Description of new materials of lanthasaurus hardestiorum (Eupelycosauria: Edaphosauridae) and a re-evaluation of its phylogenetic relationships

by

David M. Mazierski

A thesis submitted in conformity with the requirements for the degree of Master of Science Ecology and Evolutionary Biology University of Toronto

© Copyright by David M. Mazierski 2008 Library and Bibliotheque et 1*1 Archives Canada Archives Canada Published Heritage Direction du Branch Patrimoine de I'edition

395 Wellington Street 395, rue Wellington Ottawa ON K1A0N4 Ottawa ON K1A0N4 Canada Canada

Your file Votre reference ISBN: 978-0-494-45022-2 Our file Notre reference ISBN: 978-0-494-45022-2

NOTICE: AVIS: The author has granted a non­ L'auteur a accorde une licence non exclusive exclusive license allowing Library permettant a la Bibliotheque et Archives and Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par Plntemet, prefer, telecommunication or on the Internet, distribuer et vendre des theses partout dans loan, distribute and sell theses le monde, a des fins commerciales ou autres, worldwide, for commercial or non­ sur support microforme, papier, electronique commercial purposes, in microform, et/ou autres formats. paper, electronic and/or any other formats.

The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in et des droits moraux qui protege cette these. this thesis. Neither the thesis Ni la these ni des extraits substantiels de nor substantial extracts from it celle-ci ne doivent etre imprimes ou autrement may be printed or otherwise reproduits sans son autorisation. reproduced without the author's permission.

In compliance with the Canadian Conformement a la loi canadienne Privacy Act some supporting sur la protection de la vie privee, forms may have been removed quelques formulaires secondaires from this thesis. ont ete enleves de cette these.

While these forms may be included Bien que ces formulaires in the document page count, aient inclus dans la pagination, their removal does not represent il n'y aura aucun contenu manquant. any loss of content from the thesis. Canada Description of new materials of Ianthasaurus hardestiorum (Eupelycosauria: Edaphosauridae) and a re-evaluation of its phylogenetic relationships

M.Sc. EEB 2008 David M. Mazierski Ecology and Evolutionary Biology University of Toronto

ABSTRACT

Ianthasaurus hardestiorum, a basal edaphosaurid from the Upper Pennsylvanian of Garnett,

Kansas, has been described on the basis of two incomplete, juvenile specimens and a series of disarticulated vertebral elements. New material of this poorly known species includes previously unknown bones and increases knowledge of the anatomy and variation in this taxon. The complete ossification of the neural arches and the overall larger size of the vertebrae relative to those previously described suggests that they were part of an adult individual.

Tooth morphology in the marginal dentition more closely resembles that seen in the genus

Edaphosaurus. Phylogenetic analysis of edaphosaurid synapsids supports the hypothesis that

Ianthasaurus is the sister taxon of all other members of the clade. However, the incomplete fossil record of other referred edaphosaurids such as Lupeosaurus and Glaucosaurus makes full resolution of their phylogenetic interrelationships difficult to assess.

//' ACKNOWLEDGEMENTS

I would like to begin by thanking my supervisor Dr. Robert R. Reisz for his moral, academic, personal and financial support in granting me the opportunity to embark on a Masters degree at this late but pivotal point in my career as a medical and scientific illustrator and faculty member in Biomedical Communications at the University of Toronto. It has been a privilege to work with him, and in his lab. In return, I promise never again to mix up "Ghzelian" and

"gazillion" as measures of time and stratigraphic age. Special thanks also go to Diane Scott, whose extraordinary paleontological illustrations got me interested in working in the Reisz

Lab in the first place, for her guidance and patience with preparation (especially the intricacies of tiny palatal teeth). Diane took most of the photographs, which also served as the starting point for my illustrations. I am also grateful to have shared in the company, knowledge and

sustenance of the UTM Reisz Lab biome: Nic Campione, Jorg Frobisch (and McGill's honorary

Reisz Lab member Nadia Frobisch), Kaila Folinsbee, (Dr.) David Evans, Hillary Maddin and

Linda Tsuji. I could not have wished for a more welcoming, supportive and engaging group of

colleagues. In particular, I will forever be indebted to Nic, who helped me out so often that I

daresay that I could not have gotten through this without him. If I have retained any knowledge

of phylogenetics at all, it is through his efforts.

Dr. Sean Modesto, of Cape Breton University (another Reisz Lab alumnus), was also an

inspiration and primary source of information on the Edaphosauridae. His phylogenetic data

matrices for Glaucosaurus megalops and Edaphosaurus boanerges formed the basis for my

evaluation, and he provided advice and answered questions throughout my research period.

Kevin Seymour of the Royal Ontario Museum and David Berman of the Carnegie Institute,

Pittsburgh assisted me with access to their collections for study. I would also like to extend

thanks to my committee member Dr. Sasa Stefanovic, who proposed many useful ideas for my

/// phylogenetic analysis, Dr. Jason Head, for suggestions regarding potential research related to extant herbivorous reptiles, and California State University grad student Adam K. Huttenlocker, for sharing his biostratigraphic data with me.

Outside of the world of vertebrate paleontology, I would like to thank my colleagues in

Biomedical Communications, especially Linda Wilson-Pauwels and Shelley Wall. In her role as BMC Program Director, Linda encouraged and supported my pursuit of this degree. Fellow

BMC faculty member and dear friend Shelley provided incalculable amounts of moral support and helped me keep my head on straight as we managed our undergraduate and graduate teaching responsibilities throughout the past two years.

Finally, I save my deepest and most heartfelt thanks for the Home Team: my wife Julia Rogers

and my children Evan and Rachel. Without their love and support, this paper could never have been written, let alone started, and I hope that the rewards from this endeavor will make up for the gifts they have given me.

iv TABLE OF CONTENTS

Abstract ii Acknowledgements iii List of Figures vi Introduction 1 Abbreviations 6 Systematic Paleontology 6 Description 8 Phylogenetic Analysis 30 Discussion 38 References 42 Appendix 1: Character Description 46 Appendix 2: Data Matrix 52 Appendix 3: Supplemental Figures 53 Appendix 4: PAUP* Data 60

v LIST OF FIGURES

Figure 1: Cladogram illustrating hypothesis of phylogenetic relationships of basal synapsids p.l

Figure 2: Valid taxa assignable to the Edaphosauridae p.2

Figure 3: Stratigraphy of Rock Lake Shale Member, Upper Pennsylvanian of Kansas p. 3

Figure 4: Approximate location of Garnett, Kansas during the late Pennsylvanian, ~315 M.A p. 4

Figure 5: Location of Garnett, Kansas p. 7

Figure 6: Schematic illustration of ROM 59933 (block) p.8

Figure 7: Ianthasaurus hardestiorum, left maxilla photo, lateral view (ROM 59933) p.10

Figure 8: Ianthasaurus hardestiorum, left maxilla, lateral view (ROM 59933) p.l 1

Figure 9: Ianthasaurus hardestiorum, left maxilla (detail), lateral view (ROM 59933) p. 11

Figure 10: Ianthasaurus hardestiorum, right quadrate and dorsal rib photo (ROM 59933) p. 12

Figure 11: Ianthasaurus hardestiorum, right quadrate and dorsal rib (ROM 59933) p.12

Figure 12: Ianthasaurus hardestiorum, left postorbital, presacral vertebral spines (ROM 59933) p.14

Figure 13: Ianthasaurus hardestiorum, right pterygoid (ROM 59933) p.15

Figure 14: Ianthasaurus hardestiorum, right pterygoid and dorsal rib photo (ROM 59933) p.15

Figure 15: Ianthasaurus hardestiorum, right pterygoid and palatal teeth photo (ROM 59933) p.16

Figure 16: Ianthasaurus hardestiorum, left mandible, medial surface photo (ROM 59933) p. 18

Figure 17: Ianthasaurus hardestiorum, left mandible, medial surface (ROM 59933) p. 19

Figure 18: Ianthasaurus hardestiorum, left mandible, medial surface detail (ROM 59933) p.19

Figure 19: Ianthasaurus hardestiorum, paired articulated vertebral bodies (ROM 59933) p.21

Figure 20: Ianthasaurus hardestiorum, paired articulated mid-thoracic vertebrae (ROM 59933) p.21

Figure 21: Ianthasaurus hardestiorum, mid-thoracic vertebra, ribs and phalanges photo (ROM 59933) ..p.22

Figure 22: Ianthasaurus hardestiorum, mid-thoracic vertebra, ribs and phalanges (ROM 59933) p.23

Figure 23: Ianthasaurus hardestiorum, presacral & caudal vertebrae, hemal arches photo (ROM 59933) p.25

Figure 24: Ianthasaurus hardestiorum, presacral & caudal vertebrae, hemal arches (ROM 59933) p.26

Figure 25: Ianthasaurus hardestiorum, dorsal ribs, cervical rib, phalangeal elements (ROM 59933) p. 29

Figure 26. Phylogenetic analysis: Ianthasaurus & Edaphosauridae p.32

Figure 27: Phylogenetic analysis: Ianthasaurus & Edaphosauridae minus dental characters p.33

Figure 28: Phylogenetic analysis: Ianthasaurus & Lupeosaurus kayi p.34

vi Figure 29: Phylogenetic analysis: Ianthasaurus & Edaphosaurus colohistion p.35

Figure 30: Phylogenetic analysis: Ianthasaurus & Edaphosauridae, all taxa p.36

Figure 31: Ianthasaurus hardestiorum, left lateral maxilla measurements (ROM 59933) p.53

Figure 32: Ianthasaurus hardestiorum, left medial mandibular measurements (ROM 59933) p.53

Figure 33: Ianthasaurus hardestiorum, right quadrate and dorsal rib measurements (ROM 59933) p.54

Figure 34: Ianthasaurus hardestiorum, right pterygoid and dorsal rib measurements (ROM 59933) p.54

Figure 35: Ianthasaurus hardestiorum, left postorbital and neural spine measurements (ROM 59933) ....p.55

Figure 36: Ianthasaurus hardestiorum, vertebra and neural spine measurements (ROM 59933) p.55

Figure 37: Ianthasaurus hardestiorum, caudal and presacral vertebra measurements (ROM 59933) p.56

Figure 38: Ianthasaurus hardestiorum, presacral vertebra measurements (ROM 59933) p.56

Figure 39: Ianthasaurus hardestiorum, dorsal vertebra and rib measurements (ROM 59933) p.57

Figure 40: Ianthasaurus hardestiorum, dorsal ribs, cervical rib, phalangeal measurements (ROM 59933)p.58

Figure 41: Reconstruction of broken vertebral bodies and spines p.59

VII INTRODUCTION

Edaphosauridae is a monophyletic group of herbivorous synapsids that range temporally from the Upper Pennsylvanian to the Lower Permian. First described by Cope in 1882, edaphosaurids have been found in deposits in the American Southwest as well as from West

Virginia, Pennsylvania, Ohio and central Europe (Romer and Price, 1940; Reisz, 1986). They are known primarily from the red beds of Texas; four of the best-known and most thoroughly described species (including the genotype Edaphosaurus cruciger, as well as E. boanerges and E. pogonias) have been found there (Romer and Price, 1940; Reisz, 1986). The group is diagnosed primarily by their hyper-elongate presacral neural spines (Modesto and Reisz, 1990a; Modesto,

1995). The spines are round in cross-section, and in the larger species the spines lean noticeably towards the head (in the case of the most cranial vertebrae) or towards the tail (for the most caudal presacral vertebrae). The spines also bear tubercles on their lateral surfaces; the basal lateral tubercles are always paired (Modesto and Reisz, 1990). Additional synapomorphies for the Edaphosaurus clade are the presence of tooth plates on the palate and inner surface of the mandible, and the loss of contact between the postorbital and supratemporal (Reisz, 1986;

Modesto, 1995).

Reptilia

Amniota— Caseasauria

Synapsida Varanopidae

LEupelycosauria-^ Ophiacodontidae

Edaphosauridae

• Haptodontidae

• Sphenacodontidae

• Therapsida

Figure 1: Simplified cladogram illustrating hypothesis of phylogenetic relationships of basal synapsids (modified from Reisz, 1986; Reisz et al, 1982; Laurin, 1993; Berman et al, 1995; Modesto, 1995)

1 E.D. Cope is responsible for the first formal description of Edaphosaurus; he published four papers between 1877 and 1886 describing additional materials assigned to the clade (Cope,

1877; Cope, 1882; Cope, 1884; Cope, 1886). Further taxa were described by Case (1908),

Williston and Case (1913), Williston (1915), Romer (1937), Romer and Price (1940) and

Berman (1979). The earliest occurring member of the clade was Naosaurus raymondi (Case,

1908; Modesto and Reisz, 1990b), later synonymized with Edaphosaurus (Romer and Price,

1940), from the Round Knob Formation, Conemaugh Group, Upper Pennsylvanian of Pitcairn,

Pennsylvania. However, the collection of fossils assigned to Edaphosauridae from the Rock Lake

Member of the Stanton Formation exposures near Garnett, Kansas has extended the earliest boundary for the existence of these basal synapsids further into the Carboniferous (Zeller, 1968;

Reisz et al, 1982; Sawin et al, 2006)(Fig. 3). The Rock Lake Member is composed of transgressive marine, calcareous mudstones (Reisz et al, 1982) which were assigned to the Kasimovian/

Ghzelian transition, approximately 304 M.A. (million years ago) (Reisz et al, 1982; Zeller, 1968).

Recent identification of conodonts in higher Kansas strata and their correlation with similar

Family Edaphosauridae Cope 1882 Genus Edaphosaurus Cope 1882 E. cruciger Cope 1882 = Dimetrodon cruciger Cape 1878 = Edaphosaurus microdus Cope 1887 E. pogonias Cope 1882 = Naosaurus claviger Cope 1886 = Brachycnemius dolichomerus Williston 1911 E. novomexicanus Williston and Case 1913 E. boanerges Romer and Price 1940 E. colohistion Berman 1979 Genus Glaucosaurus Williston 1915 G. megalops Williston 1915 Genus Lupeosaurus Romer 1937 I. kayi Romer 1937 Genus Ianthasaurus Reisz and Berman 1986 I. hardestiorum Reisz and Berman 1986

Figure 2: Taxa assignable to the Edaphosauridae (modified from Reisz, 1986)

2 Chase Group Lower Gearyan Stage Permian

Permian-Carboniferous Group Boundary ~299 M.A.

Admire Group Wabaunsee Group Shawnee Group Virgilian Stage Lawrence Formation Douglas Stranger Formation Group

South Bend Limestone Member Upper Bosk Lake ShataMember , Pennsylvanian s stonerUtrwwtoiiei Member - , Stanfttn Limestone Series Eudora Shale Member Lansing Captain Creek Shate Member Group VJlas'Stjaie

Plattsburg Limestone

Bonner Springs Shafe e Missourian Wyandotte Kansas City Stage Limestone I Group Lane Shale s

Pieasonton Group Marmaton Desmoinian Middle Group Stage Pennsylvanian Series

Figure 3: Stratigraphy of Rock Lake Shale Member, Upper Pennsylvanian of Kansas (modified from Zeller, 1968; Reisz et al, 1982; Sawin et al, 2006) fauna in the southern Ural Mountains has placed the Carboniferous-Permian boundary at the Bennett Shale Member of the Red Eagle Limestone, which effectively pushes the Stanton

Formation further back into the Kasimovian (Sawin et al, 2006).

The Rock Lake Shales of the Garnett site have proven to be a productive source of

Pennsylvanian floral and faunal remains since the 1930s (Reisz et al, 1982), including many basal Permo-Carboniferous synapsids. Vertebrates collected from this locality include the haptodontid Haptodus garnettensis (Currie, 1977), the small diapsid Petrolacosaurus kansensis

(Lane, 1945; Peabody, 1952; Reisz, 1977; Reisz, 1981), and an as-yet undescribed ophiacodontid

(Reisz and Berman, 1986), making this one of the most diverse assemblages of Pennsylvanian terrestrial fauna known (Reisz et al, 1982; Kissel and Reisz, 2004). It is from this locality that all of the fossils assigned to lanthasaurus have been found (Reisz and Berman, 1986; Modesto and

Reisz, 1990).

The holotype of lanthasaurus, KUVP 69035, was described by Reisz and Berman in 1986. Along with disarticulated elements from adjacent blocks (ROM 29940 and 29942), it was believed to represent an immature specimen, based on the incomplete ossification of the neural arches which resulted in disassociation and loss of the vertebral centra. Reisz and Berman (1986) also attributed three presumed adult vertebrae (ROM 29941) to lanthasaurus; they are fully ossified, as well as 15% larger than the homologous vertebra of the holotype. The presence of pointed, slightly recurved marginal teeth in lanthasaurus suggested that it represented a basal edaphosaurid that may have been faunivorous and an evolutionary precursor of the more derived, large herbivorous Edaphosaurus (Reisz and Berman, 1986).

A second specimen of an immature individual comprised of a nearly complete skull roof, left angular, 23 presacral and eight caudal vertebral neural arches and spines, pubis, ilium and

Figure 4: Approximate location of Garnett, Kansas during the late Pennsylvanian, -315 M.A. (modified from Blakey, 2005)

4 ischium was described by Modesto and Reisz in 1990. The nearly complete preservation of the skull roof allowed Modesto and Reisz to describe the long, gracile skull of Ianthasaurus in more detail and describe the morphological similarities between the quadratojugal, frontal, parietal and postfrontal of Ianthasaurus and Haptodus. This new material supported the hypothesis of an edaphosaur-sphenacodont clade, whereas the presacral neural spine morphology of

Ianthasaurus clearly indicated its relationship to the more derived Edaphosaurus. Unfortunately, no tooth-bearing elements were present to provide further evidence for the hypothesis that

Ianthasaurus had an insectivorous diet. Modesto and Reisz (1990) proposed that the post- cranial morphological indicators listed below could be used to identify insectivorous and herbivorous edaphosaurids:

Characteristic Insectivorous edaphosaurids Herbivorous edaphosaurids Body size small large Trunk elongate short Rib shape curved proximally strongly curved throughout Rib tubercles well-developed tubercula lacking proper tubercles Cervical/dorsal vertebral centra length cervicals longer than dorsals cervicals shorter than dorsals

ROM 59933, the subject of this paper, is the third formal description of this morphologically

primitive member of the Edaphosauridae. It demonstrates well ossified vertebrae, fully joined

neural arches and centra, and taller, more robust vertebral spines, along with intact, in situ

intercentra. In addition, this specimen possesses well-preserved skeletal material unknown

from other described or referred Ianthasaurus specimens. In particular, the maxilla, pterygoid,

and section of mandible shed new light on the dental morphology of Ianthasaurus, as teeth

present in the earlier described specimens were poorly preserved. This will allow us to update

and revise previously generated phylogenies of the Edaphosauridae based on morphological

traits, and hopefully gain a better understanding of the transition to herbivory that was an

important adaptation of this clade.

5 ABBREVIATIONS

CM, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, USA; KUVP, University of Kansas Museum of Natural History, Lawrence, Kansas, USA; ROM, Royal Ontario Museum,

Toronto, Ontario, Canada.

SYSTEMATIC PALEONTOLOGY

Subclass: SYNAPSIDA Osborn, 1903

Suborder: EUPELYCOSAURIA Kemp, 1982

Family: EDAPHOSAURIDAE Cope, 1882

Genus: IANTHASAURUS Reisz and Berman, 1986

Type species: Ianthasaurus hardestiorum Reisz and Berman, 1986

Holotype: KUVP 69035, nearly complete series of 27 articulated presacral neural arches and vertebral spines, one cervical, three anterior and fragments of four posterior dorsal ribs,

disarticulated skull roof elements from the right side consisting of the lacrimal, prefrontal,

postfrontal, postorbital and squamosal, posterior two thirds of the right mandible, and a left

humerus.

Referred specimens: ROM 22940, partial dorsal neural arch with a complete neural spine, a

first sacral rib and seven caudal ribs; ROM 29941, a cervical vertebra, a dorsal vertebra with

associated right rib and a lumbar vertebra with an attached rib; ROM 29942, disarticulated and

fragmentary elements of the skull and postcranial skeleton consisting of the maxillae, left jugal,

postfrontals, postorbital, anterior coronoid, neural arches and spines, three dorsal and a caudal

centrum, an intercentrum, presacral ribs, a caudal rib, right scapula and anterior coracoid,

6 nearly complete left pelvis, femur and manus (Reisz and Berman, 1986); ROM 37751, semi- articulated skull roof, 23 presacral vertebrae, disarticulated pelvic girdle and hind limb elements

(Modesto and Reisz 1990).

CM 34449, partial right maxilla; CM 34500 and CM 34576, partial neural spines; CM 34577, dorsal vertebra and base of neural spine; CM 34578, dorsal portion of right scapular blade;

CM 34579, left femur; CM 34580, left astragalus; CM 34581, partial right femur; CM 47700, numerous isolated centra and spines, all attributed to Ianthasaurus sp. (Sumida and Berman,

1993).

ROM 59933 consists of the left maxilla, right quadrate, left postorbital, right pterygoid, anterior portion of the left mandible, seven whole or partial presacral vertebrae, four whole or partial

caudal vertebrae with two hemal arches, eight ribs and seven phalanges.

HORIZON AND TYPE LOCALITY

Rock Lake Member, Stanton Formation, Lansing Group, Missourian Series, Upper

Pennsylvanian (Kasimovian); NW 1/4, NE 1/4, sec. 5, tp. 20s, rge. 19E, Putnam Township,

Anderson County, Kansas (Figs. 3 & 5).

Figure 5: Location of Garnett, Kansas.

7 Revised Diagnosis (modified from Modesto and Reisz 1990, current revisions in bold type):

A small edaphosaur characterized by the following two autapomorphies: an elongate, cross- barred dorsal process on the axis and at least 29 presacral vertebrae. Ianthasaurus differs from other edaphosaurs in the following features: skull long, equal to eight dorsal centra; frontal broad and long anteriorly, with lateral lappet located just posterior to midpoint; parietal with greatest breadth at level of pineal foramen; maxilla elongate with 30-40 peg-like teeth with conical, fluted cusp tips; caniniform teeth present; no development of enlarged tooth plates on the lower jaw; postaxial cervical vertebrae slightly longer than succeeding presacral vertebrae; neural arches of presacral vertebrae laterally excavated and bearing short transverse processes; maximum of eight lateral tubercles on each side of neural spine, with some proximal tubercles supported ventrally by slight webbing; no tubercles on neural spines of the posterior region of presacral column; trunk ribs strongly curved proximally and bearing well-developed tubercula; ilium with well-developed, blade-like posterior process.

Figure 6: Schematic illustration of ROM 59933, showing locations of various skeletal elements on the bedding plane; (*) indicates a small section of the slab that broke off and was prepared from the opposite side.

13/14/15 Numbers refer to figure numbers found on subsequent pages; scale bar = 1 cm. DESCRIPTION

Six of the seven presacral vertebrae are preserved as articulated pairs with intercentra present, as are three of the four caudal vertebrae. None of the other cranial or postcranial elements are articulated or preserved in proximity to their anatomical neighbors. Another bone, possibly the jugal, is also present, but it is too damaged to assess. The location and dispersal of the elements in relation to each other in the bedding plane are suggestive of fluvial deposition in shallow water, in which the remains of the animal settled after travel downstream and were covered by sediment (Kissel and Reisz, 2004). All of the material was prepared from one side only, depending on which surface was facing the plane of preparation. One narrow panel from the edge of the block was broken off and inadvertently prepared from the opposite side; therefore, two articulated vertebrae whose spines crossed the break were prepared on the opposite side from that of the spines (they are reconstructed in Fig. 41). During collection, the bedding plane was cut into square sections for removal, resulting in parts of the specimen being left on an adjacent slab of rock whose current location is unknown.

SKULL AND LOWER JAW

The left maxilla (Figs. 7, 8,9 and 31) is complete, with only minor crushing damage. The

lateral surface was prepared. As in the holotype, it possesses a short concave emargination

forming the posteroventral border of the external nares. There is a well-defined shelf where

the lacrimal overlaps and articulates with the maxilla. The posterior border where the maxilla

articulates with the jugal is damaged and difficult to assess. The marginal tooth row contains 26

teeth; accounting for gaps between the teeth, the total number of tooth positions is estimated

to be 37. The first four teeth are similar in shape, and increase in size up to the fifth preserved

9 Figure 7: Ianthasaurus hardestiorum, left lateral maxilla, ROM 59933.

10 Posteroventral border of Lacrimal articular surface external nares

Figure 8: lanthasaurus hardestiorum, left lateral maxilla, ROM 59933; scale bar = 1 cm.

Figure 9: lanthasaurus hardestiorum, detail of left lateral maxillary dentition, ROM 59933; scale bar = 1 cm.

77 Figure 10: Ianthasaurus hardestiorum, right quadrate and dorsal rib, ROM 59933.

Articular condyle

Dorsal rib

Squamosal articular surface

Figure 11: Ianthasaurus hardestiorum, right quadrate and dorsal rib, ROM 59933; scale bar = 1 cm.

12 tooth, which is 80% larger than the preceding tooth and caniniform in appearance. The 12 teeth distal to the caniniform tooth are the same size as the teeth immediately in front of the canine; the remaining teeth then decrease in size until the final tooth in the row is only 50% of the size of the mid-maxillary teeth. This condition more closely resembles that found in basal sphenacodontids rather than the most derived edaphosaurids, which possess isodont marginal dentition (Romer and Price, 1940).

Unlike previously described dental material attributed to Ianthasaurus (Reisz and Berman,

1986), the marginal teeth present in ROM 59933 are well preserved. The teeth are subcircular in cross section, and have either conical or slightly bulbous tips. The cusp tips bear tiny striations that begin three quarters of the distance of the tooth length from the base, and converge on the tip. These similarities to the dental morpology of Edaphosaurus are in contrast with the presence of a caniniform tooth and variation in size along the marginal tooth row, which is a basal character for eupelycosaurs and not present in Edaphosaurus.

The teeth of ROM 59933 are markedly different from the teeth in previously described

specimens of Ianthasaurus. The teeth in the holotype KUVP 69035 and referred specimen

ROM 29942 are sharply pointed and slightly recurved. This may be due to the juvenile status

of the previously described specimens, which were less well preserved than the fully ossified

material of ROM 59933. Another possible explanation for the differences in tooth shape may be

the intermingling of faunal remains in the bedding plane. Reisz and Berman (1986) observed

that the Garnett quarry deposits commonly presented partial skeletons that were intermingled

on the same plane and several eupelycosaur taxa were difficult to identify for this reason. The

position of the mandible relative to the vertebral column in the holotype KUVP 69035 as well

as the lack of duplicated elements and similar degree of ossification supports the belief that

all of the elements present come from one individual (Reisz and Berman, 1986); however,

13 I I

1

Figure 12: Ianthasaurus hardestiorum, left postorbital and two broken presacral vertebral spines, ROM 59933; scale bar = 1 cm. m

Postfrontal process of postorbital

#

14 91 PI £1 Zl U 01 6

Figure 13: Ianthasaurus hardestiorum, right pterygoid, ROM 59933.

Marginal teeth Palatal teeth

Figure 14: Ianthasaurus hardestiorum, right pterygoid and rib, ROM 59933; scale bar = 1 cm.

15 ^ is. ^ A • *

Marginal tooth row* Palatal teeth

Figure 15: Ianthasaurus hardestiorum, right pterygoid tilted laterally to demonstrate the exposed tips of the teeth on the pterygoid ramus, ROM 59933.

16 the lack of similar evidence in ROM 29942 suggests that while the neural spines present are presumably lanthasaurus, the poorly preserved and separate maxillary elements may in fact be parts of a different specimen. A third possible explanation for the difference in marginal tooth morphology between KUVP 69035 and ROM 59933 is that it maybe evidence of ontogenetic change, where the pointed, insectivorous teeth of the younger animal were replaced by peg­ like teeth more suited to trimming and crushing plant material as the animal matured. This cannot be ascertained without further evidence in the form of additional juvenile and mature specimens.

The right quadrate (Figs. 10,11 and 32) is trapezoidal in shape with the anterodorsal corner of the dorsal lamina forming an acute angle where it fits into the corresponding notch in the quadrate ramus of the pterygoid. The posterior margin bears a wide, coarse articular surface for the squamous. The proportions more closely resemble that of Edaphosaurus rather than a sphenacodont. The articular condyle is robust and well preserved, with a saddle-shaped articular surface for the lower jaw that confirms its affinity to the more derived members of the

Edaphosauridae. A small scar marks the point of attachment of the stapedial cartilage.

The postorbital (Figs. 12 and 34) forms the posterior margin of the orbit and the anterodorsal margin of the temporal fenestra. The left postorbital was found adjacent to two vertebral spines.

The parietal portion of this tripartite bone is the largest, being more than twice the width of the other two processes. It resembles the postorbital of Haptodus or Mycterosaurus, rather than Edaphosaurus. In Edaphosaurus, the parietal process is reduced to the point that the bone appears triangular in lateral view. Most of the surface of the postfrontal process consists of the lightly textured articular surface that would fit under the postfrontal, making the postorbital appear as an arch-shaped element in between the orbit and temporal opening.

17 Figure 16: Ianthasaurus hardestiorum, left mandible, medial surface, ROM 59933.

18 Coronoid

Mandibular symphysis

Figure 17: Ianthasaurus hardestiorum, left mandible, medial surface, ROM 59933; scale bar = 1 cm.

Figure 18: Ianthasaurus hardestiorum, detail of left mandible, symphysis and teeth, medial surface, ROM 59933; scale bar = 1 cm.

19 The pterygoid (Figs. 13,14,15 and 34) is unknown in all previous described Ianthasaurus material. The medial surface of the right pterygoid was prepared. The palatal ramus is flattened and twisted onto the same plane as the quadrate ramus, with some crushing damage evident on the massive transverse flange. Unlike Edaphosaurus, there is no palatal tooth plate. However, there appears to be a dense grouping of teeth on the ramus anteromedial to the larger marginal teeth, although they were almost impossible to prepare due to their delicate nature and size, and the dense matrix between the teeth. The tips of the teeth were exposed by careful preparation in this region (Fig. 15). Along the posterior border of the medial ramus are a row of large, medially compressed teeth with blunt conical tips. It appears that there is a second row of similar teeth anterior to these, although poor preservation has rendered this area difficult to prepare and diagnose without causing damage. The quadrate ramus displays a bifid shape, with well-defined articular surfaces for overlap with the quadrate. A small portion of the ectopterygoid remains articulated with the part of the transverse flange that blends into the palatine ramus.

The anterior third of the left mandible (Figs. 15,16,17 and 31) is present; the rest was lost during removal from the collection site. The medial surface of the mandible shows portions of the dentary, splenial and coronoid bones somewhat splayed and disarticulated. The median articular surface of the left dentary demonstrates the rugose face of the mandibular symphyseal facet. A deep ventrally-directed groove that leads to the edge of the meckelian fossa bisects the articular surface. Distally, the articular surfaces for the coronoid and splenial are visible due to the outward spreading of the three bones. The remaining dentary retains seven teeth; they are uniform in shape, which is circular in cross-section at their bases, tapering to a tip compressed buccal-lingually, bearing striations that converge on the cusp tips (Fig. 18). They are morphologically similar to the maxillary teeth. The first tooth present is the smallest; after a short diastema, the following three larger teeth form a group with the middle tooth being

20 Figure 19: Ianthasaurus hardestiorum, paired articulated vertebral bodies, ROM 59933; scale bar = 1 cm.

Figure 20: Ianthasaurus hardestiorum, paired articulated mid-thoracic vertebrae, ROM 59933; scale bar = 1 cm.

21 Figure 21: Ianthasaurus hardestiorum, mid-thoracic vertebra, ribs and phalanges, ROM 59933.

22 Detail of fig. 22 showing slight groove on the caudal surface of the neural spine; scale bar = 1

Figure 22: Ianthasaurus hardestiorum, mid-thoracic vertebra, ribs and phalanges, ROM 59933; scale bar = 1 cm.

23 the tallest. The slightly enlarged third tooth of the series is reminiscent of the condition seen in

Haptodus garnettensis but the size difference between the largest tooth and those making up the rest of the series is not as dramatic as seen in Haptodus, or in the more derived sphenacodontid

synapsids like Sphenacodon and Dimetrodon. In contrast, the marginal dentition of

Edaphosaurus is essentially isodont (Reisz, 1986). The remaining teeth are slightly larger than the first and are equal in size to each other. Without the posterior section of the mandible, the tooth count cannot be approximated for the lower jaw, nor can we determine whether there is

evidence of a lower tooth plate present as found in the more derived members of the clade.

The anterior portion of the splenial (Figs. 16 and 17) is preserved. The anteroventral edge

displays the roughened articular surface of the mandibular joint. Distally, the bone becomes

more convex in profile with a thin, flattened dorsal lip that articulates with the dentary along its

length.

Only a small sliver of the anterior coronoid (Figs. 16 and 17) is present. It bears two teeth, with

positions for at least two more anterior to the saw cut. No coronoids were found in the holotype

KUVP 69035 (Reisz and Berman, 1986).

AXIAL SKELETON

Vertebrae of Permo-Carboniferous synapsids provide much of the diagnostic evidence for

distinguishing species within their respective clades, in particular due to the distinctive

morphology of the neural spines. The vertebral column of ROM 59933 is represented by

seven presacral and four caudal vertebrae, including two hemal arches. Interestingly, all of the

presacral vertebrae but one were preserved as articulated pairs, complete with intercentra.

24 00

Ifl •w

w

w

o> o, / •eu** S *v9tk ^mm Figure 23: Ianthasaurus hardestiorum, paired articulated presacral vertebrae, caudal vertebrae and hemal arches, ROM 59933.

25 Figure 24: Ianthasaurus hardestiorum, paired articulated presacral vertebrae, caudal vertebrae and hemal arches, ROM 59933; scale bar = 1 cm.

26 The morphology of the neural spines closely conforms to that described by Reisz and Berman

(1986) in most respects except in the number of lateral tubercles present. The proximal portions of the spines are laterally compressed, resulting in a greater cranial-caudal length (Reisz and Berman, 1986). This blends into a subcircular shape by the first tubercle and remains subcircular in profile all the way up to the blunted tip. In the holotype, the longest spines bear up to five pairs of tubercles (Reisz and Berman, 1986). In ROM 59933, one of the spines has six pairs of tubercles (Fig. 12 and 41), while the excellently preserved vertebra prepared on its caudal surface has eight pairs of tubercles, with the first two pairs demonstrating bilateral symmetry (Fig. 21,22 and 39). This difference in the number of tubercles maybe attributed to the more mature status of ROM 59933 compared with the holotype and ROM 37751, or the greater size of ROM 59933, or both. Also present on many of the proximal tubercles is webbing that blends the tubercle into the lateral edge of the spine, as seen in ROM 37751. In comparison to the single dorsal vertebra in ROM 29941, the dorsal vertebrae here possess much more robust spines. None of the spines demonstrate any anterior or posterior curvature, indicating that they occupied a mid-thoracic position. The vertebral spines of ROM 37751

(Modesto and Reisz, 1990) are also tall and straight, with the exception of the most caudal. The vertebral bodies and intercentra can only be compared to ROM 37751, as the holotype centra were disarticulated from the spines or lost altogether. The lateral surfaces of the neural arch display shallow pockets between the zygopophyseal ridges typical of many basal eupelycosaurs.

The zygopophyses conform to the recognized basal synapsid model, with anterior surfaces moderately tilted medially. The transverse processes possess well-defined cup-shaped articular facets for the costal capitulum. The intercentra between the two best-preserved vertebrae are crescent-shaped with a concave ventral surface, typical for edaphosaurids. One vertebra was preserved with its caudal surface facing the plane of preparation. With only minor crushing distortion, it clearly demonstrates the amphicoelus nature of basal synapsid vertebral centra.

27 groove along the posterior surface, as in referred specimen CM 34576 (Sumida and Berman,

1993). This groove may have held a blood vessel, as has been suggested for the deeper grooves found in the cranial and caudal faces of sphenacodontid neural spines, and reinforces the hypothesis that the edaphosaurid sail may have served a thermoregulatory function (Bennet,

1996).

The neural spine of one post-sacral vertebra is preserved. The spine is compressed mediolaterally, with a slight swelling at the tip. A deep excavation is present between the prezygopophyseal ridges. The spine is identical in proportion to a corresponding bone in ROM

37751 (Fig. 3, Modesto and Reisz, 1990); it is rectangular in a 2 to 3 ratio of width to height.

Adjacent to the neural spine are three more distal caudal vertebrae and two hemal arches. The

caudal vertebrae are flexed in a dorsally directed curve. Their spinous processes are greatly

reduced, suggesting that they are from a point in the last quarter of the tail, based on other basal synapsid skeletons. One hemal arch is obscured by the caudal vertebrae that lie on top

of it; the second preserved arch below the articulated caudals is complete, with a short ventral

process.

Eight ribs (Figs. 11,12,14, 21, 22, 25, 33, 34, 39 and 40) are present. One is a cervical rib, with

separate and well-defined capitular and tubercular articular areas. The shaft of the rib is flat and blade-like, nearly straight with a minimal distal curvature and a wide proximal portion that

tapers along its length. Five ribs from the dorsal series are present. All but one are similar in

length, and they all display a gentle 35° curve throughout their entire length. In contrast, the

ribs of Edaphosaurus are strongly curved throughout their length, resulting in a barrel-shaped

trunk (Romer and Price, 1940). The last two ribs are smaller in size and have a straight shaft

oriented almost 90° to the articular head; unfortunately, they are poorly preserved, with both

ends damaged or missing.

28 Seven separate phalanges are scattered across the bedding plane (Figs. 21,22,25, 39 and 40).

Three phalanges are articulated, but it is impossible to determine if they represent the manus or pes. Another is probably a metapodial, based on its proportions and stout proximal articular surface.

Cervical rib

Dorsal ribs

- Metapodial (?)

Figure 25: Ianthasaurus hardestiorum, dorsal ribs, cervical rib and phalangeal elements, ROM 59933; scale bar = 1 cm.

29 PHYLOGENETIC ANALYSIS

ROM 59933 possesses a number of characters that have not been described in other specimens of Ianthasaur us. The well-preserved maxilla and maxillary dentition, quadrate, and pterygoid contribute new anatomical information to our current understanding of the morphology of

Ianthasaur us. The adult age of the individual also provides a stronger basis for comparison with other basal synapsids. Therefore, a re-examination of its phylogenetic relationships with other members of the Edaphosauridae is warranted.

Methods and Materials

The characters used in this analysis (Appendix 1) come from a re-evaluation of the cranial anatomy of Edaphosaurus boanerges (Modesto, 1995); Modesto obtained many of his characters from data presented in Romer and Price (1940), Brinkman and Eberth (1983) and Modesto and Reisz (1992). The original data matrix for assessing the phylogenetic relationships of

Edaphosauridae (Modesto, 1995) contained 36 characters. Three new characters were added to the matrix based on information provided by ROM 59933: the first compares the maxillary marginal tooth count; the second compares of the length of the palatal ramus of the pterygoid with that of the quadrate ramus; the third quantifies the ratio of dorsal vertebral centrum length to neural spine height measured from the edge of the posterior zygopophyseal process to the tip of the spine in analogous vertebra. Measurements for these characters were made directly from ROM 59933, or culled from published measurements for the other taxa (Romer and Price,

1940; Berman, 1979; Sumida, 1979; Modesto and Reisz, 1992; Laurin, 1993). ROM 59933 also provides data for two previously unknown character states: the shape of the articular condyles of the quadrate and the presence of a pterygoid flange. In addition, four of the character states as coded by Modesto (1995) were changed because of differences in morphology observed in

ROM 59933: the shape and cutting edges present on the marginal dentition, and the presence

30 of a caniniform tooth and a caniniform region. The ingroup taxa (Modesto, 1995) are four species of Edaphosaurus (E. novomexicanus, E. cruciger, E. boanerges and E. pogonias) and

Glaucosaurus tnegalops, an edaphosaurid known from a single skull from the Lower Permian of Texas. Modesto's analysis (1994) placed Glaucosaurus at the base of the monophyletic group Glaucosaurus + Edaphosaurus based on a detailed review of the holotype. Outgroup taxa include varanopeid Mycterosaurus romeri (Berman and Reisz, 1982), ophiacodontid

Ophiacodon mirus (Williston and Case, 1913; Romer and Price, 1940) and the haptodontid

Haptodus garnettensis (Laurin, 1993).

Two additional taxa presumed to be edaphosaurids based on post-cranial characters were added

to the data matrix. The Lower Permian Texas edaphosaurid Lupeosaurus kayi was included, which is known only from post-cranial elements (Romer and Price, 1940; Reisz, 1980; Sumida,

1989). It possesses a number of characters found in other Permo-Carboniferous synapsid

genera, along with elongate neural spines which suggest it is referable to the Edaphosauridae,

although it lacks tubercles along the lateral surfaces of the spines (Sumida, 1988). It has never

been included in any published phylogenetic analysis. The second taxon is Edaphosaurus

colohistion, an edaphosaurid from the Lower Permian of West Virginia (Berman, 1978). It is

known from a series of 14 presacral vertebrae. The morphology of the vertebrae and neural

spines in both taxa suggest that they be included in Edaphosauridae, and including them in a

phylogenetic analysis will test this hypothesis and determine if the available data are sufficient to

resolve their topology within the clade.

The data matrix (Appendix 2) was constructed in MacClade 4.08 (Madison and Madison, 2005)

and all multistate characters were left unordered and unweighted. PAUP* 4.0 (Swofford, 2002)

was used to analyze the data phylogenetically utilizing a branch-and-bound algorithm with

DELTRAN character optimization. Bootstrap values were generated in PAUP* with the Branch

31 and Bound algorithm (1000 replicates); Bremer decay values were calculated in PAUP* by manually altering the maximum tree lengths, recalculating the parsimony analysis, and noting which nodes collapsed after each additional step was added. In cases where more than one most parsimonious tree (MPT) was found, a strict consensus tree was made.

Results

Five separate analyses were carried out with different combinations of taxa and characters to

assess how each change affected the previously published hypothesis of edaphosaur phylogeny.

The first analysis compared the original eight taxa from Modesto (1995) plus Ophiacodon, plus the additions and changes made to the data matrix as described earlier. As in Modesto's 1995

analysis, the result is one most parsimonious tree (Fig. 26) of 43 steps, with strong bootstrap

and Bremer values for nodes that define Edaphosaurus (A) and the most derived edaphosaurids

(B). Ianthasaurus is the sister taxon to the clade Glaucosaurus + Edaphosaurus, but is

weakly separated from Haptodus. This was not unexpected, as the basal-most species of the

Edaphosauridae and Sphenacodontidae share many primitive morphological characters (Reisz,

1980; Berman, 1998).

— Mycterosaurus

— Ophiacodon

Bootstrap — Haptodus Bremer 51 — Ianthasaurus

56 — Glaucosaurus

70 — E. novomexicanus

1 MPT _ 98 3 — E. boanerges Tree length = 52 Consistency index = .82 89 Homoplasy index = .18 — E. cruciger 95 Retention index = .9 Rescaled consistency index = .738 — E.pogonias

Figure 26: Phylogenetic analysis: Ianthasaurus & Edaphosauridae

32 A second analysis (Fig. 27) was performed after removing the two characters which describe the morphology of the marginal dentition from the matrix. This was done to take into account the disparity in the tooth morphology exhibited in the three described fossils attributed to

Ianthasaurus to compare the importance of the dental characters in the phylogenetic analysis of edaphosaurids.

Mycterosaurus

Ophiacodon

Bootstrap Haptodus Bremer 61 Ianthasaurus

68 Glaucosaurus

94 E. novomexicanus

1 MPT 96 3 E. boanerges Tree length =46 Consistency index = .8478 88 Homoplasy index = .152 E. cruciger 95 Retention index = .9163 Rescaled consistency index = .7772 E. pogonias

Figure 27: Phylogenetic analysis: Ianthasaurus & Edaphosauridae minus dental characters

In this analysis, there was no change to the single most parsimonious tree topology as the

pair of characters is ambiguous for diagnosing the Edaphosauridae, but the node between

Ianthasaurus and Glaucosaurus + Edaphosaurus has better support values (higher bootstrap and

Bremer values).

Finally, Lupeosaurus kayi and Edaphosaurus colohistion were added to the data matrix, first

individually, and then together. This was performed to determine how these two taxa, known

from incomplete morphological data, would fit with the better-known edaphosaur taxa on their

33 own, and to determine how diagnostic features that are used to define edaphosaurids (dental morphology, neural spine morphology) would affect the tree topology when being evaluated independently of other synapomorphies for the clade.

Adding Lupeosaurus to the original data matrix results in three equally parsimonious trees

(MPTs) of 51 steps (Fig. 28). The strict consensus tree recovers a polytomy of Glaucosaurus

(known from cranial data only) and Lupeosaurus (known from post-cranial data only); this demonstrates the poor resolution of phylogenies based on taxa with considerable missing data and non-overlapping morphological characters. All three MPTs found Lupeosaurus to be the sister taxon to the most derived edaphosaurids, defined by the genus Edaphosaurus (E. novomexicanus (E. boanerges (E. cruciger (E. pogonias)))).

— Mycterosaurus

— Ophiacodon

Bootstrap — Haptodus Bremer 53 — Ianthasaurus

64 — Glaucosaurus

— Lupeosaurus 68 — E. novomexicanus

Strict consensus tree of 3 MPTs 90 — E. boanerges Tree length = 51 Consistency index = .8039 88 Homoplasy index = .1961 — E. cruciger 95 Retention index = .8925 Rescaled consistency index = .7175 — E. pogonias

Figure 28: Phylogenetic analysis: Ianthasaurus & Lupeosaurus kayi

The analysis was repeated with E. colohistion replacing Lupeosaurus. The result was 6 MPTs with a length of 51 steps. The strict consensus tree (Fig. 30) yielded a polytomy of Glaucosaurus

34 + E. colohistion + E. novomexicanus + E. boanerges with no resolution except for the most basal and the most derived taxa.

Mycterosaurus

Ophiacodon

Haptodus

Ianthasaurus

Glaucosaurus

E. colohistion

E. novomexicanus Strict consensus tree of 6 MPTs Tree length = 51 E. boanerges Consistency index = .8039 Homoplasy index = .1961 E. cruciger Retention index = .8889 Rescaled consistency index = .7146 E. pogonias

Figure 29: Phylogenetic analysis: Ianthasaurus & Edaphosaurus colohistion

Berman (1979) stated that E. colohistion differs from E. novomexicanus only in being somewhat larger with greater development in the basal tubercles of the posterior cervical spines and greater cross-sectional thickening of the distal portions of the cervical spines. E. colohistion is found in Lower Permian beds of Pennsylvania and West Virginia that are chronologically just below the Cutler/Abo Lower Permian Formation of New Mexico where E. novomexicanus is found. These morphological and stratigraphic similarities suggest that E. colohistion could be a junior synonym of E. novomexicanus.

A final analysis was performed incorporating all of the taxa under consideration. Nine MPTs with a length of 52 were combined in a strict consensus tree (Fig. 30). As in the previous

35 analyses, only the node defining the most derived edaphosaurids (E. cruciger and E. pogonias) retains strong support due to the three synapomorphies: characters 23 (dentary greater than

66% of the mandibular antero-posterior length), 29 (gall-like tubercles on presacral neural

spines) and 30 (club-shaped neural spines).

Myctewsaurus

Ophiacodon

Bootstrap Haptodus Bremer 52 Ianthasaurus

62 Glaucosaurus

Lupeosaurus 62 E. novomexicanus

64 1 E. colohistion

Strict consensus tree of 9 MPTs E. boanerges Tree length = 52 53 Consistency index = .7884 E. cruciger Homoplasy index = .2115 94 Retention index = .8842 Rescaled consistency index = .6972 E. pogonias

Figure 30: Phylogenetic analysis: Ianthasaurus & Edaphosauridae, all taxa evaluated

E. colohistion and E. boanerges form a polytomy which is a sister group to E. cruciger and

E. pogonias to the exclusion of E. novomexicanus, which was unexpected if E. colohistion

is presumed to be a junior synonym of E. novomexicanus. Only one character separates E.

colohistion from E. boanerges (32), but this is based on only post-cranial data and the discovery

of cranial material attributed to E. colohistion may be necessary to resolve this. Based on the

many unresolved trees that result from the phylogenetic analysis of taxa with fragmentary or

36 incomplete evidence such as Glaucosaurus (66.7% data missing from the matrix), Lupeosaurus

(64.1% data missing) and E. colohistion (79.5% data missing), it appears that cranial or neural

spine morphology present in E. colohistion and Lupeosaurus are diagnostic for inclusion into

Edaphosauridae but both vertebral and cranial information is essential for a more accurate understanding of relationships within the clade.

37 DISCUSSION

The evolution of the modern terrestrial ecosystem, in which a population of carnivores is supported by a much larger base of herbivores or primary consumers, is one of the most significant transformations of the Permian Period (Olson, 1966). Whereas the Devonian saw the earliest vertebrate tetrapods begin to master the physical challenges of adapting to life on land, it was the advent of herbivory that allowed these animals to make the most of their new environment and the nutritional resources afforded by terrestrial plants. An appreciation of the physical characteristics and modifications of early herbivores is crucial to our understanding of this transformation.

The Edaphosauridae are one of the earliest and best known groups of early high-fiber herbivores, particularly the various species of the genus Edaphosaurus. Their isodont, peg-like

marginal dentition and batteries of tooth plates on the pterygoid and inner mandible that have

extensive wear facets leave little doubt as to their role in the processing of tough terrestrial plant matter (Reisz and Sues, 2000). In addition, their strongly curved ribs suggest that they possessed barrel-shaped bodies, resembling those of extant herbivores, which is indicative of

the voluminous gut required for the digestion of plant material. Modesto (1995) described other

traits that have a direct bearing on the presumed diet of edaphosaurs, such as the arrangement

of the marginal teeth and evidence of propaliny. However, the evolution of features specific

to herbivory is poorly understood because of the fragmentary and incomplete nature of

the fossil record of the basal members of the clade. Ianthasaurus, with its suite of primitive

eupelycosaurian and derived edaphosaurid characters, supports the hypothesis that it is a

transitional form between carnivory/insectivory and herbivory.

Tall presacral neural spines, subcircular in cross-section with lateral tubercles, are the key

diagnostic feature for the Edaphosauridae. In this regard, Ianthasaurus is clearly a member of

38 this clade. However, aspects of its cranial anatomy show certain affinities to the ecological and temporal cohabitant basal sphenacodontid haptodontids, in particular, Haptodus garnettensis.

It has been speculated that Ianthasaurus may represent a transitional form that existed at the pivotal evolutionary point between an insectivorous or carnivorous diet and herbivory

(Reisz and Berman, 1986). Reisz and Sues (2000) drew upon a number of published articles that provide evidence for support of the hypothesis that early terrestrial herbivores could have acquired the endosymbiotic microorganisms necessary for the breakdown of cellulose within the gut from the consumption of invertebrates, most likely insects. Cellulytic flora present in the gut of insects which were already digesting plants may have been passed along to the intestinal tracts of the early tetrapods that consumed them, providing the vertebrates with the ability to break down fibrous early plants on their own. Therefore, we would predict that basal edaphosaurids should possess dental morphology indicative of an insectivorous

diet. The heterodont marginal dentition and pointed, recurved teeth of the holotype KUVP

69035 certainly support this hypothesis. However, the better preserved teeth of ROM 59933

demonstrate dental morphology traits that define both insectivorous basal synapsids and

Edaphosaurus, whose success as a complete herbivore is unquestioned (King, 1996).

New data presented here support the phylogenetic position of Ianthasaurus within the

Edaphosauridae, but other critical characters are still unknown due to the fragmentary and

incomplete nature of the specimen. It is particularly unfortunate that the posterior section

of the mandible, and in particular the coronoid, was lost, and with it, diagnostic evidence for

the presence of a mandibular tooth plate. Additionally, the differences in dental morphology

between ROM 59933, and KUVP 69035 and ROM 29942 as described earlier are problematic.

One explanation maybe that elements of other synapsid taxa may have become intermingled

in the Garnett bedding plane. Based on the differences in dental morphology between ROM

39 29942 and ROM 59933, and the disassociation of skeletal elements present in ROM 29942, it is likely that the maxilla of ROM 29942 may in fact be part of another individual, probably a basal

sphenacodontid. The commingling of faunal remains is a common occurrence at this location

(Reisz and Berman, 1986). As for the differences in the mandibular marginal dentition between the holotype KUVP 69035 and ROM 59933, the position of the mandible relative to the vertebral column in KUVP 69035 supports the conclusion that it represents one individual. An explanation for the difference maybe the poor preservation of the teeth in KUVP 69035 due to

the immature status of the individual and the preservational bias against incompletely ossified tissues. It is also tempting to consider that the difference may point to an ontogenetic shift in

the marginal dentition. While this would lend support to the hypothesis that Ianthasaurus

represents a carnivorous antecedent to Edaphosaurus (Berman and Reisz, 1986; Reisz and

Modesto, 1990) this proposition remains speculative, at least until stronger evidence can be

recovered from the fossil record.

Finally, with regard to the position of Lupeosaurus in the phylogeny, the main question

continues to center on its puzzling mixture of primitive and derived basal synapsid features.

Sumida (1989) addressed this problem in his re-evaluation of the taxon and description of new

fossils attributed to the species, the first new material to be described since Romer proposed

it in 1940. He noted that despite the lack of lateral tubercles on the neural spines, one of the

synapomorphies of edaphosaurids, other morphological features such as the expansion of

the ventral plate of the clavicle, structure of the subscapulocoracoid fossa, orientation of the

neural spines, and shortening of the cervical vertebral centra relative to the dorsal vertebral

centra are shared with Edaphosaurus. Phylogenetic analysis here has shown that Lupeosaurus

is clearly a member of the Edaphosauridae. Lateral tubercles on the neural spines may have

been lost in Lupeosaurus, or it may be a species differing from the Edaphosauridae sufficiently

40 to be deserving of its own familial distinction (supported by Romer, 1940, but dismissed by

Reisz, 1980), or, as with excavated neural arches and elongated neural spines, tubercles may have evolved multiple times within Permo-Carboniferous synapsids (Reisz and Berman, 1986).

Only further fossil evidence will help to resolve the question of the phylogenetic status of

Lupeosaurus.

41 REFERENCES

Bennett, S.C. 1996. Aerodynamics and thermoregulatory function of the dorsal sail of Edaphosaurus. Paleobiology vol. 22, no. 4, pp. 496-506.

Berman, D.S. 1979. Edaphosaurus (Reptilia, Pelycosauria) from the Lower Permian of Northeastern United States, with description of a new species. Annals of Carnegie Museum vol. 48, art. 11, pp. 185-202.

Blakey, R. 2005. Paleogeography and Geologic Evolution of North America. < http://jan.ucc. nau.edu/~rcb7/RCB.html>

Brinkman, D., Eberth, D.A. 1983. The interrelationships of pelycosaurs. Breviora Number 473, 35 pp.

Case, E.C. 1908. Description of vertebrate fossils from the vicinity of Pittsburgh, Pennsylvania. Annals of Carnegie Museum vol. 4, pp. 234-241.

Cope, E.D. 1877. Descriptions of extinct Vertebrata from the Permian and Triassic formations of the United States. Transactions of the American Philosophical Society vol. 17, pp. 182- 193.

Cope, E.D. 1882. Third contribution to the history of the Vertebrata of the Permian formation of Texas. Proceedings of American Philosophical Society vol. 20, pp. 447-461.

Cope, E.D. 1884. The relations between the theromorphous Reptiles and the Monotreme Mammalia. American Association for the Advancement of Science Proceedings vol. 33, pp. 471-482.

Cope, E.D. 1886. The long-spined Theromorpha of the Permian Epoch. American Naturalist vol. 20, pp. 544-545.

Currie, P.J. 1977. A new haptodontine sphenacodont (Reptilia: Pelycosauria) from the Upper Pennsylvanian of North America. Journal of Paleontology vol. 51, no. 5, pp. 927-942.

Huttenlocker, A.K. 2008. Comparative osteohistology of hyperelongate neural spines in basal

42 synapsids (Vertebrata, Amniota): growth and mechanical considerations. Masters research paper, California State University.

Kemp, T.S. 1982. Mammal-like reptiles and the origin of mammals. London: Academic Press.

King, G. 1996. Reptiles and herbivory. London: Chapman and Hall.

Kissel, R.A., Reisz, R.R. 2004. Synapsid fauna of the Upper Pennsylvanian Rock Lake Shale near Garnett, Kansas and the diversity pattern of early amniotes. In Recent Advances in the Origin and Early Radiation of Vertebrates, ed. G. Arratia, Wilson, M.V.H., Cloutier, R., pp. 409-428. Munchen: Verlag Dr. Friedrich Pfeil.

Laurin, M. 1993. Anatomy and relationships of Haptodus garnettensis, a Pennsylvanian synapsid from Kansas. Journal of Vertebrate Paleontology vol. 13, no. 2, pp. 200-229.

Maddison, D., Maddison, W. 2005. MacClade 4: Analysis of Phylogeny and Character Evolution. Version 4.08. Sinauer Associates, Sunderland, Massachusetts.

Modesto, S.P. 1994. The Lower Permian synapsid Glaucosaurus from Texas. Palaeontology vol. 37 parti, pp. 51-60.

Modesto, S.P. 1995. The skull of the herbivorous synapsid Edaphosaurus boanerges from the Lower Permian of Texas. Palaeontology vol. 38, part 1, pp. 213-239.

Modesto, S.P., Reisz, R.R. 1990a. A new skeleton of Ianthasaurus hardestii, a primitive edaphosaur (Synapsida: Pelycosauria) from the Upper Pennsylvanian of Kansas. Canadian Journal of Earth Sciences vol. 27, no. 6, pp. 834-844.

Modesto, S.P., Reisz, R.R. 1990b. Taxonomic status of Edaphosaurus raymondi Case. Journal of Paleontology vol. 4, no. 6, pp. 1049-1051.

Modesto, S.P., Reisz, R.R. 1992. Restudy of Permo-Carboniferous synapsid Edaphosaurus novomexicanus Williston and Case, the oldest known herbivorous amniote. Canadian Journal of Earth Sciences vol. 29, pp. 2653-2662.

Osborn, H.F. 1903. On the primary division of the Reptilia into two subclasses, Synapsida and 43 Diapsida. Science vol. 17, no. 424, pp. 275-276.

Olson, E.C. 1966. Community evolution and the origin of mammals. Ecology vol. 47, no. 2, pp. 291-302.

Lane, H.H. 1945. New mid-Pennsylvanian reptiles from Kansas. Transactions of the Kansas Academy of Science, vol. 47, pp. 381-390.

Peabody, EE. 1952. Petrolacosaurus kansensis Lane, a Pennsylvanian reptile from Kansas. University of Kansas Paleontological Contributions, Vertebrata, no.l, pp. 1-41

Reisz, R.R. 1977. Petrolacosaurus kansensis Lane, the oldest known diapsid reptile. Science, 196, pp. 1091-1093

Reisz, R.R. 1980. The pelycosauria: a review of phylogenetic relationships. In The Terrestrial Environment and the Origin of Land Vertebrates, ed. A.L. Panchen, pp. 553-591. London: Academic Press.

Reisz, R.R. 1986. Pelycosauria. Edited by P. WellnhofFer. Handbuch der Palaoherpetologie. Stuttgart, New York: Gustav Fischer Verlag.

Reisz, R.R. 1990. Geology and paleontology of the Garnett Quarry. Kansas Geological Survey Report 90-24, pp. 43-48.

Reisz, R.R., Berman, D.S. 1986. Ianthasaurus hardestii n. sp., a primitive edaphosaur (Reptilia, Pelycosauria) from the Upper Pennsylvanian Rock Lake Shale near Garnett, Kansas. Canadian Journal of Earth Sciences vol.23, no. 1, pp. 77-91.

Reisz, R.R., Berman, D.S., Scott, D. 1991. The cranial anatomy and relationships of Secodontosaurus, an unusual mammal-like reptile (Synapsida: Sphenacodontidae) from the early Permian of Texas. Zoological Journal of the Linnean Society vol. 104, no. 2, pp 127 - 184

Reisz, R.R., Heaton, M.J., Pynn, B.R. 1982. Vertebrate fauna of Late Pennsylvanian Rock Lake Shale near Garnett, Kansas: Pelycosauria. Journal of Paleontology vol. 56, no. 3, pp. 741- 750.

44 Reisz, R.R., Sues, H.-D. 2000. Herbivory in Late Paleozoic and Triassic terrestrial vertebrates. In Evolution of Herbivory in Terrestrial Vertebrates: perspectives from the fossil record, ed. H.-D. Sues, pp. 9-41. Cambridge: Cambridge University Press

Romer, A.S.. 1937. New genera and species of pelycosaurian reptiles. New England Zoological Club, Pr. 16, pp. 89-96

Romer, A.S., Price, L.I. 1940. Review of the Pelycosauria. New York: Geological Society of America.

Sawin, R.S., West, R.R., Franseen, E.K., Watney, W.L., McCauley, J.R. 2006. Carboniferous- Permian Boundary in Kansas, Midcontinent, U.S.A. Current Research in Earth Sciences, Bulletin 252, part 2, pp. 1-13

Sumida, S.S. 1989. New information on the pectoral girdle and vertebral column in Lupeosaurus (Reptilia, Pelycosauria). Canadian Journal of Earth Sciences vol. 26, no. 7, pp. 1343-1349.

Sumida, S.S., Berman, D.S. 1993. The pelycosaurian (Amniota: Synapsida) assemblage from the Late Pennsylvanian Sangre de Cristo Formation of central Colorado. Annals of Carnegie Museum vol. 62, no. 4, pp. 293-310.

Swofford, D.L. 2002. PAUP* Phylogenetic Analysis Using Parsimony (*and other methods). Version 4.0M0. Sinauer Associates, Sunderland, Massachusetts.

Williston, S.W. 1915. New genera of Permian reptiles. American Journal of Science vol.4, no. 39, pp. 575-579

Williston, S.W., Case, E.C. 1913. A description of Edaphosaurus Cope. Carnegie Institute of Washington Publication no. 181, pp. 71-81.

Williston, S.W, Case, E.C. 1913. Description of a nearly complete skeleton of Ophiacodon Marsh. Carnegie Institute of Washington Publication no. 181, pp. 37-59.

Zeller, D.E. (ed.) 1968. The Stratigraphic Succession in Kansas. Vol. Bulletin 189, Kansas Geological Survey Report.

45 APPENDIX 1: CHARACTER DESCRIPTION Bracketed numbers indicate character state. Bulleted (•) characters are new. Comments are revised from Modesto (1994) and Modesto (1995).

1) Marginal teeth: taper gradually (0) or slightly bulbous (1). The marginal teeth of all Edaphosaurus species are slightly swollen distally. The teeth of the outgroup taxa taper gradually to their distal tips, and represent the plesiomorphic condition. In Modesto 1990, Ianthasaurus was coded as possessing teeth demonstrating the plesiomorphic state (0). In light of the better preserved dental morphology in ROM 59933,1 have re-coded this as a (1).

2) Marginal teeth: cutting edges are absent (0) or present (1) on mesial and distal surfaces. No cutting edges are present on the teeth of the outgroup taxa. In Modesto (1990), Ianthasaurus was coded as possessing the plesiomorphic state (0). In light of evidence seen in ROM 59933,1 have re-coded this as a (1).

3) Premaxillary dentition: larger than (0) or equal to or smaller than (1) the maxillary teeth in basal cross section. The presence of premaxillary teeth larger than maxillary teeth (except caniniforms) is primitive for eupelycosaurs. Lacking a premaxilla in any fossils of Ianthasaurus discovered to date, this character remains unknown.

4) Caniniform region: present (0) or absent (1). The presence of a caniniform region is primitive

for edaphosaurids. The maxilla and dentary of Ianthasaurus clearly shows a caniniform region.

5) Caniniform tooth: absent (0) or present (1). The presence of a caniniform tooth is primitive for edaphosaurids. Ianthasaurus is primitive in this regard, as the maxilla and mandible possess an enlarged, caniniform tooth.

6) Maxilla: long, extends past orbit (0) or short, does not extend beyond posterior

46 orbital margin (1). The derived condition diagnoses the clade Edaphosauridae + Sphenacodontidae.

7) Maxillary and dentary alveolar ridges: straight (0) or twisted (1). Vertically directed marginal dentition is considered to be plesiomorphic.

•8) Maxillary dentition: 30 to 40 tooth positions (0), 20 to 30 tooth positions (1), or less than 20 tooth positions (2). The well-preserved maxilla of ROM 59933 has positions for approximately 37 teeth.

9) Prefrontal: ventral process tongue-like (0) or expanded medially (1). The presence of a transversely slender prefrontal ventral process is plesiomorphic.

10) Frontal: lateral lappet broad (0) or narrow (1). In the primitive condition, the frontal lappet has an anterior width no less than one quarter of the frontal sagittal length. The derived state is a lappet with an antero-posterior width approximately one-ninth the frontal sagittal length.

11) Supraorbital margin: interorbital width less than the frontal sagittal length (0) or expanded laterally with an interorbital 50% greater than the frontal sagittal length (1). The broad supraorbital width seen in Edaphosaurus results in the orbits being concealed in dorsal view. The orbits are clearly visible in dorsal view due to the narrow supraorbital region in basal eupelycosaurs.

12) Parietal: in dorsal aspect, the lateral margin is straight or convex (0), or concave (1). The lateral edge of the parietal curves deeply towards the midline in Edaphosaurus in dorsal view, while in Mycterosaurus, Haptodus and Ianthasaurus, the lateral margin is either straight or convex.

13) Postorbital: contact with (0) or separate from (1) the squamosal. The posterodorsal process of the postorbital is short and does not contact the squamosal in E. boanerges, E. pogonias

47 or E. cruciger. In the outgroup taxa, the postorbital contacts the squamosal.

14) Quadratojugal: large, forming the ventral margin of the posterior cheek (0) or small, covered laterally by the squamosal. This character diagnoses the clade Edaphosauridae + Sphenacodontia (Reisz et al, 1991).

15) Quadrate: separate, distinct condyles (0) or broad, saddle-shaped articular surface (1). This character was unavailable for evaluation previously because the quadrate was unknown for Ianthasaurus. The quadrate present in ROM 59933 demonstrates the derived condition.

16) Jaw suspension: at the level of the maxillary tooth row (0), or offset ventrally from the maxillary tooth row (1). The jaw suspension at or above the level of the longitudinal axis of the upper tooth row is the primitive condition.

17) Skull: long, eight or more dorsal centra in length (0), or short, five dorsal centra or less in length. The skull of Edaphosaurus is relatively short when compared to Ianthasaurus and the outgroup taxa, whose skulls are at least eight centra long.

18) Postorbital region: shorter than the anteorbital region (0), or longer than the anteorbital region (1). In all species of Edaphosaurus, the postorbital region is shorter than the anteorbital region, and in lateral view, the orbit is centered within the skull. In Ianthasaurus and the outgroup taxa, the anteorbital region is twice the length of the anteorbital, and is interpreted as the primitive condition.

19) Pterygoid: transverse flange present (0) or absent (1). Glaucosaurus and Edaphosaurus lack a transverse flange; this character was unknown from previous specimens of Ianthasaurus.

• 20) Pterygoid: palatal ramus two times longer or greater than the length of the quadrate ramus (0), or palatal ramus less than two times the length of the quadrate ramus. The rami of the pterygoid of Ianthasaurus and the three most derived species of Edaphosaurus are approximately equal in length; this may diagnose Edaphosauridae; however, no pterygoid is

48 available for Lupeosaurus or E. colohistion, and cannot be assessed in Glaucosaurus.

21) Occluding palatal and mandibular tooth plates: absent (0) or present (1). E. boanerges, E. pogonias and E. cruciger have palatal tooth plates (formed by the palatine, pterygoid and ectopterygoid) that occlude with opposing mandibular tooth plates (formed by the anterior and posterior coronoids and prearticular). It is a synapomorphy for the most derived members of the Edaphosauridae.

22) Mandible: dorso-ventral height one quarter or less than the total length (0), or one-third or greater that the total length (l).The mandibles of E. boanerges, E. pogonias and E. cruciger are deep relative to their length, while the mandibles of the outgroup taxa are long and slender. This state cannot be determined for Glaucosaurus, E. colohistion or Lupeosaurus.

23) Dentary: comprises 70% or more of the mandibular antero-posterior length (0), or 66% or less of the mandibular antero-posterior length. The dentaries of E. boanerges, E. pogonias and E. cruciger range from 63% to 70% of the total mandibular length, while the dentaries of Haptodus and Mycterosaurus are 80% the length of their mandibles. This character cannot be determined for Ianthasaurus, Glaucosaurus, Lupeosaurus, E. novomexicanus or E. colohistion.

24) Splenial: lateral exposure one fifth or less the height of the anterior mandible (0), or one third or more the height of the anterior mandible (1). This character could not be ascertained for ROM 59933 due to the state of its current preparation.

25) Cervical centra: equal to or longer than mid-dorsal centra (0), or shorter than mid-dorsal centra (1). In Edaphosaurus, the cervical centra are shorter than the mid-dorsal centra; in Ianthasaurus they are equal; in the outgroup taxa, the cervicals are shorter than the mid- dorsal centra.

26) Presacral neural spines: short (0), or long (i.e. more than five times the height of the

49 centrum) (1). In edaphosaurids where post-cranial evidence is present, the presacral neural spines are always elongated.

• 27) Presacral neural spines: presacral centrum length to neural spine height ratio is 1:1 to 1:5 (0); ratio is 1:6 to 1:12 (1); ratio is 1:13 to 1:20 (2). This character codes for the increase in sail size relative to vertebral size seen in the most derived edaphosaurids.

28) Presacral neural spines: laterally compressed in distal cross section (0), or subcircular (1). Except for the basal-most portion, the vertebral spines of Ianthasaurus and Edaphosaurus are subcircular in cross-section. The neural spines of the outgroup taxa are blade-like.

29) Presacral neural spines: lateral tubercles absent (0), moderately-sized lateral tubercles present (1), or large, gall-like lateral tubercles present (2). The most basal of the edaphosaurids lack tubercles, or have small tubercles, along the lateral surface of their presacral vertebral spines, while the most derived members have large, gall-like projections.

30) Presacral neural spines: anterior spines are slender (0) or club-shaped (1). The distal ends of the anterior presacral neural spines in E. cruciger and E. pogonias are laterally thickened and expanded in the cranial-caudal plane to the extent that they resemble pegged clubs.

31) Neural arches: arches possess lateral excavations (0) or no excavations (1). The presence of shallow lateral excavations is plesiomorphic for eupelycosaurs. They are found in Mycterosaurus, Haptodus and Ianthasaurus (but not Ophiacodon).

32) Dorsal vertebrae: moderately developed transverse processes (0) or elongate transverse processes (1). The presence of relatively short transverse processes is plesiomorphic for eupelycosaurs.

33) Sacral and caudal vertebrae: neural spine tips are smoothly finished (0) or rugose (1). The distal tips of the sacral and neural spines in Edaphosaurus are roughened.

50 34) Sacral and caudal vertebrae: smooth sided spines (0) or spines with longitudinal ridges (1). Smooth-sided sacral and caudal vertebral spines are plesiomorphic for eupelycosaurs.

35) Caudal vertebrae: neural spines are rectangular from the lateral aspect (0), or are wider at the tip (1). The distal ends of sacral and caudal neural spines of Edaphosaurus are expanded in the sagittal plane.

36) Caudal vertebrae: neural spines are short and square (0) or tall and pointed (1). The distal tips of the caudal neural spines of Edaphosaurus are at least twice the height of the neural arch.

37) Dorsal ribs: curved proximally only (0) or curved throughout their length (1). The dorsal ribs of all species of Edaphosaurus are curved throughout their length, resulting in the barrel-shaped body that suggests the presence of a large, gas-filled gut, a hallmark of a herbivorous diet.

38) Dorsal ribs: well developed, flange-like tubercula (0) or low tuberosities (1). Prominent tubercles of bone at the heads of the dorsal ribs are plesiomorphic for eupelycosaurs.

39) Ilium: anterodorsal process smaller than posterodorsal process and convex in lateral view (0) or anterodorsal process larger that posterodorsal process and triangular in lateral view (1). The three most derived edaphosaurids (E. boanerges, E. cruciger, E. pogonias) have triangular, spade-like anterodorsal processes that are equal to the posterodorsal process in size.

51 APPENDIX 2: CHARACTER MATRIX Distribution of the character states for taxa analyzed in this paper. A question mark indicates a character missing morphological data, either from the fossil record or published descriptions.

Character number: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Mycterosaurus 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 ?

Ophiacodon 0 0 0 0 1 0 0 0 ? 1 0 0 0 0 ? 0 0 0 0 0

Haptodus 0 0 0 0 1 0 2 0 0 0 0 0 0 0 0 0 0 0

Ianthasaurus 0 0 ? 0 1 0 0 0 0 0 0 0 1 0 0 0 0

Glaucosaurus 0 0 1 1 0 0 0 2 ? 0 ?

Lupeosaurus ? ? ? ? ? ? ? ?

E. colohistion ? ? ? ? ? ? ? ?

E. novomexicanus ? ? 1 1 2 0 1 1

E. boanerges 1 1 1 0 2 1 1 1

E. cruciger 1 ? 1 0 2 1 1 1 E. pogonias 1 1 1 0 2 1 1 1

Character number: 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39

Mycterosaurus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Ophiacodon 0 0 0 0 0 0 0 0 0 0 1 0 0 ? 0 1 1 1 0

Haptodus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Ianthasaurus 0 0 0 ? 0 1 1 0 0 0 0 0 0 0 0 0 1

Glaucosaurus 0 ? ? 0 ? ? ? ? ? ? ? ?

Lupeosaurus ? ? ? 1 0 0 1 1 0 0 1

E. colohistion ? ? ? 2 1 0 ? 0 ? 1 ?

E. novomexicanus ? ? ? 1 1 0 1 1 1 1 ?

E. boanerges 1 0 1 2 1 0 1 1 1 1 1

E. cruciger 1 1 1 2 2 1 1 1 1 1 1 E. pogonias 1 1 1 2 2 1 1 1 1 1 1

52 APPENDIX 3: SUPPLEMENTAL FIGURES

13.6 mm

tooth lengths: 3.17 mm 4.36 mm 3.2 mm 3.17 mm • -3.3 mm

Figure 31: Ianthasaurus hardestiorum, left lateral maxilla measurements, ROM 59933; scale bar = 1 cm.

-5.13 mm -4.19 mm tooth lengths: 2.43 mm 3.92 mm-, r—2.72 mm

Figure 32: Ianthasaurus hardestiorum, left medial mandibular measurements, ROM 59933; scale bar = 1 cm.

53 Figure 33: Ianthasaurus hardestiorum, right quadrate and dorsal rib measurements, ROM 59933; scale bar = 1 cm.

Figure 34: Ianthasaurus hardestiorum, right pterygoid and dorsal rib measurements, ROM 59933; scale bar = 1 cm.

54 2.87 mm

132.89 mm

136.24 mm

26.94 mm

13.52 mmfl 12.38 mm

10.96 mm 11.1 mm

Figure 35: Ianthasaurus hardestiorum, left Figure 36: Ianthasaurus hardestiorum, postorbital and neural spine measurements, vertebra and neural spine measurements, ROM 59933; scale bar = 1 cm. ROM 59933; scale bar = 1 cm.

55 Figure 37: Ianthasaurus hardestiorum, caudal and presacral vertebra measurements, ROM 59933; scale bar = 1 cm.

Figure 38: Ianthasaurus hardestiorum, presacral vertebra measurements, ROM 59933; scale bar = 1 cm.

56 Figure 39: lanthasaurus hardestiorum, dorsal vertebra and rib measurements, ROM 59933; scale bar = 1 cm.

57 8.16 mm/ 6.32 mm

Figure 40: Ianthasaurus hardestiorum, dorsal ribs, cervical rib and phalangeal measurements, ROM 59933; scale bar = 1 cm.

58 Figure 41: Damaged vertebrae reconstruction

A. Pair of vertebral centra and damaged neural spine from the edge of the small piece of ROM 59933 (fig. 24)

B. Pair of damaged neural spines from the edge of the large block of ROM 59933 (fig. 12)

C. Intact pair of presacral vertebrae from the center of the large block of ROM 59933 (fig. 20), re-scaled to match A and B, for comparison;

D. Drawing A has been flipped and added to B to demonstrate that the pieces match up and are consistent in size with the other pair of complete vertebrae.

Scale bar = 1 cm.

59 APPENDIX 4: PAUP* DATA P A U P * Version 4.0bl0 for Macintosh (PPQ Sunday, August 24, 2008 10:32 AM

Data matrix has 11 taxa, 39 characters Valid character-state symbols: 012 Missing data identified by '?' Gaps identified by '-'

Taxa analysed: Mycterosaurus Ophiacodon Haptodus Ianthasaurus Glaucosaurus E. novomexicanus E. boanerges E. cruciger E. pogonias

Branch-and-bound search settings: Optimality criterion = parsimony Character-status summary: Of 39 total characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Initial upper bound: unknown (compute heuristically) Addition sequence: furthest Initial 'MaxTrees' setting = 1000 (will be auto-increased by 100) Branches collapsed (creating polytomies) if maximum branch length is zero 'MulTrees' option in effect Topological constraints not enforced Trees are unrooted

Branch-and-bound search completed: Score of best tree found = 50 Number of trees retained = 1 Time used =0.02 sec

Tree description: Unrooted tree(s) rooted using outgroup method Optimality criterion = parsimony Character-status summary: Of 39 total characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Character-state optimization: Delayed transformation (DELTRAN)

Tree number 1 (rooted using user-specified outgroup) Tree length = 50 Consistency index (CI) = 0.8200 Homoplasy index (HI) = 0.1800 Retention index (RI) = 0.9000 Rescaled consistency index (RC) = 0.7380

60 / Mycterosaurus I I / Ophiacodon I I \ + / Haptodus I I Ianthasaurus \ + / I I Glaucosaurus \ + / I I / E_ novomexicanus \ + I I + / £. boanerges I I \ + / £_ cruciger \ + \ E. pogonias

Character change lists:

Character CI Steps Changes 1 (marginal teeth: taper gradually) 0.500 1 node_16 0 --> 1 Ianthasaurus 1 node_15 0 —> 1 node_14 2 (marginal teeth: cutting edges a) 0.500 1 node_16 0 --> 1 Ianthasaurus 1 node_14 0 —> 1 node_13 3 (premax dentition: > than (0) or) 1.000 1 node_16 0 —> 1 node_15 4 (caniniform region: present (0) ) 1.000 1 node_16 0 ==> 1 node_15 1 node_18 0 ==> 1 Ophiacodon 5 (caniniform teeth: absent (0) or) 0.500 1 node_16 0 ==> 1 node_15 1 node_18 0 ==> 1 node_17 6 (maxilla: long, extends past orb) 0.500 1 node_15 1 ==> 0 Glaucosaurus 1 node_15 0 ==> 1 node_14 7 (maxilla & dentary alveolar ridg) 1.000 1 Mycterosaurus 1 ==> 0 node_18 8 (maxilla tooth positions: 21+ (0) 0.500 1 node_16 0 ==> 1 node_15 9 (prefrontal: ventral percess ton) 1.000 1 node_16 0 ==> 1 node_15 10 (frontal: lat. lappet broad (0)) 1.000 1 node_14 0 ==> 1 node_13 11 (supraorbital margin: weakly de) 1.000 1 node_15 0 ==> 1 node_14 12 (parietal: lat. margin straight) 1.000 1 node_15 0 --> 1 node_14 13 (postorbital: contacts squamosa) 1.000 1 node_14 0 —> 1 node_13 14 (quadratojugal: large, forms ve) 1.000 1 node_18 0 ==> 1 node_17 15 (quadrate: condyles distinct (0) 1.000 1 node_17 0 ==> 1 node_16 16 (jaw suspension: level of max. ) 1.000 1 node_15 0 —> 1 node_14 17 (skull: long/ 8 or more dorsal ) 1.000 1 node_15 0 —> 1 node_14 18 (postorbital: shorter (0) or lo) 1.000 1 node_15 0 --> 1 node_14 19 (pterygoid: transverse flange p) 1.000 node_16 0 == > 1 node_15 20 (pterygoid: long palatal ramus=) 1.000 1 node_17 0 ==> 1 node_16 21 (tooth plates: absent (0) or pr) 1.000 1 node_15 0 ==> 1 node_14 22 (mandible: dorso-ventral height) 1.000 1 node_14 0 —> 1 node_13 23 (dentary: 70% > (0), or 66%< of) 1.000 1 node_13 0 ==> 1 node_12 24 (splenial: lat. exposure 1/5 or) 1.000 1 node_14 0 --> 1 node_13 25 (cervical centra: = to (0) or s) 1.000 1 node_15 0 --> 1 node_14 26 (presacral neural spines: short) 1.000 1 node_17 0 ==> 1 node_16 27 (presacral centrum length to ne) 1.000 1 node_17 0 ==> 1 node_16 1 node_14 1 ==> 2 node_13 28 (presacral neural spines: lat. ) 1.000 1 node_17 0 ==> 1 node_16 29 (presacral neural spines: later) 1.000 1 node_17 0 ==> 1 node_16 1 node_13 1 ==> 2 node_12 30 (presacral neural spines: anter) 1.000 1 node_13 0 ==> 1 node_12 31 (neural arches: excavated (0) o) 0.500 1 node_18 0 ==> 1 Ophiacodon 1 node_15 0 —> 1 node_14 32 (dorsal vertebrae: transverse p) 1.000 1 node_15 0 --> 1 node_14 33 (sacral and caudal vertebrae: n) 1.000 1 node_15 0 --> 1 node_14 34 (sacral and caudal vertebrae: s) 1.000 1 node_15 0 --> 1 node_14 35 (caudal vertebrae: neural spine) 1.000 1 node_15 0 --> 1 node_14 36 (caudal vertebrae: neural spine) 0.500 1 node_18 0 ==> 1 Ophiacodon 1 node_15 0 —> 1 node_14 37 (dorsal ribs: curved proximally) 0.500 1 node_18 0 ==> 1 Ophiacodon

61 node_15 0 --> 1 node_14 38 (dorsal ribs: well developed, f) 0.500 node_18 0 ==> 1 Ophiacodon node_15 0 --> 1 node_14 39 Cillurn: anterodorsal proc. < po) 1.000 node_17 0 ==> 1 node_16

Bootstrap method with branch-and-bound search: Number of bootstrap replicates = 1000 Starting seed = 1821793742 Optimality criterion = parsimony Character-status summary: Of 39 total characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Initial upper bound: unknown (compute heuristically) Addition sequence: furthest Initial 'MaxTrees' setting = 1000 (will be auto-increased by 100) Branches collapsed (creating polytomies) if maximum branch length is zero 'MulTrees' option in effect Topological constraints not enforced Trees are unrooted Bootstrap replicates completed Time used =2.23 sec

Bipartitions found in one or more trees and frequency of occurrence (bootstrap support values): 11 123458901 Freq % **** 977.76 97.8% ** 960.14 96.0% **# 890.27 89.0% ***** 711.04 71.1% ****** 573.42 57.3% . ******* 478.33 47.8% * **** 285.15 28.5% ** **** 215.33 21.5% * ***** 193.70 19.4% * ****** 131.46 13.1% .***.**** 106.47 10.6% * * 96.87 9.7% .**.... 90.01 9.0%

11 groups at (relative) frequency less than 5% not shown

Character-exclusion status changed: 2 characters excluded (marginal dentition) Number of included characters = 37

Branch-and-bound search settings: Optimality criterion = parsimony Character-status summary: 2 characters are excluded Of the remaining 37 included characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Initial upper bound: unknown (compute heuristically) Addition sequence: furthest Initial 'MaxTrees' setting = 1000 (will be auto-increased by 100) Branches collapsed (creating polytomies) if maximum branch length is zero

62 'MulTrees' option in effect Topological constraints not enforced Trees are unrooted Branch-and-bound search completed: Score of best tree found = 46 Number of trees retained = 1 Time used =0.02 sec Tree description: Unrooted tree(s) rooted using outgroup method Optimality criterion = parsimony Character-status summary: 2 characters are excluded Of the remaining 37 included characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Character-state optimization: Delayed transformation (DELTRAN) Tree number 1 Crooted using user-specified outgroup) Tree length = 46 Consistency index (CI) = 0.8478 Homoplasy index (HI) = 0.1522 Retention index (RI) = 0.9167 Rescaled consistency index (RC) = 0.7772

Mycterosaurus /- Ophiacodon I -+ Haptodus I \- Ianthasaurus Glaucosaurus E. novomexicanus E. boanerges E. cruciger E. pogonias

Bootstrap method with branch-and-bound search: Number of bootstrap replicates = 1000 Starting seed = 524823568 Optimality criterion = parsimony Character-status summary: 2 characters are excluded Of the remaining 37 included characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Initial upper bound: unknown (compute heuristically) Addition sequence: furthest ' Initial 'MaxTrees' setting = 1000 (will be auto-increased by 100) Branches collapsed (creating polytomies) \f maximum branch length is zero 'MulTrees' option in effect Topological constraints not enforced Trees are unrooted Bootstrap replicates completed Time used =2.13 sec

63 Bipartitions found in one or more trees and frequency of occurrence (bootstrap support values):

11 123458901 Freq % **** 969.77 97.0% >(c $ % $ $ 939.71 94.0% ** 936.66 93.7% *** 885.32 88.5% .. ****** 704.74 70.5% ******* 613.06 61.3% .*._***** 237.39 23.7% if. if if Hi Ht 3|c3|c 147.58 14.8% ** 109.27 10.9% $ ififUf^t 55.43 5.5% ** **** 54.29 5.4% 19 groups at (relative) frequency less than 5% not shown

Taxon status changed: Lupeosaurus kayi added Number of taxa = 10 All characters evaluated Branch-and-bound search settings: Optimality criterion = parsimony Character-status summary: Of 39 total characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Initial upper bound: unknown (compute heuristically) Addition sequence: furthest Initial 'MaxTrees' setting = 1000 (will be auto-increased by 100) Branches collapsed (creating polytomies) if maximum branch length is zero 'MulTrees* option in effect Topological constraints not enforced Trees are unrooted

Branch-and-bound search completed: Score of best tree found = 51 Number of trees retained = 3 Time used =0.02 sec

Tree description: Unrooted tree(s) rooted using outgroup method Optimality criterion = parsimony Character-status summary: Of 39 total characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Character-state optimization: Delayed transformation (DELTRAN) Tree number 1 (rooted using user-specified outgroup)

Tree length = 51 Consistency index (CI) = 0.8039 Homoplasy index (HI) = 0.1961 Retention index (RI) = 0.8925 Rescaled consistency index (RC) = 0.7175

64 Mycterosaurus Ophiacodon

-+ Haptodus I \- -+ Ianthasaurus I \- / Glaucosaurus Lupeosaurus novomexicanus boanerges cruciger pogonias Tree number 2 (footed using user-specified outgroup) Tree length = 51 Consistency index (CI) = 0.8039 Homoplasy index (HI) = 0.1961 Retention index (RI) = 0.8925 Rescaled consistency index (RC) = 0.7175 Mycterosaurus Ophiacodon Haptodus Ianthasaurus Glaucosaurus Lupeosaurus novomexicanus boanerges cruciger pogonias

65 Tree number 3 (rooted using user-specified outgroup)

Tree length = 51 Consistency index (CI) = 0.8039 Homoplasy index (HI) = 0.1961 Retention index (RI) = 0.8925 Rescaled consistency index (RQ 0.7175

/- Mycterosaurus Ophiacodon I I Haptodus \- /- Ianthasaurus I I Glaucosaurus I -+ / E. novotnexicanus I I I /- E. boanerges I I V \- -+ E. cruciger \- I E. pogonias I \- Lupeosaurus Strict consensus of 3 trees: Mycterosaurus Ophiacodon Haptodus Ianthasaurus

Glaucosaurus Lupeosaurus

novomexicanus boanerges cruciger pogonias Bipartitions found in one or more trees and frequency of occurrence: 11 1234568901 Freq % ******** 3 100.0% ******* 3 100.0% ****** 3 100.0% **** 3 100.0% 3 100.0% . . ** ***** 3 100.0% 1 33.3% ** 1 33.3% 1 33.3%

Bootstrap method with branch-and-bound search: Number of bootstrap replicates = 1000

66 Starting seed = 228566631 Optimality criterion = parsimony Character-status summary: Of 39 total characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Initial upper bound: unknown (compute heuristically) Addition sequence: furthest Initial 'MaxTrees' setting = 1000 (will be auto-increased by 100) Branches collapsed (creating polytomies) if maximum branch length is zero 'MulTrees' option in effect Topological constraints not enforced Trees are unrooted

Bootstrap replicates completed Time used =3.12 sec

Bipartitions found in one or more trees and frequency of occurrence (bootstrap support values): 11 1234568901 Freq % ** 947.89 94.8% **** 914.12 91.4% _*** 890.02 89.0% ** ** ** 682.96 68.3% Hi****** 652.29 65.2% ******** 549.82 55.0% ***** 524.46 52.4% 271.73 27.2% * **** 257.32 25.7% ** ***** 202.00 20.2% ** 201.39 20.1% 128.37 12.8% * ******* 121.29 12.1% * * 104.10 10.4% 84.38 8.4% ** 52.87 5.3% 31 groups at (relative) frequency less than 5% not shown

Taxon status changed: E. colohition added Lupeosaurus kayi removed Number of taxa = 10

Branch-and-bound search settings: Optimality criterion = parsimony Character-status summary: Of 39 total characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Initial upper bound: unknown (compute heuristically) Addition sequence: furthest Initial 'MaxTrees' setting = 1000 (will be auto-increased by 100) Branches collapsed (creating polytomies) if maximum branch length is zero 'MulTrees' option in effect Topological constraints not enforced Trees are unrooted Branch-and-bound search completed:

67 Score of best tree found = 51 Number of trees retained = 6 Time used = 0.02 sec Tree number 1 (footed using user-specified outgroup) / Mycterosaurus Ophiacodon Haptodus Ianthasaurus Glaucosaurus colohistion /- novomexicanus I -+ boanerges I \- -+ cruciger \- pogonias Tree number 2 (footed using user-specified outgroup) / Mycterosaurus Ophiacodon I Haptodus -+ I Ianthasaurus \- Glaucosaurus E. colohistion E. novomexicanus E. boanerges

-+ E. cruciger \- E. pogonias Tree number 3 (rooted using user-specified outgroup) Mycterosaurus Ophiacodon Haptodus Ianthasaurus Glaucosaurus /- E. novomexicanus I I /- E. boanerges I I -+ -+ /- E. cruciger I \- -+ I \- E. pogonias I V E. colohistion

68 Tree number 4 (rooted using user-specified outgroup) / Mycterosaurus Ophiacodon Haptodus Ianthasaurus Glaucosaurus I E. colohistion I -+ -+ E. cruciger I \- -+ I /- \- E. pogonias I I \- -+ E. boanerges I \- E. novomexicanus Tree number 5 (footed using user-specified outgroup) /- Mycterosaurus I I Ophiacodon I I Haptodus V Ianthasaurus /- Glaucosaurus I I / E. colohistion I I -+ I + E, boanerges I -+ I I / E. cruciger \- \ + \ E. pogonias E. novomexicanus Tree number 6 (rooted using user-specified outgroup) / Mycterosaurus I I / Ophiacodon I I Haptodus I | / \ + I Ianthasaurus -+ I Glaucosaurus \- E. colohistion E. boanerges E. cruciger E. pogonias E. novomexicanus

69 Strict consensus of 6 trees: / Mycterosaurus Ophiacodon I I Haptodus \- Ianthasaurus Glaucosaurus E. colohistion + I + £# novomexicanus -+ E. boanerges + E. cruciger E. pogonias Strict consensus of 6 trees Mycterosaurus Ophiacodon I /- Haptodus -+ I I I Ianthasaurus \- -+ I Glaucosaurus I \- E. colohistion + I + E, novomexicanus -+ + £t boanerges E. cruciger E. pogonias

Bipartitions found in one or more trees and frequency of occurrence: 11 1234578901 Freq % ******** 6 100.0% ******* 6 100.0% ****** 6 100.0% ** 6 100.0% ***** 4 66.7% *** 4 66.7% **** 3 50.0% * *** 3 50.0% ** 1 16.7% * **** 1 16.7% * ** 1 16.7%

All taxa analysis: Mycterosaurus Ophiacodon Haptodus

70 Ianthasaurus Glaucosaurus Lupeosaurus E. colohistion E. novomexicanus E. boanerges E. cruciger E. pogonias Branch-and-bound search settings: Optimality criterion = parsimony Character-status summary: Of 39 total characters: All characters are of type 'unord' All characters have equal weight All characters are parsimony-informative Gaps are treated as "missing" Initial upper bound: unknown (compute heuristically) Addition sequence: furthest Initial 'MaxTrees' setting = 1000 (will be auto-increased by 100) Branches collapsed (creating polytomies) if maximum branch length is zero 'MulTrees' option in effect Topological constraints not enforced Trees are unrooted Branch-and-bound search completed: Score of best tree found = 52 Number of trees retained = 9 Time used = 0.02 sec

Tree number 1 (rooted using user-specified outgroup) / Mycterosaurus I I / Ophiacodon I I I | / Haptodus \ + I I | / Ianthasaurus \ + I I | / Glaucosaurus \ + I I | / Lupeosaurus \ + I I | / E# colohistion I I I \ + / + / E. boanerges I I I I I | \ + / E. cruciger \ + \ + I \ E. pogonias I \ E. novomexicanus

71 Tree number Z (rooted using user-specified outgroup) /- Mycterosaurus I I Ophiacodon I I Haptodus \- Ianthasaurus Glaucosaurus Lupeosaurus colohistion boanerges cruciger pogonias novomexicanus Tree number 3 (rooted using user-specified outgroup) / Mycterosaurus Ophiacodon Haptodus -+ I /- Ianthasaurus I I \- I Glaucosaurus I I E. colohistion -+ I E. boanerges I I E. cruciger I \- E. pogonias E. novomexicanus Lupeosaurus Tree number 4 (rooted using user-specified outgroup) / Mycterosaurus Ophiacodon /- Haptodus I I Ianthasaurus -+ I Glaucosaurus \- Lupeosaurus

/- E. colohistion I +- E. boanerges -+ I E. cruciger \- E. pogonias E. novomexicanus

72 Tree number 5 (rooted using user-specified outgroup) Mycterosaurus I /- Ophiacodon I I I I Haptodus \- -+ I Ianthasaurus \- Glaucosaurus /- I Lupeosaurus I I /- E. colohistion I I -+ +- E. boanerges I -+ I I /- E. cruciger I \- -+ \- \- E. pogonias E. novomexicanus Tree number 6 (rooted using user-specified outgroup) Mycterosaurus Ophiacodon Haptodus /- Ianthasaurus I / Glaucosaurus I I colohistion -+ I /- boanerges I I /- I I I cruciger I I I \- -+ -+ pogonias I I I \- novomexicanus I \- Lupeosaurus Tree number 7 (rooted using user-specified outgroup) / Mycterosaurus Ophiacodon Haptodus -+ I Ianthasaurus \- Glaucosaurus -+ I /- Lupeosaurus \- -+ I I I E. colohistion I I \- -+ /- E. cruciger I -+ \- E. pogonias E. boanerges E. novomexicanus

73 Tree number 8 (rooted using user-specified outgroup) Mycterosaurus Ophiacodon /- Haptodus I I Ianthasaurus -+ I Glaucosaurus I \- -+ Lupeosaurus I I E. colohistion I \- E. cruciger /- E. pogonias I -+ E. boanerges I \- E. novomexicanus Tree number 9 (rooted using user-specified outgroup) Mycterosaurus Ophiacodon Haptodus Ianthasaurus Glaucosaurus colohistion cruciger pogonias boanerges novomexicanus Lupeosaurus Strict consensus of 9 trees: Mycterosaurus Ophiacodon Haptodus Ianthasaurus Glaucosaurus Lupeosaurus E. colohistion -+ I E. boanerges I I E. cruciger I V E. pogonias E. novomexicanus

74 Bipartitions found in one or more trees and frequency of occurrence (bootstrap support values): 11 12345678901 Freq ** 932.09 93.2% ******** 653.82 65.4% ******* 637.37 63.7% ___***** 604.46 60.4% ********* 553.30 55.3% .*.*** 551.36 55.1% ...*** 530.95 53.1% ****** 416.90 41.7% _**** 274.57 27.5% ****** 241.22 24.1% ***** 239.94 24.0% .***** 207.83 20.8% ******** 182.62 18.3% .** 169.13 16.9% .**.**** 141.52 14.2% ******** 138.85 13.9% ...*..** 133.24 13.3% ******* 130.58 13.1% ********.* * 94.480.452 8.09.4% ...*..**** 54.32 5.4% 62 groups at (relative) frequency less than 5% not shown

75