele . . 14 Cortex. . . 16 Leaf bases . 16 Cones • . . 18 Discussion . 24 Comparison with Similar Species . . . . 30 iii Cycadeoidea cleavelandii . . . . . • . 33 Description . . • . . • . . • . . • ...... 33 General features . . • . . . • . 33 Stele ...... 33 Cortex . . . • . . • . . . 34 Leaf bases . . . • . • . . . . • . . 35 Cone ...... 36 Discussion ...... • . . . • . . . . . • • . . • 36 Comparison with Similar Species 38 LITERATURECITED ...... 40 PLATES...... • ...... 44

iv LIST OF ILLUSTRATIONS

Figure Page

1. Index Map of Collection Site . . • •.••• 2

2. Cycadeoidea medullara. L~af Base Vascular Pattern. 17

3. Cycadeoidea cleavelandii. Leaf base Vascular Pattern 17

4. Cycadeoidea medullara. Young Ovulate Cone. • • • . • 20

5. Cycadeoidea medullara. Reconstruction of Bisporangiate Cone • • • . • • • • 21

6. Cycadeoidea medullara. Reconstruction of Cut Away Side and End View of Chambered Synangium • • • • • • • . 23

7. Cycadeoidea medullara. Reconstruction of Longitudinal View of Seed Stalk and Ovuliferous Scale . • • • • • 23

Plate I. Explanation of Plate I ...... 45 II. Explanation of Plate II 47

III. Explanation of Plate III 49 IV. Explanation of Plate IV ...... 51 V. Explanation of Plate V 53 VI. Explanation of Plate VI . . . 55 VII. Explanation of Plate VII ...... 57 VIII. Explanation of Plate VIII • 59

IX. Explanation of Plate IX. 61

X. Explanation of Plate X 63

V ACKNOWLEDGMENTS

I am indebted to Harry and June Cleaveland of Moab, Utah, who were kind enough to donate several specimens from their collection to the Brigham Young University. They also assisted in the discovery and collection of additional material at the collection site.

I also thank Dr. W. D. Tidwell of the Department of Botany and

Range Science of Brigham Young University and members of the conunittee who critically reviewed the manuscript and assisted in the completion of this study. James V. Allen of the College of Biological and Agri- cultural Science was very helpful in the production of plates.

vi INTRODUCTION

The fossil bearing Lower Cretaceous Cedar Mountain Formation near Moab, Utah, U.S.A., has yielded a variety of petrified cycadeoid stems (text fig. 1). This thesis is a report on two species of Cycad- eoidea that were selected for study from among the several stems collected. Fragments of cycadeoid stems have been found from other local- ities in the state, but this,area has yielded the greatest concentra- tion of cycadeoid stems to date.

Harry and June Cleaveland of Moab discovered the collecting site. They donated several trunks to the Brigham Young University and aided the University in the discovery and collection of six additional trunks from the same area. Most of the specimens were found completely eroded from the sandstone. Other trunks, only partially exposed, were recovered by excavation. Further study of the specimens was conducted in the laboratory.

Anatomical investigation was undertaken to determine affinities with previously described genera. Data obtained may reveal specific and phylogenetic relationships among Early Cretaceous cycadeoids.

This study represents the first description of cycadeoid stems from Utah and provides additional information on the diverse floral composition of the Cedar Mountain Formation.

Location and Collecting Site

Specimens were collected from a bluff three miles east of the

1 • 2

CRESCENT JUNCTION

50 6

Highway 160 1 3 miles

Canyon lands • SITE Airfield

UTAH

Grand County enlarged area

1 100 miles

Fig. 1. Index map of collection site. 3

Canyonlands Airfield, NWNEsection 22, T24S, R20E, in Grand.County,

Utah (fig. 8). Upper Jurassic Morrison shales form the sloping sides of the bluff and underlie the more resistant Cedar Mountain sandstone cap (fig. 9)_. Most of the cycadeoid trunks were weathered from the sandstone and were partially or fully exposed on the north and west facing shale slopes amidst talus from the sandstone rim. Three trunks were found still embedded in the sandstone (fig. 10). Several large logs of conifer wood were found associated with the cycadeoids.

Where trunks and wood fragments were abundant, the sediments tended to be pebbly conglomerates rather than sandstone. Since all fossil material had been transported, this indicated the higher energy turbulence present at the time of deposition.

The buff colored Cedar Mountain Formation is a fluvial sandstone. In the general area of the collecting site the texture varies from coarse sandstone with limestone and clay lenses to a pebbly conglomerate. Fresh exposures are light brown to light green. Bedding is irregular. Cementation is weak, but Cedar Mountain strata does not weather as readily as the overlying Cretaceous Mancos Shale or the underlying Jurassic Morrison Formation. Where exposed, Cedar Moun- tain strata forms ridges and ledges on the Morrison.

Preservation

Specimens represented in the collection are silicified petri- factions of monoaxial trunks with attached leaf bases and cones. The exterior of some trunks is often obscured by both sandstone and CaC03 deposits. Weather cracks are severe in some parts of the specimens.

Parts of the cortex and leaf bases have been secondarily replaced 4 with clear quartz. Macroscopically, there is little distortion from

the original shape. Cellular detail is occasionally obliterated and much of the apparent detail fades with magnification.

Stratigraphy of the Cedar Mountain Formation

Originally, the Cedar Mountain Formation was defined as part

of the Jurassic Morrison Formation (Eldridge 1896). When Knowlton

(1920) described Cretaceous age plant remains in the upper portion of

the type section, W. T. Lee who had discovered the plant remains, removed the upper shale and conglomerate units and placed them in the

Dakota Group (Lee 1920). The Morrison Formation was defined as those

continental sediments of Jurassic age only (Baker, Dane, and Reeside

1936).

Stokes (1944) introduced the formation names Buckhorn Conglom-

erate and Cedar Mountain Shale and described these units as lying

between Morrison and Dakota sediments. He later defined the upper

Cedar Mountain Shale and basal Buckhorn Conglomerate as being members

of the Cedar Mountain Formation (Stokes 1952). Similar deposits,

stratigraphically equivalent to the Cedar Mountain Formation in south-

western Colorado, were originally referred to as the Post-McElmo beds

(Coffin 1921). Renamed the Burro Canyon Formation (Stokes and Phoenix

1948), these beds were found by Young (1960) to be physically contin-

uous with Cedar Mountain strata west of the Colorado River and he sug-

gested that since Cedar Mountain was the prior name, these sediments

also be referred to as Cedar Mountain. Cedar Mountain strata are

exposed throughout much of eastern Utah, western Colorado and north-

central New Mexico. 5

Young (1960) divided the Cedar Mountain Formation into upper, middle and lower units. Because of erosion he was unable to directly

trace the Buckhorn from the type area southeast from the San Rafael

Swell, but suggested that a probable correlative of conglomeritic

sandstone existed in the Moab area. He referred to it as the lower

Cedar Mountain-Buckhorn Sandstone, and noted that it becomes more con-

glomeritic towards the San Rafael Swell. The middle Cedar Mountain

Sandstone also becomes more conglomeritic as it approaches the San

Rafael area (Young 1960).

The collecting site is at the northern limit of the lower unit

in central Grand County, Utah. Since the middle Cedar Mountain Sand-

stone is widespread in this area, the plants represented in this study

are probably from the middle Cedar Mountain Sandstone. Neither the upper member of the Cedar Mountain nor the Dakota is present at the

collecting site.

Age of the Cedar Mountain Formation

Collections of non-marine microfossils, plants, and molluscs

by Stokes (1952) indicated that the Cedar Mountain Formation is Early

Cretaceous in age.· Collections by Young(l960) support this conclusion

and he suggests the age as Aptian to early Albian. Fisher (1960) as-

signed the age as Aptian. According to Thayn (1973), the Aptian age

is relatively uncertain.

Paleoecology

Stokes (1952) indicated that the Cedar Mountain strata were

of lacustrine or paludal origin. Young (1960) suggested that during

the Cretaceous, there was a subsidence of the marine basin in central 6

. Colorado, accompanied by an uplift in western Utah. Numerous streams

began carrying large loads of coarse elastics eastward from the up-

,j, .· lifted highlands and depositing these sediments in the lowlands to

form the Cedar Mountain Formation. This is evidenced by coarse con-

glomeritic sediments on the western edge of the formation becoming

finer toward the east. The inland floodplain, thus created, consisted

of streams, ponds, and lakes in which thin limestone beds and clay

lenses were also deposited.

Three different cycles of uplift and deposition produced the

three separate units of the Cedar Mountain Formation. The Middle

Cedar Mountain unit was laid down in the manner described near the end

of the Aptian. As the highlands were eroded, subsequent pulses of

basinal subsidence allowed the overall transgression of the shallow

Mancos sea westward to form the Naturita Sandstone of the Dakota Group

as a beach deposit and the Mancos Shale seaward (Young 1960).

Most workers have agreed that Cedar Mountain deposition occur-

red in an inland floodplain. The presence of channel fills near the

collecting site lends credence to this position. In addition, the

cycadeoids appear to have been deposited near their site of growth.

Cycadeoid trunks consist of a large parenchymatous pith and

cortex with little supportive xylem and with little sclarification in

the leaf bases. They probably were unable to withstand transport for

any great distance. The completeness of the cycadeoid trunks and the

appearance of the leaf bases (length and abundant ramentum) indicates

that abrasion was minimal and that preservation occurred near the site

of growth. 7

The paleoclimate was probably subtropical as evidenced by the lack of well developed growth rings in the woody part of the trunk.

Dicotyledonous angiosperms from the western boundary of the formation also lacked growth rings and their related plant families are tropical in distribution today (Thayn 1973).

Coniferous wood fragments and logs, deposited with the cycadeoids, have annual growth rings. Such woods are capable of being transported greater distances without structural damage, and it is possible they originated in the uplands where the climate was more cyclic.

Cycadeoid Ori_gin

Definite petrified trunks of cycadeoids are first known from the fossil record in the Triassic. The first recognized specimens are advanced in comparison to their suspected ancestors, consequently many researchers advocate a separation from the pteridosperms in the Upper

Carboniferous or Permian. Since no pre-Triassic petrified trunks re- sembling cycadeoids have been found, attempts to postulate a relationship with pteridosperms relies mainly on leaf and reproductive analogy, as has been done by Seward (1917), Wieland (1906), Chamberlain (1935) and others as sited by Delevoryas (1968). The evidence predicts a pre-

Mesozoid origin but plant credentials are necessary to give substance beyond theoretical speculation and these are lacking.

According to Wagner (1964) the primitive characteristics in a related group of plants are those that they have in common. Dele- voryas (1968) attempted to determine what a primitive cycadeoid looked like and what the probable ancestor was. He envisioned a slender, 8 profusely branched stem with many pinnately compound leaves. Micro- sporophylls would contain compound microsporangia similar to members of the Medullosaceae. Ovules would be borne on fleshy receptacle.

He found this feature to'be the most uniform among cycadeoids but the most difficult to trace to a Paleozoic ancestor. The primitive condition described is much the same as is found in the Williamsoniaceae and a telescoping suggested by him would produce the Cycadeoidea type plant. Pteridosperms have the greatest number of structural features that would probably be exhibited by the ancestral type, and although Delevoryas (1968) hesitates to single out a specific ancestor, collectively, pteridosperms exhibit the ancestral condition.

Comparison of Cycads and Cycadeoids

Though there is a strong resemblance between cycads and cycadeoids, their exact relationship is puzzling. Several differences center especially around stomatal characters and reproductive special- ization. Florin (1931) was able t~ differentiate the two groups en- tirely on the basis of the stomates. He confirmed an earlier study by Thomas and Bancroft (1913) who showed that cycadeoids have two guard cells and two subsideary cells which arose from the same mother cell, whereas in cycads, the stomatal mother cell produced guard cells only. Chamberlain (1915) compared reproductive structures between the two groups and pointed out that among other things cycadeoids show greater reduction in the leaflike character of the sporophyll than cycads show in the most reduced living form. Evidence such as this recalls the widely accepted theory that once a character such as the leaflike sporophyll is lost phylogenetically, it would not be re- 9 gained and thus cycadeoids could not have given rise to a group with more extensive sporophylls. Arnold (1953) agreed that whatever their relationship, it was almost certain that cycadeoids did not give rise to the cycads and that, regardless of resemblance, the two groups were probably not closely related below ordinal rank.

The significant differences mentioned above are countered by the similarities and as Wieland (1906) indicated, the vegetative characters between the two fonns have a near analogy. He theorized that the ancestral group was homogenous until the coumon vegetative features became established. Whatever their ancestry, either from common or independant pteridosperm stock, cycads and cycadeoids have persued an independant evolutionary course from the time of their first recognition in the fossil record.

Distribution

Cycadophyte plants were.numerous during the Mesozoic Era and achieved a worldwide distribution. Although the petrified stems of these plants are infrequently found in fossiliferous stratas of this age, leaf impressions, assignable to cycadophyte trunks, are abundant.

Available evidence from the fossil record indicates that cycadeoids reached their greatest numbers during the Jurassic Period and became extinct in the Cretaceous. No undisputed Tertiary cycadeoids have ever been found and it appears that they left no progeny.

Because of their unusual shape, trunks are readily collected when exposed. The first discriptive work was undertaken on cycadeoid trunks in Europe (Mantell 1822). Additional trunks were studied peri- odically as they were discovered and brought to scientific attention. 10

Subsequently, trunks have been found and described nearly worldwide.

Although cycadeoids are not extremely coimnon as fossels, the unusual

shape renders them easily identifiable.

Interest was stimulated in North American species shortly before the turn of the century when three major petrified trunk local-

ities were discovered in the United States. The first was the lower

Cretaceous iron ore beds of the Potomic Formation between Baltimore,

Maryland and Washington, D.C. The second was the Lower Cretaceous rim of the Black Hills of South Dakota, and the third was the Upper Jur-

assic Morrison Formation of the Freezeout Mountains of Carbon County,

Wyoming. Numerous petrified trunks were collected from these sites.

Stems have been found in limited numbers from other areas in North

America, including several states of the United States, Prince Edward

Island in Canada, and Pueble and Oaxaca, Mexico. They have been found

in Triassic, Jurassic and Cretaceous stratas. Stems described in this paper represent the first descriptions of cycadeoid trunks from Utah.

Morphologically similar cycadeoids have been compared in the discus-

sion.

Derivation of the Generic Name

The generic name Cycadeoidea was proposed by Buckland (1827)

for cycadeoid stems and was based mainly on the shape of the trunk and

the character of the armor. Because the shape of the trunk may be

variable, less emphasis has been placed on the constancy of this fea-

ture. Although exceeding the limit suggested by the original descrip-

tion (90cm), columnar forms subsequently have been assigned to this

genus (Ward 1898, 1899; Seward 1897). This is desirable as it is di£- 11 ficult to develop a genus strictly for columnar forms since they must invariably pass through a short juvenile stage. It is justified because, the original description does not exclude taller trunks, it merely states that they are chiefly 30-90 cm.

Many generic synonyms arose for two reasons: diagnostic characteristics were based on features subject to variation, and independ- • ant workers were not aware of, or did not consult the original description. Because of its broad application and priority, Cycad- eoidea has become the accepted generic designation for compact, petrified cycadeoid stems, eliminating many synonyms.

Wieland (1904,1906) found close agreement, except in the seed

(Wieland 1916) between American and European cycadeoids. Descriptions of cycadeoids on the two continents, however, has resulted in a ple- thora of specific names. Fewer workers were originally involved in the naming of American forms, but as with European forms, speciation was based more on salient features rather than histological aspects.

Much of the preliminary cataloging awaited the sound basis of an ex- pected histological search. Unfortunately, the early workers lacked the equipment for such a study, the excitement abated, and most of the stems so avidly collected were never reinvestigated. Although much histological work has been done, a comprehensive, unified study has not emerged, and many suspected specific synonyms still exist. MATERIALS AND METHODS

Because of the fractured nature of the trunks, it was often necessary to embed the specimens in plaster or plastic, or to cement with epoxy prior to cutting to prevent disintegration. The anatomy was revealed by serial sectioning the different plant parts and obser- ving the structure and vascularization.

Transverse sections of the trunks approximately 2.5 cm thick were cut using a 24" rock saw. Material selected for study was reduced from these sections with a 5" rock saw into convenient sizes for sectioning on glass slides. The slides were frosted on one side using a lap wheel and #400 aluminum silica to provide a rough surface for glue attachment. One side of the block to be sectioned was polished, using the lap wheel, and -the.opposite side was marded to iden- tify the working surface and provide identical slide-block placement for serial sections. The blocks were then heated to 150 degrees F. and a thin layer of epoxy was applied to the polished upper surface.

Glass slides were attached by contacting the frosted surface of the slide at an acute angle near the edge and slowly lowering it over the surface of the block. Gentle back and forth movement eliminated air bubbles. After allowing the glue to cure, slides were ·cut using Ward-

Ingram thin section equipment. After sawing, grinding, and polishing, slides were marked and numbered with a diamond tipped pencil for iden- tification.

12 13

A thin coating of Krylon Crystal Clear protective paint was sprayed on slides in place of cover slips to produce clarity. The coating does not scratch easily with normal use and the paint may be removed with xylene. A portion of the bisporangiate cone was coarsly ground with a mortar and pestle and placed in a 34% solution of hydroflouric acid for dissolution in order to examine the pollen. After the silica had disolved, the mixture was centrifuged, decanted and washed with water. The residue was treated with a 5% solution of 'tlaOH for

30 minutes to eliminate extraneous organic matter. The sample was then centrifuged, washed and mounted in glycerine for microscopic examination. This retrieval process is referred to as "pollen analysis" in the discussion.

Anatomical descriptions of specimens w~re made using Zeiss and Bausch and Lomb research microscopes. Slides were studied using both transmitted and reflected light. Photographs were obtained using a Nikon AFMphotomicrographic 'camera mounted on the Zeiss research microscope. No special stai~ing techniques were employed. SYSTEMATICP.ALEOBOTANY

Order CYCADEOIDALES Genus Cycadeoidea, Buckland 1827 Cycadeoidea medullara sp. nov. (Plate II fig. 11, Plate III fig. 16)

Description

General features. The complete trunk with its leaf bases is

123 cm in height and 24.5 cm in greatest diameter at the base. It is unbranched, columnar, and tapers gradually from the base to a rounded

.. ·,. . apex (fig. 11). It consists of a central pith surrounded by a v'ascular cylinder, narrow cortex and the persistant bases of perpendicular, closely appressed, spirally arranged, leaf bases and cones (fig. 15).

Exterior features of the rough trunk, except for occasional protruding cones, are obscure. Short polygonal bracts over the meristem form a small depression in the summit (fig. 14). Lateral compression is slight~

Stele. The large, central pith represents approximately one third the diameter of the stem and leaf bases. This tissue consists of loosely arranged parenchyma cells with prominent intercellular spaces and scattered secretory idioblasts (fig. 44). Parenchyma cells have a rounded, polyhedral shape and vary from 60-220 um in diameter.

Mucilage cavities in the pith may be several cells wide and up to 300 um in diameter. At the periphery of the pith, a medullary sheath of tightly arranged, axially elongate parenchyma cells, contours the

14 15 interior of the xylem. These cells slope uni£ormly outward at an oblique angle toward the xylem and represent a prominent band 1-3 nm wide (figs. 41, 43). The transition from loosely arr.anged interior pith to the medullary sheath is abrupt. A few tracheids appear to be isolated within the sheath.

The vascular tissue differentiated as a eustele and consists of collateral bundles, separated by leaf gaps (fig. 27). Cambial secondary growth has enlarged the radial width of the vascular tissue to 14 mm near the base of the stem. Xylem comprises roughly two thirds of this tissue (fig. 21).

Primary xylem forms radiating wedge-shaped strands one to several cells wide that extend from the pith and join directly into the secondary xylem (fig. 47). These strands are separated by rays which are occasionally broad and lenticular (figs. 4~, 47). Individual tracheids are 12-24 um in diameter and are rounded in transverse section.

Walls are 4-7 um thick and they exhibit reticulate to scalariform secondary thickenings. Transition to secondary xylem·is gradual.

In the secondary xylem, tracheids are radially rectangular in

transverse section and range from 15-90 um by 12-54 um in size (fig.

51). Walls are 6-12 um thick. Older cells, although basically rectangular, often have lobed walls. Radial walls exhibit uniseriate scalar-

iform pits with broad elliptical aperatures (fig. 49). There are in-

tegradations of occasional.alternate biseriate pitting. Similar pit-

ting occurs on the tangential walls. Growth layers in the xylem are

slightly evident.

Three types of rays are represented. Broad lenticular rays are

associated with the primary xylem. Uniseriate to rarely triseriate 16 medullary rays separate raqial xylem plates 1-3 cells wide, and larger medullary rays are associated with leaf gaps.

Cells in the cambial zone are not preserved (figs. 50, 51).

Phloem tissue has a radial width of 3-5 mn in older parts of the stem but preservation is poor. Cells in the phloem average from 15-30 um in diameter. Fibers with diameters as high as 63 µm and walls to 18 µm thick occur both in the phloem and occasionally in short radiating pericyclic strands at its periphery (fig. 52). Cambial growth is evidenced by the regularity of the secondary vascular tissue.

Cortex. The cortex is from 3-5 mn broad and is bounded by tabular epidermal cells. It contains many secretory sacs and is trav- ersed by numerous spirally arranged vascular traces. Departing traces first appear as radial bulges protruding into the cortex accompanied by an extension of the pith into the xylem. They gradually expand radially until a bulky C shaped trace has become separated from the vascular cylinder. As it emerges through the cortex it separates into a number of smaller segments, arranged in an O shape (fig. 21). The leaf gap closes before the departing bundle begins to segment. Traces traverse the cortex on a gradual incline for 3-4 cm, then upon segmentation, depart obliquely. Some dividing and anastomosing of vascular strands occurs before they enter the leaves. The same trace that supplies the cone also appears to supply the subtending leaf.

Leaf bases. Ramentum obscures the shape and position of the leaf bases. Transverse sections show.that petioles vary from triangu- lar to rhomboidal but distortion creates a lack of uniformity of shape 17

•• • • • • • • • • • • • ••• • • • • •• • •

Fig. 2. Cycadeoidea medullara. Leaf base vascular pattern, (SX) •

•• • • • •• •• , •

Fig. 3. Cycadeoidea cleavelandii. Leaf base vascular pattern, (4X). 18

(text fig. 2; fig. 13). Petioles may reach heights of 15 mm and widths of 25 mm. Leaf base length is 6-7 cm.

The interior of the petioles consists of loosely arranged parenchyma cells that vary from 24-186 µmin diameter. Numerous mucilage cavities varying in size from 75-396 µmare scattered throughout. The vascular supply consists of an enclosing system of bundles arranged parallel to the margin except at the upper angle where it forms a deep, rounded, ventral trough. The arrangement of vascular tissue is incon- sistant in distorted petioles. Sclerification of the petiole is minimal. The epidermis consists of tabular·cells, arranged somewhat in rows, and syndetocheilic stomata (figs. 37, 39, 40).

Long ramental scales arise from the petioles. They are fusiform in transverse shape and consist of several cells arranged in uniseriate fashion (fig. 38). Larger cells reach maximum diameters of 40-

75 pm. Scales from the adjacent petioles form a ramentious wall 1-9 mm thick but a commissural line is not uniformly apparent.

Cones. Numerous cones are borne laterally on the trunk in leaf axils. They consist of approximately 30 concentrically arranged bracts on an axis or peduncle that terminates in a conical receptacle. Vascu- larization of the axis consists of an almost completely enclosing siphonostele at the base of the peduncle that becomes divided distally into a eustelic arrangement. Vascularized bracts, extend toward and beyond the receptacle. They may vary in transverse shape, as do leaf bases, b~r are basically rhomboidal with rounded obtuse angles and may reach 3.5 X 7 mm in diameter (fig. 12). They develop profuse amounts of long, hairlike ramental scales which extend beyond the receptacle to 19

encase it (fig. 35). Ramental scales on the bracts are similar to

those on the leaf bases but smaller. Two types of cones appear to be present.

Young ovulate cones, found at the top of the trunk, have peduncles less than 1 cm in length; receptacles are about 15 mm long and

6-8 mmwide at the base. The receptacle is .covered with blunt, clavi-

form seed stalks and interseminal scales which may vary in length from

.5-1.5 mm. The longest are those nearest the tip. The inflated ends are 145-295 umin diameter. Individual seed stalks with immature ovules are usually flanked by a 4-6 interseminal scales. Cones are rounded in cross section and about 2-2.5 cm in diameter. There are no visable microsporophylls (text fig. 3; fig. 17).

Receptacles of older ovulate cones found lower on the trunk have increased in size by nearly one third and the peduncle has elongated to extend them beyond the leaf bases (figs. 23, 25). Because they were unprotected, the terminal portion of most of these cones has been abraded and the nature of the mature cones and seeds cannot be determined.

Near the top of the trunk, but below the young ovulate cones, a bisporangiate cone was found. The peduncle has elongated and the cone tip is exposed beyond the leaf bases (fig. 27). The receptacle is similar to thos~ on the ovulate cones but appears more dome shaped. Seed stalks and interseminal scales at the base of the receptacle are just over 1mm.long. The blunt tips are 124-235 um wide and they are similar in shape to those on the ovulate cone. Integuments of the ovules appear to be flared distally to form a V shaped micropyle that narrows toward a dome of nucellar tissue (text fig. 7). Preservation of the 20

...... ·.. : ...... \\...·. .. · ...... ·: . ... .: .... :-.. ·.·· ·.:.· :_: :: . ... . ·..: ...... : ...... ·.•...... _.).-·>/-::\:.:·...... : . .. ..

Fig. 4. Cycadeoidea medullara. Young ovulate cone, (8X). 21

......

...... •...... · . .. .: ...... ·...... :.·.·.·:• .·. . •· ...... • ......

Fig. S. Cycadeoidea medullara. Reconstruction of bisporangiate cone, (7X). 22 apex of the receptacle is poor but the seed stalks and interseminal

scales are shorter (less than .6 mm) and less claviform. The receptacle is flanked by microsporophylls that emerge from the peduncle at the base of the receptacle. They form a massive dome of tissue that, including the receptacle, is nearly 2 cm in diameter (text fig. 5).

Microsporophylls contain chambered synangia distally which are

1 mm in width and up to 4 nun in length (figs. 30, 31, 32). They are

reniform but so tightly packed that shape varies. Synangial walls vary

from 36-84 um in width and are composed of radially elongate, thick walled cells. Longitudinal chambers, containing microspores, extend

the depth of the synangium (fig. 6a). Synangia are usually not more

than two chambers wide but are several (6-20) chambers in length (fig.

6b). Chambers are 75-500 um wide and are separated by partitious 25 um

thick. Microspores are elliptical, about 25-35 um wide and 30-68 um

long (figs. 28, 29). The development of the milcrospores indicates that

the male portion of the cone was approaching maturity.

Two abscission layers have developed completely across the peduncle of extended ovulate cones (figs. 22, 25). The outer layer may be up to 1 nm in width and is formed just below the last whorl of bracts,

8-10 mm from the base of the receptacle. Separation probably occurs

at this point. The second layer is about one half the width of the

outer layer and the two layers are 2-3 mm apart. An abscission layer has not formed on the extended bisporangiate cone. Expansion of cones during their development has caused severe

distortion to surrounding leaf bases (figs. 19, 20). Immature cones

elongated and, accompanied by bract development, extended the receptacle

near or past the periphery of the leaf bases. In many of the presumably 23

Fig. 6. Cycadeoidea medullara. Reconstruction of cut away side (a) and end view (b) of chambered synangium, (25X).

...... -::': .:

Fig. 7. Cycadeoidea medullara. Reconstruction of longitudinal view of seed stalk (left) and ovuliferous scale (right), (llOX). 24 mature cones, the receptacle has been shed from the plant and the remaining bracts form a cone socket (fig. 26).

REpository: Brigham Young University, Department of Geology,

2270 (holotype); 2271 (Paratype).

Locality: Three miles East of Canyonlands Airfield, Utah.

Horizon: Cedar Mountain Formation.

Age: Lower Cretaceous

Discussion

Two trunks of Cycadeoidea medullara were studied. One trunk was complete and is designated the holotype. The other trunk is designated a paratype. The paratype is 67 cm long and 27 cm in diameter

(fig. 16). The base of this trunk was not recovered, but the size indicates a larger and taller habit than is exhibited by the holotype.

Mucilage cavities in the pith have unusual cell-like glQbular structures near th~ir walls which represent either cells or secretory material (fig. 45). Interestingly, secretory idioblasts are connnon in all parenchymatous tissues except the medullary sheath. The sheath is easily recognized and is an aid in macroscopic determination of this species. The specific name medullara was named for this feature.

Secondary growth has occurred but the woody column is thin.

This is unusual as most tall trunks have substantial amounts of wood.

The exact reason for the subdivision into growth rings is not clear.

A cuticle pattern approximating the regular outline of epidermal cells was retrieved from the masceration process of pollen analysis.

Rather than a uniform surface coating, it appears as ropelike bands 25

along cell margins~ interconnecting strands spaced between them.

(fig. 36).

No young, unexpanded leaves are present. They may have had a seasonal appearance; therefore would be found preemergent only at cer-

tain times of the year. Leaf base distortion appears to be the direct result of fructification. Very little sclerenchyma is present in the leaf bases, suggesting that they were suc~ulent and, therefore, suscep- tible to being crushed by the pressure of the expanding strobili. Un-

disturbed leaf bases exhibit the marginal bundle pattern with ventral

trough, characteristic of cycadeoids, but btm.dle patterns vary consid- erably in distorted petioles. Scale leaves could have been numerous on

the trunk, but they are identificable only at the apex (fig. 14). Dis- articulation of leaves and cones has formed a relatively uneven surface on the trunk. Many cones are not visible on the surface of the trunk.

Sh~elded by armor and ramentum, they are only found by sectioning.

They are distributed spirally rather than scattered or in clumps (fig. 20). Cones probably first formed as young primorida. Receptacles developed and were subsequently extended by elongation of the originally short, blocky peduncles. Bract development probablly occured simultan- eously (figs. 17, 23). Interpretation of the maturation process was based on cones in which the peduncle had elongated, but the receptacle had not changed shape other than to increase in size. Developing young

cones near the top of the trunk suggest progressive maturation.

Abscissed lower cones had apparently matured, indicating that the trunk

is not monocarpic. Seed stalks and interseminal scales are short in immature cones. 26

Preservation makes it difficult to distinguish between them in longitudinal section (fig. 34). Potential seeds are identified in cross section by a differentiation in nucellar and integumentary tissue; whereas ovuliferous scales are homogenous (figs. 33, 46). Mature seeds were not folmd, but it is probable that during maturation the seeds enlarged and seed stalks and interseminal scales increased in length. The bisporangiate cone was found just below young ovulate cones near the summit (fig. 27). Because of poor preservation, the nature of other large cones in the vicinity were indeterminable. Since only one bisporangiate cone was found it is likely that microsporophylls disin- tegrated soon after shedding their pollen.

It has been suggested by Crepet (1972) that most cycadeoid cones were bisporangiate. The assumption has been that the staminate portion of the cone matured, shed·pollen, then disinte~rated prior to seed maturation. Evidence for this in Cycadeoidea medullara is the presence of a bisporangiate cone. In addition, there is an annular shoulder at the base of the receptacle of older ovulate cones that may represent the attachment point for microsporophylls (fig. 22). Other than this, however, there is no evidence of their existence. All the cones may have been bisporangiate, but there appears to be a trend toward the monoecious condition.

The difficulty in understanding the exact nature of the fructi- fications is that the bisporangiate ontogeny is not com~letely under- stood. The young cones found at the top of the trunk and above the bisporangiate cone do not appear to have male parts. They may have developed microsporophylls later, but this would be unusual.

There is some foreign material adjacent to the receptacle in one 27

young ovulate cone (fig. 17), but it is not continuous around the re-

ceptacle, nor is there the appearance of an attachment point from which

it would have developed. The amount of this material is small, it does

not resemble synangial walls, nor are there any identifiable remnants

of pollen. If it represents microsporophylls, they are extremely re-

duced and bear no resemblance to those on the bisporangiate cone. In other young cones, even where the receptacle and enclosing bracts are well preserved, no distinct male tissue can be found. Significantly,

there is little relationship between the amount of this material and

the amount of tissue produced by the microsporophylls of the bisporan-

giate cone (compare text figs. 4 and 5).

Young ovulate cones were still tightly enclosed by the ramentmn and leaf bases of the armor so it is unlikely that microsporophylls would already be disintegrating at this early stage (figs. 14, 17). The possibility that pollen could have been effectively disseminated while the cone was still enclosed is remote. If the cones were bisporangiate and self-fertilized, this would not be a problem, but the

bisporangiate cone apparently was thrust beyond the armor for the possible function of cross pollination (fig. 27).

It is possible that Cycadeoidea medullara demonstrates phylo-

genetic development towardsa monoecious habit. The monoecious condition would have been derived from the bisporangiate cone by a phylogenetic

loss of male parts from female cones and corresponding loss of female parts from ma.le cones. The material found in the young ovulate cone could represent vestigial microsporophylls. Considering this, it is reasonable to find an annular shoulder for microsporophyll attachment on the older ovulate cones. The seed stalks and interseminal scales of 28 the bisporangiate cone may represent the vestigial fertile zone of the female. If this is true, then the two types of-cones represented are distinctly male and female.

If the plant was monoecious, self fertilization as proposed If by Delevorays (1968) does not answer the pollination question. There is evidence of insect visitation, as furthe! discussion will show, but it is more likely that Cycadeoidea medullara was wind pollinated. The nature of the trunk would have been of some assistance, giving a height advantage. According to Crepet (1972), 30 um is usually considered the upper size limit for windblown pollen. Erdtman (1957), however, cites several gymnosperm species with pollen that exceed this width by more than twice. It appears then, that f.. medullara pollen is within the size range for effective wind transport. Additionally, the pollen is smaller than the pollen of Ephedra, which is windblown, and the two pollens have a somewhat similar shape.

Microspores visible in thin sections of the bisporangiate cone were elliptical and appeared to be mature (fig. 28). Microspores retTieved by pollen analysis, however, showed many young stages • Some even appear to be attached in tetrads. Due to presumed immaturity, size and shape is somewhat irregular and no peculiar identity marks were found. These microspores are predominantly smaller than those visible in the thin section slides and they are less elliptical (fig.

29). Since the pollen had not yet been shed from the cone, immature stages would be suspected.

Animal disturbance, by chewing insects has apparently occurred in the bisporangiate cone. They have excavated a tunnel 4.5 mm in diameter. It is evident as a distinct boundary between undisturbed 29

tissue and that replaced by frass (fig. 24). Several cones, possibly

representing those with male tissues, have been similarly disrupted.

The effect has been to obliterate the structure of these cones.

As Chamberlain (1935) pointed out, many living cycads are

reported to have been insect pollinated. According to his studies, however, they are overwhelmingly wind pollinated. He has observed

that, although insects doubtless feed on ~he pollen and may be abundant on the male cone, they rarely visit the female cone. Therefore, pollination of cycads by insects, with the possible exception of Encephalartos

(Rattray 1913), would be more accidental than necessary or evolved.

Quite possibly this was the case with the cycadeoids.

Ovulate cones at.the top of the trunk were tightly encased by bracts and ramentum. Elongation of the peduncle then forced the recep-

tacle beyond the leaf bases. Several cones were found in this stage or process of maturation. No completely mature cones were found because

they were obviously shed from the plant at maturity. The numerous empty cone socket.s found on the trunk attest to this.

The exact ontogenetic development of bisporangiate cones is unclear; yet if they were the male counterparts of ovulate cones, they were undoubtedly extended beyond the armor at maturity for pollen re-

lease. Even though owlate receptacles may not have been completely

exposed at maturity, the presence of other windblown pollen types;

recovered during pollen analysis, indicates that the ramentum was

certainly not an impenetrable barrier.

Contrary to what Crepet (1972) believed, peduncles, in at least

some species of Cycadeoidea, were capable of extending cones beyond

the armor for pollination. Air currents would have had access to the 30 pollen and the pollen was within the size range for wind transport.

Bracts of extended owlate cones appear to have expanded away from the receptacle, placing owles in a receptive position for pollination.

If f.. medullara was monoecious, outcrossing was unavoidable. Out- crossing probably occurred by anemophily, although emtomophily may have accidentally occurred. Even if all co~es were bisporangiate and selfing was the primary source of pollination, some outcrossing by the above agencies is still probable.

When discovered, the holotype was still partially embedded in talus rubble. Although a root system was lacking, the basal portion appeared to be trinacriform, suggesting a taproot system that was divided into three parts.

Comparison with Similar Species

Of the North American forms, Cycadeoidea medullara most resembles the Piedmont Black Hawk trunks from the Black Hills of South

Dakota. Ward (1898, 1899) originally catalogued these into a number of species. When Wieland (1916) reexamined this collection, he determined that only five species were defensible. These and other closely associated North American types are compared with C. medullara in the following paragraphs. In leaf base vascular configuration, Cycadeoidea stilwelli and

C. cicatricula are similar to f.• medullara in that bundles are marginally alligned, whereas inf.. jennyana, C. ingens, and C. formosa bundles are distributed throughout the petiole.

Cycadeoidea cicatricula is a short trunk. Leaf bases are rhombic, smooth and symmetrical while in C. medullara they are irregu- 31 lar and uneven. Leaf bases are only half the size of the Utah cycadeoid. f_. cicatricula is noted for a general absence of fructifica- tions and there is a corresponding lack of distrubance to the leaf bases, whereas f.. medullara is just the opposite. The armor is only half as wide as in C. medullara; yet cortex and wood widths are several times wider.

Cycadeoidea stilwelli resembles f.._medullara in habit but is a branched form with regularly arranged rhombic leaf bases. There are few reproductive structures, but even where present, they do not tend to disorganize the regularity of the leaf base spirals. Wood and cortical zones are broader.

Cycadeoidea formosa resembles C. medullara but is a short conical form with regularly arranged, undisturbed leaf base spirals.

The cortex is three times wider, the wood zone four times wider (with two distinct rings) than C. medullara.

The three species noted above are small forms that are dwarfed by the two remaining large columnar Black Hawk types, Cycadeoidea jennyana and f. ingens. Although similar in height, f • medullara is not nearly as wide as these.

Cycadeoidea jennyana has a somewhat disorganized leaf base pattem but distortion is not severe. Ramentaceous walls between leaf bases are three to four times as wide as c. medullara. The most out- standing histological differences are in the cortex, wood and pith regions where widths are substantially greater. Although Wieland (1916) suggested that f. jennyana appeared to approach the monoecious .. condition, he was probably incorrectly interpreting a developmental stage of the bisporangiate cone in which the androecium had disinte- 32 grated. Cycadeoidea ingens is larger than f.. jennyana and has huge leaf bases even in young trunks. Yale trunk number 642, tentatively assigned to f.. ingens has a similar leaf base pattern to C. medullara, but it is significantly different from other large-leafed Black Hawk forms which otherwise tended toward a disorganized type of bundle pattem. Overall, in size and in amounts of cortex and wood, f.. ingens does not compare well with f_. medullara. It also appeared to

Wieland (1916) to approach the monoecious condition.

In comparison with other North American columnar types, the

Maryland cycadeoids differ from Cycadeoidea medullara both in their histology and short robust habit. C. beecheriana and f_. wyomingensis, the two short columnar Wyoming types, are also histologically dissimilar. The South Dakota, Minnekahta, types are .robust, much branched types and except for C. excelsa which resembles f.. jennyana, they are distinctly different species. C. excelsa is similar in habit . -, only. f.. stantoni from California, f_. dartoni from South Dakota, and C. nigra from Colorado are all column~r but differ in that they are monocarpic and have a fructification in each leaf axil. C. mirabilis, also from Colorado, is columnar but differs in leaf base characters. 33

Genus Cycadeoidea Buckland 1827 ~ycadeoidea cleavelandii sp. nov. (Plate IX fig. 53)

Description

General features. The specimen consists of the columnar, unbranched, central portion of a trunk (fi~. 53). It is 22 cm long and not noticeably tapered. It ·is obovoid, and 12-16.5 cm in diameter

(fig. 54). Typical cycadeoid stem and leaf base features are exhibited.

Stele. The large pith is 4.5-5.5 cm wide. It consists of polyhedral parenchyma cells that vary from 40-170 cm in diameter (fig.

56). The larger cells are centrifugally arranged. Cells may be axially elongated, to twice their diameter, and all cells are elongated in the vicinity of large rays associated with leaf traces. Small

intercellular spaces are evident. Mucilage cavities up to 200 JlDl in diameter are present in the pith. They contain dark brown globular

structures probably of secretory origin.

The vascular tissue originated as a eustele. Secondary growth has formed a cylinder of vascular tissue, individual segments of which are separated by leaf gaps. Xylem comprises the inner two-thirds of

the radial width of these wedges (fig. 55).

In transverse section, endarch primary xylem forms strands one

cell wide, becoming two or three cells wide that wedge and join the

secondary xylem (fig. 63). Primary xylem cells are rounded in cross

section, 12-27 um in diameter and have thick walls and small lmnens. 34

Rays one to several cells wide extend from the pith and separate the primary xylem strands. Radial rows of secondary xylem are separated by uniseriate or occasionally biseriate medullary rays (fig.

59). Medullary rays in the leaf gaps are multiseriate.

Some secondary tracheids are polyhedral in transverse section, but most are square to rectangular (fig. 60) Tracheids show scalariform pits, some with large elliptical aperatures (fig. 61). Diameters of these cells range from 30-75 µm and walls are 3-6 µm thick. Cambial growth is evident from the regular arrangement of vascular tissue.

Growth rings are not present.

The cambial zone is 2-5 cells wide. Cambial initials approx- imate the size of the cells they produce-with the exception that ray initials become greatly enlarged in the phloem. Phloem cells range from 10-30 µmin diameter and form radiating strands separated by the enlarged ray cells. Numerous fibers in the phloem occur both scattered and in tangential bands (fig. 62). Fibers are orbicular, 12-36 µm wide, and have walls up to 6 µm thick. Large parenchyma cells occur at the periphery of the pholem but a distinct endodermis is not apparent.

Cortex. The cortex is narrow. Leaf bases begin 1-7 nnn from the periphery of the phloem (fig. 57). The cortex is composed of parenchyma cells, randomly distributed idioblasts, and vascular traces.

Parenchyma cells are thin-walled and usually 35-70 µmin diameter, although some, associated with the vascular traces, are exceptionally large, and reach 160 µmin diameter. Mucilage canals with diameters of

75 µm and upward and abundant. Larger canals approach 275 µmin diameter. They consist of a central cavity lined with parenchyma cells and 35 often contain residual secretory material which has contributed to the coloration of surrounding cells. •

Spirally arranged leaf traces leave the stele and traverse the cortex. They are first identified as narrow radial bulges in the vascular tissue, arising at the lower angle of each large ray. Ray paren- cb:yma cells accompany the trace and reach 273 Jlill in length. The bulge increases in size outwardly until two adjacent crescent shaped segments can be clearly seen departing from the vascular cylinder (fig. 55).

They emerge obliquely through the cortex, separate into a number of segments (usually 5) and increase in size. At the point of trace segmentation, the large leaf gap disappears as the wedges of xylem in the vascular cylinder anastomose. The segmented bundles are arranged in a

U or O shape with the primary xylem oriented toward the inside. They then pass outward into the petiole.

Leaf bases. Leaf bases occur in a regular spiral. They are kire-shaped in transverse section, and reach maximum heights and widths of about 3 cm.

Petioles produce and are surrounded by uniseriate ramental scales. Transversly fusiform, central cells of the scales may be 32-65

JJm in diameter with walls 8 µm thick (fig. 58). Scales emerge in a thick mat from the epidermis of the petiole. Numerous mucilage canals similar to those in the cortex occur in the interior of the petiole.

The imbedding tissue consists of parenchyma. cells 48-144 Jlill in diameter.

The vascular supply of the petiole is a loosely enclosed system of collateral bundles with a deep, narrow trough on the ventral side (text fig. 3). Sclerification of the petiole is minimal. 36

Cone. The peduncle of the only cone occurs among the longer petiole bases, and it is 1 cm in diameter. The vascular tissue is represented by a siphonostele of collateral bundles. The peduncle is surrounded by spirally arranged bracts, but there is no trace of either male or female parts. Surrounding petioles are not greatly distorted, and no other peduncles are evident.

Repository: Brigham Young University, Department of Geology,

2272 (Holotype).

Locality: Three miles East of Canyonlands Airfield, Utah.

Horizon: Cedar Mountain Formation.

Age: Lower Cretaceous.

Discussion

Cycadeoidea cleavelandii was donated to the Brigham Young

University by Harry and June Cleaveland. Original interest cente.red around the possibility that it may have been allied to the William- sonaceae family because it appeared to be branched and also appeared to lack cones. In studying the specimen, it was found to be unbranched and, although a complete cone was not found, a peduncle was discovered.

Cycadeoidean characters became clearly established, and it was named after the contributors.

The pith is homogenous throughout, with the exception that larger parenchyma cells occur centrifugally. They parallel a narrow zone of unidentifiable tissue just inside the primary xylem. Many small bodies possibly representing nuclei or storage products are present in the parenchyma cells. Mucilage sacs in the pith are lined with epithe- lial cells. 37

The cortex is narrow and the exact nature of the vascularization of the leaves and cones was not detenninable. It appeared that secondary growth increased the size of the traces after they had departed from the vascular cylinder. Some exceptionally large traces may represent anastomosed traces that supply cones. Most cycadeoid leaf traces are U-shaped as they leave the vascular cylinder. Cycadeoidea cleavelandii is of interest because lea£ traces are formed by two crescent shaped halves.

Leaf bases are large. They have a regular arrangement and their shape is uniform. Abrasion appears to have reduced the normal abscissional distance of the leaf bases. The effect has been to clarify exterior features, and there is no ramentum to obscure the surface of the trunk. Several of the leaf bases examined appeared to lack vascular tissue. Although there is no appreciable difference in size between these and vascularized leaf bases, they may represent scale leaves.

Little could be determined about reproductive structures. Only one peduncle was found, so cones were judged to be infrequent. The peduncle is large and rounded in cross section. It had apparently elongated to extend the receptacle beyond the leaf bases. The fructifica~ tion either remained pendant or was shed from the plant at this time.

·cycadeoidea cleavelandii has a columnar trunk, but the exact height was not determined. Since there is little taper, it is assumed to have been tall in respect to the width. One side of the trunk had been compressed. However, it appeared that this was a feature of growth rather than of preservation, and suggests the possibility that£.:. cleavelandii may have grown clumped. 38 Comparison with Similar Species

The columnar habit of Cycadeoidea cleavelandii recalls the

Piedmont Black Hawk types of South Dakota. The Mi.nnekahta trunks, also

from the Black Hills, consist mainly of gigantic, branched forms.

Whereas£.:. cleavelandii is columnar, it is neither branched nor massive.

In size,£.:_ cleavelandii most resembles the fiedmont types£.:_ stilwelli

and£..:_ cicatricula. It is smaller than£.:_ jennyana, £.:_ ingens and.....£..:_ formosa. Since reproductive morphology cannot be compared, reliance for

speciation is based solely on vegetative characters. Precise compari-

sons are limited to gross morphological features.

Cycadeoidea jennyana,...£.:. ingens and£.:_ formosa have large leaf

bases comparable in size to£.:_ cleavelandii but they are dissimilar iri

their bundle patterns. It is unlikely that secondary growth would have

increased the size of the vascular cylinder of£.:_ cleavelandii to widths

comparable to these three large Black Hawk types. Also, the vascular

traces in the cortex are U-shaped and massive compared with£.:_ cleave-

landii. £.:. formosa has the narrowest cortex of the three but is dissimilar otherwise.

In size, Cycadeoidea cleavelandii resembles£.:. cicatricula.

Leaf base bundle patterns of£.:_ cicatricula are marginally alligned but

leaf base widths are about one third the size of£:. cleavelandii. Wood

and cortical widths are twice those of£.:_ cleavelandii. Other than size

there is little resemblance between these two species.

Cycadeoidea cleavelandii is somewhat similar to C. stilwelli in size. Leaf bases of£:. stilwelli are larger than C. cicatricula but

still smaller than those of C. cleavelandii. Bundle patterns are mar-

ginally alligned but bundles are arranged in two spiral rows~ dissimilar 39 to£.:_ cleavelandii. £.:_ stilwelli exceeds£.:.. cleavelandii by 10 cm in overall width, making pith, vascular and cortical widths substantially greater.

In comparison with Cycadeoidea medullara, there are several distinct differences. Vascular traces in the cortex form two crescents in

cleavelandii while they are initially U-shaped in~ medullara.

Leaf bases have been deformed by the numerous fruits produced in the latter whereas they are undisturbed in the relatively unfructified £.:_ cleavelandii. Size and shape of the leaf bases vary as do vascular bundle patterns. Additionally, there are no large rays found in asso- ciation with the primary xylem nor is there a sheath of medullary pith in£.:. cleavelandii. Although they are somewhat similar in columnar habit and size, they thus differ in histological detail. £.:. cleavelandii does not compare well with other North American types. Before more precise conclusions of similarity can be drawn, histological de- tails must become available from other type specimens. LITERATURECITED

40 LITERATURECITED

Arnold, c. A. 1953. Origin and relationships of the cycads. Phyto- morph., 3:51-65.

Baker, A. A., C.H. Dane and J.B. Reeside 1936. Correlation of the Jurassic formations of parts of Utah, Arizona, New Mexico, and Colorado. U.S.G.S. Prof. paper 183, 1-66.

Buckland, W. 1827. Session of June 6, 1827. Proc. Geol. Soc., London, 1 (8):80-81.

Chamberlain, C. J. 1915. The living cycads. Univ. Chicago Press, 141-168.

____ • C. J. 1935. Gymnosperms: Structure and evolution. Univ. Chicago Press, 41-164.

Coffin, R. C. 1921. Radium, uranium and vanadium deposits of south- western Colorado. Colo. Geol. Surv. Bull., 16:1-223.

Crepet, W. L. 1972. Investigations of North American cycadeoids: Pollination mechanisms in Cycadeoidea. Am. J. Bot., 59· (10): 1048-1056.

Delevoryas, T. 1968a. Some aspects of cycadeoid evolution. J. Linn. Soc. (Bot.), 61:137-146 •

• T. 1968b. Investigations of North American cycads: Struc- ---- ture, ontogeny and phylogenetic considerations of cones of Cycadeoidea. Palaeontog., 121:122-133.

Eldridge, G. H. and S. F. Emmons 1896. Geology of the Denver Basin in Colorado. U.S.G.S. Mon., 27:1-556.

Erdtman, G. 1957. Pollen and spore morphology/Plant taxonomy. New York: The Ronald Press Co., 1-147.

Fisher, D. J., C. E. Erdmann and J.B. Reeside 1960. Cretaceous and Tertiary formations of the Book Cliffs, Carbon, Emery, and Grand Counties, Utah and Garfield and Mesa Counties, Colorado. u.s.G.S. Prof. paper 332. 1-80.

Florin, R. 1931. Untersuchungen zur stammgeschichte der coniferales und cordaitales. Kungl. Svenska Vetenskapsakad. Handl. 3.

41 42

Knowlton, F. H. 1920. A dicotyledonous flora in the type section of the Morrison Formation. Am. J. Sci., 4th ser., 49:189-194. Lee, W. T. 1920. Type section of the Morrison Formation. Am. J. Sci., 4th ser., 49:183-188.

Mantell, 1822. Geology of Sussex. The Fossils of the South Downs. 42-43. Cited by Wieland, G. R. 1906. American fossil cycads Carnegie Inst. Wash., Publ. 34 :14.

Rattray, G. 1913. Notes on the pollination of some South African cycads. Trans. Roy. Soc. South Africa, 3:259-270.

Seward, A. C. 1897. On Cycadeoidea gigantea, a new stem from the Purbeck Beds of Portland. Quart. J. Geol. Soc. London, 53: 22-39. ____ • A. C. 1917. Fossil plants. Cambridge Univ. Press, 3.

Stokes, W. L. 1944. Morrison and related deposits in and adjacent to the Colorado Plateau. Geol. Soc. Amer. Bull., 55:951-992.

______• W. L., and D. A. Phoenix 1948. Geology of the Engas-Gypsum Valley area, San Miguel and Montrose Counties, Colorado. U.S.G.S. Prelim. Map 93, Oil and Gas Inv. Ser.

____ • W. L. 1952. Lower Cretaceous in Colorado Plateau. Am. ·. ,ff ,C Assoc. Pet. Geol. Bull., 36 (9):1774-1796.

Thayn, G. F. Three new species of petrified wood from the lower Cret- aceous Cedar Mountain Formation of Utah. (Masters thesis, Brigham Young University, Utah, 1973).

Thomas, H. H. and N. Bancroft 1913. Cuticles of cycads and Bennetti- tales. Trans. Linn. Soc. London (Bot.), 8:155-204.

Wagner, W. H. 1964. The evolutionary patterns of living ferns. In origin and evolution of fems (ed. by T. Delevoryas). Mem. Torrey Bot. Club, 21 (5):86-95.

Ward, L. F. 1898. Descriptions of the species of Cycadeoidea, or the fossil trunks thus far determined from the Lower Cretaceous Rim of the Black Hills. U.S. Nat. Mus., Pr. 21:195-229 •

• L. F. 1899. The Cretaceous formation of the Black Hills as ---- i~dicated by fossil plants. U.S.G.S. Ann. Rpt. 19 (2):521-946.

Wieland, G. R. 1904. The proembryo of the Bennettiteae. Am. J. Sci. (4) 18:445-447 •

• G. R. 1906. American fossil cycads. Carnegie Inst. ·Wash., ---- Publ. 34 :1-196. 43

• G. R. 1916. American fossil cycads; 2, Taxonomy. Carnegie ---- Inst. Wash. Publ. 34:1-277.

Yowig, R. G. 1960. Dakota group of Colorado Plateau. Amer. Assoc. Pet. Geol. Bull., 44 (1):156-194. PLATES

44 45

EXPLANATIONOF PLATE I

Fig. 8. Overview of bluff from which the cycadeoids were collected. Trunks were recovered from both sides of the ridge, upper left.

Fig. 9. Lithology of collection site; CM,'Cedar Mountain For- mation; M, Morrison Formation.

Fig. 10. Petrified cycadeoid (c) and associated conifer em~ bedded in sandstone.

:.,, 46

PLATE I 47

EXPLANATIONOF PLATEII

Fig. 11. Cycadeoidea medullara sp. nov. Complete trunk. X 0.14. Holotype. B.Y.U. 2270.

Fig. 12. Cycadeoidea medullara sp. nov. Surface features of armor; note transverse fracture through peduncle (p) and bracts (b). X 0.6. Holotype. B.Y.U. 2270.

•Fig. 13. Cycadeoidea medullara sp. nov. Tangential section through trunk armor; note distorted leaf bases (lb) separated by ramentious walls (rw) and peduncle (p). X 0.6. Holotype. B.Y.U. 2270. Fig. 14. Cycadeoidea medullara sp. nov. Longitudinal view of trunk apex; note position of meristematic region (m), scale leaves (s), and a young cone (c). X 0.5. Holotype. B.J.U.· 2270.

Fig. 15. Cycadeoidea medullara sp. nov. Transverse section of trunk midregion illustrating relationship of pith, vascular tissue, ·cortex, and armor. Detail: cs, cone socket. X 0.3 Holotype. B.Y.U. 2270. 48

PLATE II 49

EXPIANATIONOF PLATEIII

Fig. 16. Cycadeoidea medullara sp. nov. Incomplete trunk. X 0.17. Paratype. B.Y.U. 2271.

Fig. 17. Cycadeoidea medullara sp. nov. Young ovulate cone with short peduncle encased in ramentlllll-. Nature of debris at tip of receptacle is indeterminable. X 1.5. Holotype. B.Y.U. 2270.

Fig. 18. Cycadeoidea medullara sp. nov. Transverse section of trunk; note complete ovulate cone (c). X 0.3. Paratypa. B.Y.U. 2271. Fig. 19. Cycadeoidea medullara sp. nov. Tangential section of armor near cortex illustrating leaf bases. X 0.8. Holotype. B.Y.U. 2270.

Fig. 20. Cycadeoidea medullara sp. nov. Tangential section of armor, taken 2 cm exterior to that shown in Fig. 19 0 , illustrating leaf ·base distortion caused by cone expansion. X 0.8. Holotype. B.Y.U. 2270. 50

PLATE Ill 51

EXPIANATIONOF PLATEIV

Fig. 21. Cycadeoidea medullara sp. nov. Transverse section of trunk; note pith (pi), medullary sheath (ms), xylem (x), phloem (p), and spirally arranged traces departing from the vascular cylinder and segmenting in the cortex. X 1. Paratype. B.Y.U. 2271.

Fig. 22. Cycadeoidea medullara sp. nov. Longitudinal section of older ovulate cone; note absicission layers (ab) and shoulder of tissue (s) at the base of the eroded receptacle. X 1. Holotype. B.Y.U. 2270. Fig. 23. Cycadeoidea medullara sp. nov. Transverse section of trunk, longitudinal section of older ovulate cone. X 1.3. Para- type. ·B.Y.U. 2271.

Fig. 24. Cycadeoidea medullara sp. nov. Longitudinal section of bisporangiate cone; note retouched insect tunnel (t). X 1.5. Holo- type. B.Y.U. 2270.

Fig. 25. Cycadeoidea medullara sp. nov. Transverse section of trunk, longitudinal section of older ovulate cone illustrating abscissional layers and eroded receptacle ·(r). X 1.3. Paratype. B. Y.U. 2271.

Fig. 26. Cycadeoidea medullara sp. nov. Transverse section of trunk, longitudinal section of cone; note that the receptacle has been abscissed leaving the cone socket (cs). X 1.3. Paratype. B.Y.U. 2271. Fig. 27. Cycadeoidea medullara sp. nov. Transverse section of trunk illustrating position of bisporangiate cone and synangia (s). Young collateral bundles are visable in the stele. X 0.7. Holotype. B.Y.U. 2270. 52

PLATE IV 53

EXPLANATIONOF PLATEV

Fig. 28. Cycadeoidea medullara sp. nov. Thin section illustrating mature pollen grain. X 340. Holotype. B.Y.U. 2270.

Fig. 29. Cycadeoidea medullara sp. nov. · Pollen retrieved by pollen analysis from the bisporangiate. cone. X 285. Holotype. B.Y.U. 2270.

Fig. 30. Cycadeoidea medullara sp. nov. Synangium from bisporangiate cone illustrating longitudinal chambers. X 25. Holotype. B.Y.U. 2270.

Fig. 31. Cycadeoidea medullara sp. nov. Enlarged view of Fig. 30., illustrating longitudinal chambers containing pollen. X 82. Holotype. B.Y.U. 2270.

Fig. 32. Cycadeoidea medullara sp. nov. Transverse view of chambered synangia; note wall (w) separating chambers. X 25. Holo- type. B.Y.U. 2270.

Fig. 33. Cycadeoidea medullara sp. nov. Transverse section through ovules (o) and ovuliferous scales (os). X 100. Holotype. B. Y.U. 2270.

Fig. 34. Cycadeoidea medullara sp. nov. Longitudinal view of the base of the bisporangiate cone receptacle illustrating longitudinal view of ovules and ovuliferous scales. X 36. Holotype. B.Y.U. 2270. 54

PLATEV 55

EXPLANATIONOF PLATEVI

Fig. 35. Cycadeoidea medullara sp. nov. Longitudinal section near the tip of a bract (b) illustrating departure of ramental scales. X 12. Holotype. B.Y.U. 2270.

Fig. 36. Cycadeoidea medullara sp_ nov. Cuticle pattern retrieved from pollen analysis. X 220. Holotype. B.Y.U. 2270.

Fig. 37. Cycadeoidea medullara sp. nov. Epidermis of leaf base with syndetocheilic stomata. X 134. Holotype. B.Y.U. 2270.

Fig. 38. Cycadeoidea medullara sp. nov. Transverse section of ramental scales. X 291. Holotype. B.Y.U. 2270.

Fig. 39. Cycadeoidea medullara sp. nov. Epidermis of leaf base with syndetocheilic stomata. X 27. Holotype. B.Y.U. 2270.

F~g. 40. Cycadeoidea medullara sp. nov. Epidermis illustrating alligned position of cells. X 194. Holotype. B.Y.U. 2270 •

..; 56

PLATE VI 57

EXPLANATIONOF PLATEVII

Fig. 41. Cycadeoidea medullara sp. nov. Longitudinal section illustrating xylem (left), oblique medullary sheath (center), and loosely arranged interior pith (right). X 25. Holotype. B.Y.U. 2270.

Fig. 42. Cycadeoidea medullara sp. nov. Tangential section illustrating scalariform tracheids, near primary xylem separated by large lenticular medullary rays (r). X 180. Holotype. B.Y.U. 2270.

Fig. 43. Cycadeoidea medullara sp. nov. Transverse section illustrating xylem (left), medullary sheath (center), and loosely arranged interior pith (right). X 25. Holotype. B.Y.U. 2270. Fig. 44. Cycadeoidea medullara sp. nov. Loosely arranged interior pith and mucilage sacs. X 25. Holotype. B.Y.U. 2270.

Fig. 45. Cycadeoidea medullara sp. nov. Globular structures lining mucilage sacs. X 188. Holotype. B.Y.U. 2270.

Fig. 46. Cycadeoidea medullara sp. nov. Transverse section of ovules and ovuliferous scales, illustrating arrangement. X 41. Holotype. B.Y.U. 2270. 58

PLATE VII 59

EXPLANATIONOF PLATEVIII

Fig. 47. Cycadeoidea medullara sp. nov. Transverse section of primary xylem wedges separated by the large lenticular rays (r). X 167. Holotype. B.Y.U. 2270.

Fig. 48. Cycadeoidea medullara sp. nov. Tangential section of secondary wood illustrating uniseriate to triseriate medullary rays that separate the scalariformly pitted tracheids. X 167. Holotype. B.Y.U. 2270. Fig. 49. Cycadeoidea medullara sp. nov. Tracheids exhibiting large elliptical aperatures. X 180. Holotype. B. Y .U. 2270.

Fig. 50. Cycadeoidea medullara sp. nov. Transverse section of cambial zone illustrating radially alligned vascular tissue. X 20. Bolotype. B.Y.U. 2270.

Fig. 51. Cycadeoidea medullara sp. nov. Transverse section of cambial zone. X 100. Holotype. B.Y.U. 2270.

Fig. 52. Cycadeoidea medullara sp. nov. Transverse section of pericyclic strands at periphery of phloem. C 100. Holotype. B.Y.U. 2270. 60

PLATE VIII 61

EXPLANATIONOF PLATEIX

Fig. 53. Cycadeoidea cleavelandii sp. nov. Incomplete trunk. X 0.4. Holotype. B. Y. U. 22 72 • Fig. 54. Cycadeoidea cleavelandii sp. nov. Transverse section of trunk illustrating relationship of pith, vascular tissue, cortex, and armor. X 0.5. Holotype. B.Y.U. 2272.

Fig. 55. Cycadeoidea cleavelandii sp. nov. Transverse section of trunk; note xylem (x), phloem (p), and emerging trace (t). Seg- mented traces are visable in the cortex. X 2.5. Holotype. B.Y.U. 2272.

Fig. 56. Cycadeoidea cleavelandii sp. nov. Transverse section of parenchyma cells in the pith. X 161. Holotype. B.Y.U. 2272.

Fig. 57. Cycadeoidea cleavelandii sp. nov. Transverse section of trunk illustrating narrow cortex and wide, undisturbed leaf bases. X 1.3. Holotype. B.Y.U. 2272. 62

PLATE IX 63

EXPLANATIONOF PLATEX

Fig. 58. Cycadeoidea cleavelandii sp. nov. Transverse section of ramental scales. X 140. Holotype. B.Y.U. 2272.

Fig. 59. Cycadeoidea cleavelandii sp. nov. Tangential section of secondary xylem illustrating uniseriate to biseriate medullary rays. X 160. Holotype. B.Y.U. 2272.

Fig. 60. Cycadeoidea cleavelandii sp. nov. Tracheids in transverse section. X 160. Holotype. B.Y.U. 2272.

Fig. 61. Cycadeoidea cleavelandii sp. nov. Scalariform thickenings on tracheid walls. X 160. Holotype. B.Y.U. 2272.

Fig. 62. Cycadeoidea cleavelandii sp. nov. Transverse section of cambial zone illustrating phloem fibers (left), and tracheids (right). X 160. Holotype. B.Y.U. 2272.

Fig. 63. Cycadeoidea cleavelandii sp. nov. Transverse section of primary xylem wedges separated by medullary rays. X 160. Holotype. B.Y.U. 2272. 64

PLATE X 'lWONEW SPECIES OF THEGENUS CYCADEOIDEA FROMTHE LOWER CRETACEOUS OF UTAH

H. Blaine Furniss

Department of Botany and Ra.nge Science

M.S. Degree, August, 1975

ABSTRACT.

~c1,deoidea medullara and~. cleavelandii, two new species of the genus Cvcadeoidea, have been recovered from the Lower Cretaceous . Cedar Mountain Formation of Utah. They have been described in histolo- gic detail and relationships with ·similar species are set forth. Mono- ecism and pollination mechanisms have been discussed in connection with · £.:_ medullara. This data contributes to our knowledge of the diverse composition of Lower Cretaceous floras in Utah. COMMITTEEAPPROVAL: