Analysis of North American goniopholidid crocodyliforms in a phylogenetic context

Transcription

1 University of Iowa Iowa Research Online Theses and Dissertations Summer 2012 Analysis of North American goniopholidid crocodyliforms in a phylogenetic context Eric Randall Allen University of Iowa Copyright 2012 Eric Randall Allen This thesis is available at Iowa Research Online: Recommended Citation Allen, Eric Randall. "Analysis of North American goniopholidid crocodyliforms in a phylogenetic context." MS (Master of Science) thesis, University of Iowa, Follow this and additional works at: Part of the Geology Commons

2 ANALYSIS OF NORTH AMERICAN GONIOPHOLIDID CROCODYLIFORMS IN A PHYLOGENETIC CONTEXT by Eric Randall Allen A thesis submitted in partial fulfillment of the requirements for the Master of Science degree in Geoscience in the Graduate College of The University of Iowa July 2012 Thesis Supervisor: Associate Professor Christopher Brochu

3 Copyright by ERIC RANDALL ALLEN 2012 All Rights Reserved

4 This is to certify that the Master s thesis of Graduate College The University of Iowa Iowa City, Iowa CERTIFICATE OF APPROVAL MASTER S THESIS Eric Randall Allen has been approved by the Examining Committee for the thesis requirement for the Master of Science degree in Geoscience at the July 2012 graduation. Thesis Committee: Christopher Brochu, Thesis Supervisor Jonathan Adrain Llewellyn D. Densmore

5 To my wife ii

6 ACKNOWLEDGMENTS I wish to thank my advisor, C. Brochu, and my Comprehensive Exam committee, J. Adrain, A. Budd, J. Logsdon, and H. Sims. For discussion and help preparing this manuscript I would like to thank E. Allen, S. Salisbury, E. Wilberg, and the University of Iowa VertPaleo discussion group: S. Drumheller, M.E. Gold, A. Grass, J. McHugh, J. Miller-Camp, J. Nestler, and M. Spencer. For access to collections and specimens, I wish to thank J. Conrad and C. Mehling (American Museum of Natural History), A. Henrici (Carnegie Museum of Natural History), W. Langston Jr. (University of Texas at Austin), D. Main (University of Texas at Arlington), L. Steel (British Natural History Museum), and J. Person (Sam Noble Museum of Natural History). Finally, I wish to thank A. Pritchard for allowing access to unpublished data. This research was funded in part by the Max and Lorraine Littlefield Fund. iii

7 TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF ABBREVIATIONS vi vii viii CHAPTER 1 OSTEOLOGY OF AMPHICOTYLUS STOVALLI AND COMMENTS ON GONIOPHOLIDIDS OF THE MORRISON FORMATION 1 Introduction 1 Systematic Paleontology 2 Description of Material 3 Form and condition 3 Skull Openings 3 Cranial Elements 5 Discussion 10 Comparison to other taxa 10 Status of Morrison Formation goniopholidids 12 2 NEW MATERIAL OF THE MANDIBLE OF DENAZINOSUCHUS KIRTLANDICUS 18 Introduction 18 Systematic Paleontology 19 Description of Material 20 Observations from the holotype 20 Description of new material 20 Discussion 23 3 PHYLOGENETIC ANALYSIS OF GONIOPHOLIDIDAE 27 Introduction 27 Status of goniopholidid phylogenetics 28 Phylogenetic Analysis 29 Taxon sampling and dataset 29 Results 30 General results and North American goniopholidids 30 Denazinosuchus and Vectisuchus 32 Discussion 33 Biostratigraphy 34 Conclusions 35 iv

8 APPENDIX A LIST OF CHARACTERS 42 APPENDIX B DATA MATRIX USED IN PHYLOGENETIC ANALYSIS 62 APPENDIX C CHARACTER TRANSITIONS 73 REFERENCES 79 v

9 Table LIST OF TABLES 1. Compilation of Morrison Formation goniopholidids 14 vi

10 LIST OF FIGURES Figure 1. Example of an extant crocodyliform OMNH 2392 Amphicotylus stovalli, dorsal aspect OMNH 2392 Amphicotylus stovalli, ventral aspect PMU.R 232 Denazinosuchus kirtlandicus holotype New material referred to Denazinosuchus kirtlandicus Summary of phylogenetic placements of Goniopholididae Phylogenetic results of entire dataset Detail of cladograms investigating relationships within Goniopholididae Detail of cladogram if Arlington Form excluded from analysis Stratigraphically calibrated cladogram of selected taxa 41 vii

11 LIST OF ABBREVIATIONS Institutions: AMNH, American Museum of Natural History, New York, New York; BYU, Brigham Young University, Provo, Utah; CM, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania; CMNH, Cleveland Museum of Natural History, Cleveland, Ohio; NMMNH, New Mexico Museum of Natural History and Science, Albuquerque, New Mexico; OMNH, Sam Noble Museum of Natural History, Norman, Oklahoma; PMU.R, Paleontological Museum, University of Uppsala, Uppsala, Sweeden. TMM, Texas Natural Science Center, University of Texas at Austin; YPM, Yale Peabody Museum, New Haven, Connecticut. Anatomical Terms: Fr: frontal Jg: jugal La: lacrimal Mx: maxilla N: nasal Pa parietal Pal: palatine Po: postorbital Pf: prefrontal Pm: premaxilla Q: quadrate Qj: quadratojugal Sq: squamosal viii

12 1 CHAPTER 1 OSTEOLOGY OF AMPHICOTYLUS STOVALLI AND COMMENTS ON GONIOPHOLIDIDS OF THE MORRISON FORMATION Introduction Crocodyliformes is a large, diverse group of archosaurs including extant crocodylians their fossil relatives. Though all living crocodyliforms are of relatively conserved morphology (Fig. 1), historically the clade was considerably more disparate, including even fully terrestrial and secondarily marine taxa. Goniopholididae constitutes some of the most common, widespread, and distinctive crocodyliforms of the Late Jurassic and Early Cretaceous. These neosuchians are among the first crocodyliform taxa to superficially resemble modern crocodylians, and are presumed to have occupied a similar ecological role (Schwarz, 2002; Buffetaut, 1982). Goniopholidids were widespread throughout Laurasia during the Late Jurassic and Early Cretaceous, and are frequently found in freshwater or estuarine deposits (Hups et al., 2006). The majority of Goniopholis species are known from the United Kingdom, but also occur in continental Europe, particularly in the north and west (Owen 1842, , 1878, 1879; Hulke, 1878; Dollo, 1883; Koken 1883, 1886, 1887, 1896; Hooley,1907; Edinger, 1938; Jonet, 1981; Huckriede, 1982; von Oekentorp, 1984; Buffetaut, 1986; Norman, 1987; Buscalioni & Sanz, 1987a, b; Buffetaut et al., 1989; Cuny et al., 1991; Ortega et al., 1996; Salisbury et al., 1999; Salisbury, 2002; Schwarz, 2002; Schwarz-Wings et al., 2009; Salisbury & Naish, 2011). Goniopholidids have also been reported from Asia (Young, 1948; Buffetaut & Ingavat, 1980, 1983; Wu et al, 1996; Maisch et al., 2003) and North America (Marsh, 1877; Cope, 1878; Holland, 1905; Wiman, 1932; Mook, 1964, 1967; Tykoski et al., 2002). They are united in general by (1) nasals which do not participate in the narial border; (2) amphicoelous vertebrae; (3) two rows of rectangular, imbricated paravertebral osteoderms with rostrally-directed articular spine on the rostrolateral margin; (4) choanae bound caudally by the pterygoid and anteriorly by the

13 2 palatine; (5) the presence of a maxillary fossa on the caudolateral margin of the maxilla. This maxillary fossa is enigmatic, but it does lie in line with the line of neurovascular foramina on the lateral surface of the maxilla, and may thus represent a region of hyperenlarged foramina (De Andrade, 2009). The Upper Jurassic Morrison Formation accounts for the most specimens and largest number of reported species in North America with five taxa currently recognized. Furthermore, all North American taxa attributed to Goniopholis Owen, 1841 are known from the Morrison (Table 1). This provides a unique opportunity to investigate Goniopholididae in North America and the affinity of Goniopholis identified on that continent and Europe. Amphicotylus stovalli is a comparatively well-represented Morrison Formation goniopholidid with two well-preserved skulls and considerable attributed postcrania. The original material for A. stovalli was excavated by the Works Progress Administration in the 1930s in Cimarron County, Oklahoma and initially investigated by J. W. Stovall, who noted overall similarity to A. gilmorei (Mook, 1964). The material was first described by Mook (1964) who ascribed it to Goniopholis Owen, Unfortunately, the initial, and preliminary, description lacked considerable detail. This study redescribes the type material of Amphicotylus stovalli and investigates Abbreviations AMNH, American Museum of Natural History, New York, New York; BYU, Brigham Young University, Provo, Utah; CM, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania; CMNH, Cleveland Museum of Natural History, Cleveland, Ohio; OMNH, Sam Noble Museum of Natural History, Norman, Oklahoma; TMM, Texas Natural Science Center, University of Texas at Austin; YPM, Yale Peabody Museum, New Haven, Connecticut. Systematic Paleontology CROCODYLIFORMES Hay, 1930 MESOEUCROCODYLIA Whetstone and Whybrow, 1983

14 3 GONIOPHOLIDIDAE Cope, 1875 AMPHICOTYLUS Cope, 1878 AMPHICOTYLUS STOVALLI (Mook, 1964) (Figs. 2-3) Holotype OMNH 2392; near-complete articulated skull. Paratype OMNH 2322; near-complete articulated skull. Horizon and Locality Jurassic (?Kimmeridgian), Morrison Formation, Locality V97 (Kenton 8), Cimarron County, Oklahoma. Revised Diagnosis A goniopholidid crocodyliform with constricted figureeight external naris, subtriangular lacrimal, frontal which participates in the orbit, and a narrow, channel-like internal choanae completely separating the pterygoids and bounded anteriorly by the maxilla, caudally by the pterygoid, and not extending caudal to the orbits. Description of Material Form and condition All observations are from OMNH 2392, a near-complete, articulated skull, with supplemental observations from OMNH Quality of preservation is very good on both specimens. OMNH 2392 is slightly crushed dorsoventrally, particularly the caudal portions, and slightly skewed to the left. The snout region is in very good condition with some slight damage along the lateral margins. The occipital condyle is broken off. In ventral aspect, the braincase caudal to the orbits is badly crushed, especially on the left. Skull openings The external nares are confluent along the midline of the skull. In dorsal aspect, the aperture is shaped like a broad figure eight due to midline protrusions of the premaxille into the narial border from both the rostral and caudal margins. The nares are directed dorsally and entirely contained within the premaxillae. Anterior and posteriolateral margins are slightly vaulted.

15 4 This posterior palatine vacuity is large and ovoid in shape, acute rostrally. The rostral and lateral margins are bound by the maxilla, and medially by the palatine. The opening extends rostrally to beneath the maxillary fossae. In dorsal aspect, the orbit is a subrectangular ellipse elongated rostrocaudally. Due to distortion of the skull, the left orbit appears triangular in shape. It is bound by the lacrimal, prefrontal, and frontal(?) medially, the postorbital caudally, and the jugal laterally. The supratemporal fenestra is nearly circular. The rostral and caudal margins are slightly elevated. The margins only slightly overhang the recessus supratemporales, particularly along the anterior margin. The foramen is bounded by the squamosal caudolaterally, the postorbital rostrolaterally, the frontal rostromedially, and the parietal caudomedially. The infratemporal fenestra is oblong, over twice as long as it is high. A broad processus infratemporalis of the quadratojugal, inserting approximately halfway along the occipital margin bifurcates that margin. The fenestra is bound by the jugal rostroventrally, the postorbital rostrodorsally, the squamosal dorsally, and the quadratojugal caudoventrally. The internal choanae form a deep, narrow channel 55mm long and 15mm wide along the midline of the palate, completely separating the palatines. The rostral margin is formed by the posterior margin of the maxillae and the caudal and caudolateral margins are formed by the pterygoids. A thin septum is partially preserved running the length of the opening. The posttemporal fenestra has been destroyed on both specimens due to dorsoventral crushing, though its position may still be noted. This foramen would be a very long but not very high slit-like opening bounded dorsally by the parietal and squamosal and ventrally by the supraoccipital and otoccipital ventrally. It is visible only is occipital aspect.

16 5 The medial Eustachian opening is a small, circular opening on the ventral surface of the braincase directly between the basioccipital and basisphenoid. It appears to have possibly been artificially widened during preparation. Cranial elements Premaxilla In dorsal aspect, the premaxillae are as wide as the rostral portions of the maxillae. The rostral portion is spatulate in shape and the external nares are located 20mm from the rostral-most margin. They are convex laterally and indented caudally be a deep notch for reception of a large dentary pseudocanine. Caudal to this notch, they extend caudally medial to the macillae to contact the nasals about even with the lateral swelling of the maxilla over the maxillary pseudocanines. Dorsoventral crushing of the snout has slightly separated the premaxillae from the maxillae along this suture. The dorsal, medial, and lateral portions are sculptured with indistinct rugosities and shallow circular pits 2-3mm in diameter. The rostral margin is not sculptured, but is perforated by two 4mm wide holes which are inferred as wear-holes to accept the rostral-most dentary teeth. Ventrally, these pits lie in the rostral portion of the nasal vestibule and are 18mm apart. In vertral aspect, the caudal margin of the premaxillae forms a broad U-shape, convex rostrally, from the caudal notch to within 7mm of the caudal margin of the nasal vestibule. Five alveoli are present. A partially-erupted tooth crown is visible in the 4 th alveolus on both the left and right elements. A small, 4mm long and 5mm wide triangular anterior palatine vacuity lies at the caudal midline, at the juncture with the midline of the maxillae. Two small 4mm wide pits lie along the premaxilla/maxilla suture lateral to this vacuity. These pits can be viewed in the occipital portion of the external nares. Their nature is unclear, as they are too medial to be considered tooth-reception pits. Maxilla The Maxillae form the majority of the snout and secondary palate. The lateral margin is convex over the 4 th and 5 th alveoli, becoming broadly concave caudally.

17 6 The dorsal and lateral surfaces are sculptured by indistinct pits and rugosities oriented roughly rostrocaudally. A shallow, oblong depression on the caudolateral margin marks the mandibular fossa. The rostral margin of the depression is marked by a broad, low protuberance on the dorsolateral margin of the snout measuring 25mm long, 15mm wide, and raising ~5mm from the surrounding snout. Neither the depression of the fossa nor the associated protuberance are sculptured, in contrast with the surrounding bone. The interior of the fossa is not smooth, but interior detail has been destroyed. In ventral aspect, the maxillae contact medially to form the majority of the secondary palate. 19 alveoli are preserved on the tooth row, with seven in-situ tooth crowns on the right and eight on the left. The suture with the palatines originates at the rostral apex of the posterior palatine vacuity and is broadly infolded, terminating medially at the choanae. The maxillae form the rostral margin of the choanae. Laterally, the maxilla contacts the jugal caudal to the posterior palatine vacuity and is overlain dorsally by the jugal. Nasal The margins of the nasals are subparallel between the maxillae, swelling laterally to a maximum width even with the rostral margin of the maxillary fossa. At the caudal margin, the nasal contacts the frontal and lies lateral to the frontal, wedging between the frontal and prefrontal. The dorsal surface is sculptured by indistinct rugosities and pits 2-4mm in diameter which obscure the caudal margins and sutures with the lacrimal, prefrontal, and frontal. The midline suture between the nasals is straight and forms a distinct groove along the sagittal plane of the snout. Rostrally, the nasals wedge medially between the caudal processes of the premaxillae and slightly overlap laterally the occipital-most point of the premaxillae by <8mm, resulting in a sharp W-shape. This differs from Goniopholis simus (Salisbury et al., 1999) and G. baryglyphaeus (Schwarz, 2002). This arrangement can be seen on OMNH 2322 and is more easily seen on that specimen.

18 7 Lacrimal in dorsal aspect, the lacrimal is subtriangular with the acute apex directed rostrally wedging between the maxilla and nasal. The medial contact with the nasal is complex with V-shaped rostrocaudally directed interfingerings. The lacrimals extend rostrally to even with the rostral margin of the maxillary fossa. The element reaches its widest point approximately 1/3 the distance from the caudal margin of the maxillary fossa and narrows caudally to the contact with the orbit. The lacrimal forms part of the rostral margin of the orbit. The dorsal surface is sculptured by fairly distinct shallow circular to subcircular pits ~3mm in size. The jugal is contacted laterally along a suture extending rostrally from the rostrolateral apex of the orbit. Prefrontal The prefrontal is narrow, 45mm long and 22mm wide. It is roughly triangular in shape, with the acute apex oriented rostrally between the maxilla and lacrimal. The caudal margin forms part of the rostral margin of the orbit. The dorsal surface is sculptured by indistinct shallow rugosities. The exact contact with the nasal is mostly obscured by sculpturing. Frontal In dorsal aspect, the frontals are spanned by a transverse interorbital crest. This crest forms a distinct step neatly separating the snout and skull table. Rostral of the crest, sculpturing is by indistinct rostrocaudal directed rugosities and caudal by distinct shallow circular pits to 5mm in size. Rostrolateral contact with the prefrontal is largely obscured by sculpturing. Laterally, the frontal forms part of the dorsomedial margin of the orbit and contacts the rostromedial process of the postorbital. The caudolateral margin forms the rostromedial margin of the supratemporal fenestra which is slightly raised. Caudally, the frontal narrows considerably medial to the supratemporal fenestra to contact with the parietal. The caudal process features a deep groove corresponding to the midline suture flanked by the raised medial margins of the supratemporal fenestrae. Dorsolaterally within the fenestra and in ventral aspect the frontal is unsculptured.

19 8 Postorbital In dorsal aspect, the rostrolateral process of the postorbital forms the dorsocaudal margin of the orbit and the rostral margin of the infratemporal fenestra. This process is small, smooth, and rounded and extends ventrolaterally to contact the postorbital process of the jugal. The rostromedial process separating the orbit from the supratemporal fenestra is sculptured on the dorsal surface by shallow distinct rounded pits to 5mm in diameter and contacts the frontals medially at the rostral apex of the supratemporal fenestra in an interfingered suture. The caudal process is contiguous with the rostromedial process and contacts the squamosal caudally, slightly inserting into the squamosal in an offset V-shape. The ventromedial margin is obscured by damage to the skull, but is presumed to contact the laterosphenoid medially. There is a distinct groove along the ventral surface of the rostromedial process. Parietal The parietal forms the caudomedial margin of the supratemporal fenestra, and this margin is slightly raised. The parietal contacts the caudal process of the frontal rostrally and the squamosal laterally. Sculpturing on the dorsal surface is consistent with surrounding elements. The occipital margin is rough and slightly concave with slight lateocaudal protuberances overhanging the posttemporal fenestrae. Squamosal The occipital margin of the squamosal is concave, as is contact with the parietal. The rostrally-directed postorbital process contacts the postorbital, broadly overlapping it laterally and slightly medially. The squamosal is roughly subtriangular in dorsal aspect and heavily sculptured as the rest of the skull table. The dorsal surface of the caudolateral process has a distinct, heavily sculptured, protuberance 40mm long and 20mm wide and elliptical in shape. A deep furrow separates it from the rest of the squamosal. Supraoccipital The supraoccipital is only visible in caudal aspect and appears as a ventrally-directed triangle inclined rostroventrally. It is bound forsally by the parietal and laterally by the otoccipital. It consists of a 5mm wide dorsoventrally directed medial ridge flanked laterally by deep 7mm wide depressions.

20 9 Otoccipital The otoccipital is visible primarily in caudal aspect and does not extend laterally past the lateral margin of the squamosal. The paraoccipital process forms a broad, ovoid plate directed caudolaterally, expanding laterally and inclined rostroventrally. The occipital surface is slightly concave. In ventral aspect, the otoccipital appears to lie adjacent to the quadrate at the lateral end, although a deep groove separates the ventral margin from the rest of the skull. Laterally, the paraoccipital process broadly contacts the squamosal dorsally. Basioccipital and Basisphenoid The occipital condyle is formed entirely by the basioccipital. In caudal aspect, the basioccipital is bounded dorsally by the otoccipitals and is oriented dorsoventrally. Ventral to the basioccipital, the basisphenoid expands laterally and features a median ridge flanked by shallow depressions. The caudolateral margin is extended to form a dorsoventrally directed flange. Rostral to this flange, the braincase is severly smashed in both OMNH 2392 and OMNH Exoccipital In ventral aspect, the exoccipital is exposed as a rectangular flange 45mm long, 25mm wide, and extending caudolaterally away from the basisphenoid. It contacts the quadrate rostrolaterally and the otoccipital caudally. The caudal margin forms a distinct ridge. Jugal The jugal is long and narrow, forming the ventrolateral margin of the infratemporal fenestra and orbit. It rostrally contacts the maxilla in a broad lap joint from just rostral of the postorbital bar to the maxillary fossa. Caudally, it contacts the quadratojugal in a lap joint at the caudal-most apex of the infratemporal fenestra. The postorbital process is narrow, originating on the ventromedial surface and bowed slightly medially and dorsally to contact the jugal process of the postorbital in a butt joint to form the postorbital bar. In dorsal aspect, the dorsal and lateral surfaces are sculptured by distinct shallow pits to 5mm across, identical to the sculpturing of the skull table. In ventral aspect, the jugal is not sculptured.

21 10 Quadratojugal In dorsal aspect, the quadratojugal is divided into two parts: a lateral rugose surface sculptured with distinct pits consistent with surrounding elements and a medial unsculptured surface. A rostrally-directed process penetrates the caudal margin of the infratemporal fenestra just ventral to contact with the squamosal. The quadratougal is overlain mediodorsally by the squamosal and contacts the jugal rostrally in a butt joint running mediolaterally originating from the caudal tip of the infratemporal fenestra. In ventral aspect, the quadratojugal is smooth and subrectangular in outline. Quadrate The quadrate is unsculptured and broad laterally. It is overlapped by the squamosal dorsomedially and the quadratojugal rostrolaterally. The caudomedial margin curves ventrally, becoming more sharply downturned caudally so that the medial process of the mandibular condyle is directed dorsolaterally at nearly 45 o. The ventral surface exhibits a midline ridge along the long axis. Palatine The rostral portion of the palatine is flat and triangular, with the rostrolateral portion inserting into the maxilla. The palatine contacts the maxilla rostrally from the rostral-most apex of the posterior palatine vacuity medially to the choanae. The caudal portion of the palatine becomes very narrow, forming a slender cylinder along the lateral margin. The caudal margin contacts the pterygoid. Pterygoid The pterygoids are not well preserved. A 20mm portion of the right element at the contact with the palatine is present. It is thicker medially, expanding into a broad plate facing rostrally and slightly medially and inclined caudolaterally. This plate lies lateral to the braincase. Discussion Comparison to other taxa Mook (1964) noted similarity of Amphicotylus stovalli to Goniiopholis felix and particularly A gilmorei in overall shape if not specific detail. The external naris of A. stovalli is wider than it is long, a characteristic shared with A. gilmorei and A. lucasii. Also, the premaxillas of these taxa are broad and deep while the distance anterior to the

22 11 premaxillary notch is relatively short (Mook, 1964). However, the naris of A. stovalli incorporates a rostrally-directed projection of the premaxilla on the caudal margin resulting in a constricted figure-eight naris unique to that taxon. The lacrimal of A. stovalli is also subtriangular in dorsal aspect, as opposed to the broader rostral region and more blunted termination observed in other goniopholidids. Common to all currently known Morrison Formation goniopholidids is a very distinct termination of the nasal passages. In all except G. Felix for which the palate is not known the choanae form a long, slender channel completely bisecting the palatines. This channel is bound rostrally by the maxilla and caudally by the pterygoid. It is bisected along its length by a narrow septum consisting of the vomer (Pritchard, 2011). In Eutretauranosuchus delfsi, A. lucasii, and A. gilmorei, the choanae is exceedingly long at >1/3 the total length of the skull and constricted by medial expansion of the palatines lending an hourglass shape. This constriction is as extreme in some specimens as to almost separate the channel in two. Indeed, YPM 517, the E. delfsi holotype, shows such extreme constriction the anterior portion of the choanae was initially incorrectly construed as a separate opening (Mook, 1967; Smith et al., 2010). This morphology is also observed in Calsoyasuchus valliceps of the Lower Jurassic Kayenta Formation (Tykoski et al., 2002). However, not all North American taxa show this condition as evidenced by an undescribed skull from the Cretaceous of Arkansas (TMM , pers. obs.; Langston, pers. com. 2007). It should be noted that though a rostrocaudally bisected choanae is not found in North American forms, the morphology is reported in other goniopholidids. Buffetaut and Ingavat (1980) report anterior expressions of the nasal passages in Sunosuchus maioi from the Upper Jurassic Hokou series of China. However, their reconstruction involves anterior openings of the choanae entirely contained within the maxilla and extensive contact of the palatines rostrally. This contrasts with the condition originally

23 12 reconstructed for Eutretauranosuchus where the anterior openings are bound caudally by the palatines and thus the palatines do not contact rostrally. The choanae of A. stovalli differ significantly from that of other Morrison Formation goniopholidids. Whereas in A. gilmorei, A. lucasii, and E. delfsi the choanae extend far into the pterygoid so that the caudal margin is well behind the orbits and very near the back of the skull, in A. stovalli it terminates approximately even to the rostral margin of the orbits and the pterygoids meet broadly caudal to this margin. As the caudal regions of both A. stovalli specimens are damaged and largely missing, an alternative morphology cannot be ruled out. It is possible the preserved choanae represents only the rostral portion and the palatines bisect the nasal passages in the manner similar to that originally reconstructed for Eutretauranosuchus by Mook (1967) and Sunosuchus maioi (Buffetaut & Ingavat, 1980), and the true choana is located farther caudal. However, this reconstruction does differ significantly in that in A. stovalli, the palatines are entirely separated and the constriction occurs farther caudal than in Eutretauranosuchus or S. maioi. In either scenario, this morphology is unique to A. stovalli, and is not observed in other crocodyliforms. Status of Morrison Formation goniopholidids North American goniopholidids have long been recognized as Goniopholis. However, the possibility these taxa are generically distinct from their European counterparts has been suggested (Clark, 1986; Salisbury et al., 1999; Lauprasert et al., 2007; Allen, 2007, 2010). Morrison Formation goniopholidids are united by their distinctive palate morphology, with the choanae entirely separating the palatines. By contrast, in European Goniopholis the choana lies between the palatine and pterygoid and the former element meets broadly anterior to the opening in a classic mesosuchian condition. Additionally, Morrison forms are united by a subtriangular prefrontal in dorsal aspect which extend rostrally farther than the lacrimal and excludes the lacrimal from contact with the maxilla, while in European forms the lacrimal extends farther rostrally

24 13 than the prefrontal and contacts the maxilla medially. The transverse intraorbital crest, though often present, is generally less pronounced in North American forms though this may be variable. Therefore, Goniopholis, under current understanding, should only refer to those European forms. North American Goniopholis can be considered a distinct taxonomic unit from European Goniopholis, and those taxa should be considered constituents of a single genus to which Amphicotylus Cope, 1878 would apply, of which Amphicotylus lucasii Cope, 1878 is type (Allen, 2010; 2011; contra Smith et al., 2010). It should be noted that though Diplosaurus Marsh, 1877 technically holds precedent, the incomplete nature of YPM 986, the only known specimen, prevents more precise attribution pending further discoveries. Whereas A. stovalli is unique among Amphicotylus species, A. lucasii and A. gilmorei are exceedingly similar as to be nearly indistinguishable in detail. Cursory investigation indicates that while the rostrum of A. lucasii grades smoothly into the infraorbital region, A. gilmorei shows a marked lateral expansion of the skull at the level of the orbits. However, a more in-depth analysis of CM 2312 the only known specimen of A. gilmorei reveals that this expansion is largely artificial due to breakage and lateral splaying of the jugal, particularly on the right side of the skull. It is thus likely that A. gilmorei can be considered a junior synonym of A. lucasii (Allen, 2010). This reduces the number of taxa known from the Morrison Formation to four: G. felix, E. delfsi, A. stovalli, and A. lucasii.

25 14 Table 1. Compilation of Morrison Formation goniopholidids Taxon Holotype Material Locality Referred Specimens Goniopholis felix (Marsh, 1877) YPM 986 dorsal skull roof Cañon City, CO Eutretauranosuchus delfsi Mook, 1967 CMNH 8028 skull Cañon City, CO BYU 17628; AMNH FR 570 Amphicotylus lucasii (Cope, 1878) AMNH 5766 postcrania Cañon City, CO AMNH 5782; AMNH 652 Amphicotylus gilmorei (Holland, 1905) CM 2312 skull Freezeout Mtns., WY Amphicotylus stovalli (Mook, 1964) OMNH 2392 skull Cimarron Co., OK OMNH 2322

26 Figure 1. Example of an extant crocodyliform. Alligator mississippiensis Photo by the author. 15

27 Figure 2. OMNH 2392 Amphicotylus stovalli, dorsal aspect photograph (top) and line interpretation (bottom). Known sutures and elements indicated on left side in red. Note the constricted figure-eight and lacrimal that is excluded from contact with the nasal. Position of maxillary fossa on lateral surface indicated by arrow. 16

28 Figure 3. OMNH 2392 Amphicotylus stovalli, ventral aspect photograph (top) and line interpretation (bottom). Palate elements indicated in red. Note the long, channel-like choana bound rostrally by the maxilla indicated by the arrow. 17

29 18 CHAPTER 2 NEW MATERIAL OF THE MANDIBLE OF DENAZINOSUCHUS KIRTLANDICUS Introduction The Upper Cretaceous Fruitland and Kirtland Formations in the San Juan Basin, New Mexico have yielded a diverse vertebrate assemblage including turtles, lizards, dinosaurs, and mammals (Lucas, 1981; Hunt & Lucas, 1992). Crocodyliforms from the San Juan Basin are less well known, with four species reported: the alligatoroids Leidyosuchus sp. and Brachychampsa montana based off of isolated postranial elements and a nearly-complete skull respectively, the large alligotoroid Deinosuchus, and the enigmatic but more common Denazinosuchus kirtlandicus (Gilmore, 1916; Reeside, 1924; Powell, 1972; 1973; Kues et al., 1977; Wolberg & LeMone, 1980; Lucas, 1992; Sullivan & Lucas, 2003; Lucas et al., 2006). Wiman (1932) originally described D. kirtlandicus as a new species of Goniopholis Owen, 1841 based on its general morphology, including overall skull shape, dermal sculpturing, lacrimal separating the maxilla from the prefrontal, presence of a skull table, and rectangular paravertebral osteoderms with an anterior-directed articulating spine. Despite these being largely plesiomorphic characteristics common in crocodyliforms, subsequent workers found little reason to question this assignment (e.g. Wolberg, 1980; Mateer, 1980; Buffetaut, 1982; Lucas, 1992). Lucas and Sullivan (2003) reassessed the holotype skull and erected it as a new genus distinguished primarily by the lack of a definite maxillary fossa on the lateral surface of the snout and enlarged supratemporal fenestrae. However, Lucas and Sullivan (2003) did note considerable similarity to goniopholidids, in particular Amphicotylus lucasii, and as such concluded that Denazinosuchus is closely related to Goniopholis. Although Denazinosuchus is the most common and distinctive crocodyliform in the San Juan Basin (Lucas et al., 2006), material is highly fragmentary. In 2001, elements

30 19 of a partial but articulated left mandible (NMMNH P-33828) were recovered in association with some fragmentary cranial elements within the Late Cretaceous (Campanian) De-Na-Zin Member of the Kirtland Formation. A nearly complete splenial is present in articulation with a nearly complete angular and in association with a fragmentary surangular, palatine, and nasal. The new material described here provides new insights into the morphology of Denazinosuchus and allows for further investigation of its placement among crocodyliformes. Abbreviations AMNH, American Museum of Natural History, New York, New York; NMMNH, New Mexico Museum of Natural History and Science, Albuquerque, New Mexico; PMU.R, Paleontological Museum, University of Uppsala, Uppsala, Sweeden. Systematic Paleontology CROCODYLIFORMES Hay, 1930 MESOEUCROCODYLIA Whetstone and Whybrow, 1983 DENAZINOSUCHUS Lucas and Sullivan, 2003 DENAZINOSUCHUS KIRTLANDICUS (Wiman, 1932) (Figs. 4-5) Holotype PMU.R 232; partial articulated skull (Fig. 1). Horizon and Locality Late Cretaceous (Campanian), De-Na-Zin Member, Kirtland Formation, San Juan County, New Mexico (Wolberg, 1980; Hunt et al., 1992). Referred Material NMMNH P-33828; articulated partial left mandibular ramus and associated partial right nasal and palatine. Horizon and Locality Late Cretaceous (Campanian), De-Na-Zin Member, Kirtland Formation, Locality L-4714, South Mesa, San Juan County, New Mexico. Revised Diagnosis A mesoeucrocodylian crocodyliform distinguished by supratemporal fenestrae that are much larger than the orbits, extensive participation by the splenial in a short mandibular symphasis, a ventral expansion of the splenial at the

31 20 symphasis, a rectangular caudal process of the palatine ventrally overlying the pterygoid, and a small neurovascular groove on the lateral surface of the maxilla. Description of Materail Observations from the holotype Reinvestigation of NMMNH C-2438, a high-quality cast of the holotype skull, broadly conforms to the reconstruction of Lucas and Sullivan (2003). An isolated element interpreted by Lucas and Sullivan (2003) as a fragmentary parietal and articulated fragment of squamosal bears special mention, however. Examination of this element reveals that the lateral curvatures identified as the mediocaudal margins of the supratemporal fenestrae are of drastically different curvature, with the left side being of considerably smaller radius resulting in asymmetry unexpected in a midline element and necessitating reconstructed supratemporal fenestrae of radically different size. Furthermore, the anterior surface of the reconstructed squamosal fragment is confluent with the lateral margin of the parietal and shows no sign of breakage as implied by Lucas and Sullivan (2003) to account for the difference in curvature. Therefore, we reject the interpretation of this element as a parietal with attached squamosal fragment and reaffirm Wiman s (1932) original interpretation of the fragment as the posterior corner of the right squamosal with a small fragment of the posterior process of the postorbital. The lateral surface of the snout shows a series of small neurovascular pits arranged linearly above the toothrow. Whereas the maxillary depression found in Goniopholis and related taxa (Buffetaut, 1982) is indeed not present (Lucas & Sullivan, 2003), at the same position along the snout, the neurovascular foramina are confluent forming a short, slit-like groove. Description of new material New material accessioned under NMMNH P consists of a partial left mandibular ramus in two portions, anterior and posterior with associated cranial elements. Quality of preservation is very good with no appreciable distortion or crushing.

32 21 This material represents the first known mandible from Denazinosuchus and expands on the known palate. Nasal A partial right nasal is preserved consisting of the caudal portion at the widest point of the element with the anterior process and caudal-most process broken away. The mediocaudal margin shows the suture with the frontal consisting of a series of longitudinal rugosities and overlain slightly by the frontal. The lateral margin exposes a tongue-and-groove articulation with the maxilla with a long, rectangular longitudinal ridge approximately half the thickness of the nasal running the length of the preserved suture. The dorsal surface of the nasal is sculptured while the ventral surface is smooth and concave longitudinally. Palatine The partial right palatine preserves the posterior end and is broken rostrally and caudomedially. The dorsal surface is very rugose while the ventral surface is smooth and has a shallow, broad longitudinal depression just lateral to the medial suture with the left palatine. Caudally, the palatine abuts and passes beneath the pterygoids. The posterior process at the contact is very broad and blunt, lending a near rectangular profile to the contact. The rostrolateral margin shows abutment with the very posterior-most projection of the maxilla, which terminates less than 1/5 the length along the preserved lateral margin. The remaining caudal half of the margin is smooth, delineating the medial boundary of the palatine vacuity. This participation of the palatine in the medial margin of the palatine vacuity differs from previous reconstructions of the palate (Wiman, 1932; Lucas & Sullivan, 2003), and also notes the first direct observation of the palatine in this taxon. The medial and caudal margin do not appear to preserve the margins of the choanae, but the mediocaudal portion of the element is severely broken. As such, the position of the choanae cannot be confidently reconstructed at this time. Angular The angular is long and dorsoventrally very broad, rounded anteroventrally, and flattened caudoventrally. The dorsal margin of the medial surface is smooth outlining the vental margin of an extensive interior mandibular fenestra.

33 22 Extending caudally, the medial surface almost inverts to face ventrolaterally as it approaches the articular. The caudal margin is broken off just rostral to contact with the articular. The lateral surface is heavily sculptured with shallow circular pits in the same manner as the cranium of the holotype. Ventral and medial surfaces are smooth. The angular overlaps the splenial laterally and ventrally and the coronoid laterally, though the latter element is not preserved. The dorsal margin is badly broken, obliterating contact with the surangular. The rostral ~1/3 of the preserved length of the rostrodorsal margin is largely intact and is smooth both dorsally and laterally forming a smooth lamina where the element was overlain laterally by the dentary. A damaged apparently smooth margin immediately caudal to this contact may represent the ventral margin of an external mandibular fenestra or may show contact with the surangular. If indeed indicative of an external mandibular fenestra, its size and extent cannot be determined with current material. Splenial The splenial is preserved in two pieces, rostral and caudal. The caudal fragment is in articulation with the angular which overlays it laterally while the rostral fragment is in isolation. The splenial is long and slender and sinusoidal in dorsal aspect. The caudal process is narrow and rectangular in cross-section while the rostral fragment widens considerably along its length. The lateral surface is smooth while the dorsal surface preserves a worn groove along the length immediately ventral to the expected position of the toothrow, though no distinct alveoli can be determined. The rostral-most tip is absent, but the rostral end does expand dramatically ventrally at the level of the symphasis. The splenial participates extensively in the mandibular symphasis. The anteromedial surface preserves a radial series of rugosities forming an articular surface ~45mm long as preserved. Surangular An isolated fragment identified as a partial right surangular was found in association with the mandible. The fragment is small, but shows a near

34 23 rectangular cross-section and a very narrow (~40mm) dorsoventral height. The ventral margin shows a rugose contact surface. Discussion NMMNH P is tentatively referred to Denazinosuchus kirtlandicus pending further discoveries based on general form and suture pattern, expected size, bone sculpturing, and the overlap of associated elements with the holotype, specifically the nasal. Comparison to the same element of the holotype implies a reconstructed skull size for NMMNH P comparable to that of the holotype PMU.R 232. Denazinosuchus has long been associated with Goniopholididae (Wiman, 1932; Kälin, 1955; Wolberg, 1980; Mateer, 1980; Buffetaut, 1982; Lucas, 1992; Williamson, 2000; Lucas & Sullivan, 2003). In general form and antorbital suture pattern it does indeed resemble Amphicotylus and Goniopholis. However, it lacks the distinctive maxillary fossa on the lateral margin of the snout characteristic of goniopholidids. It also lacks an interorbital transverse crest on the frontal as observed in Goniopholis (Salisbury et al. 1999; De Andrade & Hornung, 2011) and to a lesser extent in Amphicotylus stovalli (Allen, 2007), and A. lucasii (pers. obs.). Indeed, those characteristics used to unite Denazinosuchus with Goniopholis are not unique to that clade and those characteristics by which it differs are largely congruent a basal mesoeucrocodylian from the Cenomanian Woodbine Formation of Texas (Allen et al., 2011), herein termed the Arlington Form. Both taxa share, in addition to general form, goniopholidid-style paravertebral osteoderms with a pitted dorsal surface and anteriorly-directed articular spine; enlarged supratemporal fenestrae which are larger than the orbits; nasals which do not contact the external naris; a T-shaped frontal; blunt, nearly rectangular caudal process of the palatine overlapping ventrally the pterygoid; and extensive participation by the splenial in a short mandibular symphasis. However, Denazinosuchus possesses a broader distal end to the splenial and lacks the enlarged paired pseudocanines found in the Arlington Form.

35 24 The potential lack of an external mandibular fenestra is of interest. Absence of this opening has been considered characteristic of goniopholidids (Clark, 1994; Foster, 2006), and indeed is absent in Anetophthalmosuchus (Salisbury & Naish, 2011) and Amphicotylus stovalli (pers. obs.). However, external mandibular fenestrae have been reported in other goniopholidid taxa including Goniopholis simus (Salisbury et al., 1999; Salisbury, 2002), Eutretauranosuchus delfsi (Foster, 2006; Smith et al. 2010), and?amphicotylus lucasii ( AMNH DVP 652, pers. obs.). As such, the presence or absence of this opening cannot be considered characteristic of Goniopholididae. Reinvestigation of Denazinosuchus in light of this new material and a more recent understanding of crocodyliform phylogeny forces a reassessment of its classification. Denazinosuchus is not a Cretaceous North American goniopholidid as has been long assumed, but instead represents a more plesiomorphic and ambiguous position amongst neosuchians.

36 Figure 4. PMU.R 232 Denazinosuchus kirtlandicus holotype. Skull in dorsal aspect with line reconstruction. Plate IV of Wiman (1932). 25

37 26 Rostral Figure 5.New material referred to Denazinosuchus kirtlandicus. (A) partial right nasal, dorsal aspect. (B) partial right palatine, ventral aspect. (C) partial surangular, lateral aspect; (D) partial left mandible; splenial and articulated angular, lateral aspect.

38 27 CHAPTER 3 PHYLOGENETIC ANALYSIS OF GONIOPHOLIDIDAE Introduction Crocodyliform systematics has been highly influenced by the work of Benton and Clark (1988) and especially Clark (1994) whose character set has formed the basis of nearly every other crocodyliform study (e.g. Wu et al., 1994a; Wu et al., 1994b; Gomani, 1997; Wu et al., 1997; 2001; Buckley & Brochu, 1999; Buckley et al., 2000; Clark et al., 2000; Larsson & Gado, 2000; Pol et al., 2001; Sereno et al., 2001; Brochu et al., 2002; Clark & Sues, 2002; Ji et al., 2002; Pol, 2002; 2003; Tykoski et al., 2002; Rogers, 2003; Pol et al; 2004; Pol & Norell, 2004a; b; Turner & Calvo, 2005; Gasparini et al., 2006; Turner et al., 2005; Turner & Buckley, 2008; Smith et al., 2010; but see Ortega et al., 2000). However, understanding of the interrelationships within Crocodyliformes is in a constant state of flux. Phylogeny reconstruction in Crocodyliformes is highly dependent on taxon sampling, especially of basal mesoeucrocodylians and neosuchians (Turner & Buckley, 2008). Goniopholididae was established as a family by Cope (1875). Steel (1973) included the family in Mesosuchia and ascribed the genera Baharijodon, Coelosuchus, Dakotasuchus, Doratodon, Eutretauranosuchus, Goniopholis, Itasuchus, Microsuchus, Oweniaschus, Pertosuchus, Pinacosuchus, Pliogonodon, Polydectes, Shamosaurus, and Symptosuchus to it. It has subsequently been relegated to a wastebasket taxon status, though recent work has served to clarify certain taxonomy, particularly among European forms (e.g. Salisbury et al., 1999; Salisbury, 2002; Schwarz, 2002). Goniopholidid fossils are distributed throughout Western Europe, North America, and eastern Asia a distinctly Laurasian distribution. Historically, some material has been identified from Gondwannan localities, but this material is either non-diagnostic or subsequent work has proposed a different relationship than Goniopholididae (e.g. Buffetaut, 1985; 1988; Carvalho et al., 2004).

39 28 Sereno (2005) suggested a branch-based definition for the group coinciding with the system established for TaxonSearch (Sereno et al., 2005) of the most inclusive clade containing Goniopholis crassidens Owen, 1841, but not Pholidosaurus geoffroyi (Owen, 1884), Alligarotellus beaumonti Gervais, 1871, Peirosaurus torminni Price, 1955, Araripesuchus gomesii Price, 1959, Notosuchus terrestris Woodward, 1896, or Crocodylus niloticus (Laurenti, 1768). Though technically in general use, this definition has not been formally put forward outside of TaxonSearch. For the purposes of this analysis, I affirm Sereno s (2005) definition as a working phylogenetic definition of Goniopholididae with the modification of Goniopholis simus Owen, 1878 as the internal specifier. The reason for this change is threefold: 1) Goniopholis crassidens is known almost exclusively from postcrania making it unsuitable for inclusion in a data matrix consisting predominately of cranial characters, 2) material of Goniopholis simus is comparatively more abundant making it one of the most wellrepresented goniopholidid taxa, and 3) Goniopholis simus may be a junior synonym of G. crassidens (Salisbury et al., 1999; Salisbury, 2002; Salisbury & Naish, 2011). Status of goniopholidid phylogenetics Goniopholididae has appeared in several phylogenetic analyses, though typically as only a single exemplar taxon. Though Goniopholididae has been subjected to phylogenetic analysis in recent years (e.g. Buckley et al., 2000; Tykoski et al., 2002), these have been limited in scope. As such, no coordinated attempt to revise its taxonomy has been made, and attempts have focused primarily on Europe and have not been phylogenetic in nature (e.g. Salisbury et al., 1999). In most previous work, Goniopholididae includes Goniopholis, Eutretauranosuchus, Sunosuchus, and Calsoyasuchus, though mostly not by phylogenetic testing (Mook, 1967; Wu et al., 1996; Salisbury et al. 1999; Schwarz, 2002; Tykoski et al., 2002). In the majority of phylogenetic analyses to include goniopholidids, they are resolved as sister to Bernissartia + Eusuchia to the exclusion of pholidosaurs,

40 29 thalattosuchians, and dyrosaurs (e.g. Tykoski et al, 2002; Smith et al., 2010). Though less common in the literature, alternate topologies have been proposed (Fig. 6) for Goniopholididae more closely related to pholidosaurs and thalattosuchians than Eusuchia (e.g. Sereno et al., 2001; Jouve et al., 2006). One analysis, Jouve et al. (2006), recovered Goniopholididae as paraphyletic with Eutretauranosuchus, Sunosuchus, and Calsoyasuchus forming a clade and Vectisuchus and Goniopholis as successive sister taxa to Pholidosauridae + Thalattosuchia. This topology was not well supported and was dependent on the inclusion of Vectisuchus. Jouve et al. (2006) concluded this result may be due to the effect of convergence in long, tube-snouted ( longirostrine ) anatomy in Vectisuchus, dyrosaurs, and thalattosuchians. Phylogenetic Analysis The comprehensive description of G. stovalli as well as new observations of other Morrison Formation goniopholidids (Smith et al., 2010; Pritchard, 2011) and the description of new specimens from Europe (Salisbury & Naish, 2011) allow for testing of the phylogenetic relationships of Goniopholididae. As Denazinosuchus and Vectisuchus have often been attributed to the goniopholidids (Wiman, 1932; Buffetaut & Hutt, 1980; Mateer, 1980; Wolberg, 1980; Buffetaut, 1982; Lucas, 1992; Lucas & Sullivan, 2003; Jouve et al., 2006; Salisbury & Naish, 2011), this also provides an opportunity to test the phylogenetic relationships of those taxa. Taxon sampling and dataset This analysis is based on modification of previous datasets (Clark, 1994; Wu & Sues, 1996; Pol, 1999; Ortega et al., 2000; Pol & Norell, 2004a; Gasparini et al., 2006; Turner et al., 2005; Allen, 2007; 2010), and particularly that of Turner and Buckley (2008). Modifications include character definitions and scorings. One new character was added to further account for variation among goniopholidids describing the morphology of the infraorbital crest. Due to the potential affinity of Goniopholididae with Pholidosauridae and Thalattosuchia, taxon sampling was increased for these clades.

41 30 Goniopholidid taxa were selected based on the presence of good quality, diagnostic cranial material. Putative taxa not possessing these (e.g. Goniopholis hartti, known only from teeth) were not considered. This includes a full sampling of all currently recognized goniopholidids of the Morrison Formation, Calsoyasuchus valliceps from the Lower Jurassic Kayenta Formation, two Asian, and four European goniopholidids. This is the largest and most inclusive sampling of goniopholidids to date. The total dataset is based on 64 taxa and 216 characters. Taxa were coded from the literature with the exception of the Morrison Formation goniopholidids excluding Eutretauranosuchus, G. simus, Denazinosuchus, and an undescribed specimen from the Cretaceous Woodbine Formation of Texas the Arlington Form which were coded from direct observation. Vectisuchus was included and recoded to test the affinity of Goniopholididae and Pholidosauridae following Jouve et al. (2006). Previously, only two European taxa, Goniopholis simus and G. baryglyphaeus, have been considered phylogenetically. Recently, two new taxa, Goniopholis willetti and Anetophthalmosuchus hooleyi, have been described from the Lower Cretaceous Wealden Supergroup of southern England (Salisbury & Naish, 2011). Though they avoid statements of relationships, Salisbury and Naish (2011) noted considerably similarity with G. simus, G. baryglyphaeus, and G. gracilidens. Remains of these two taxa include well-preserved and mostly complete cranial material allowing them to be incorporated into a phylogenetic matrix for the first time. Results General results and North American goniopholidids The dataset was analyzed using TNT v. 1.1 (Goloboff et al., 2003). A heuristic tree search strategy was implemented using random addition sequences followed by Tree Bisection and Reconnection (TBR) branch swapping holding 10 trees per replicate. Character states were unordered. Zero-length branches were collapsed if they lack support in any most parsimonious reconstruction (i.e. Rule 1 of Coddington & Scharff,

42 ). Nodal support is expressed by decay indices (Bremer, 1994) and statistical support calculated by jackknife resampling (Farris et al., 1996). This results in 280 most parsimonious trees (MPTs) of length 782 (CI = 0.355, RI = 0.681). All most parsimonious trees (MPTs) recovered in this analysis (Fig. 7) resolve an overall topology broadly consistent with previous analyses, though it does differ in the placement of Atoposauridae basal to Eusuchia + Pholidosauridae + Thalattosuchia as opposed to sister to Eusuchia + Goniopholididae (e.g. Turner, 2004; Turner & Buckley, 2008). Goniopholididae is monophyletic and sister to Bernissartia + Eusuchia and consists of Goniopholis, Sunosuchus, Siamosuchus, Anetophthalmosuchus, Eutretauranosuchus, and Amphicotylus as well as G. felix. North American forms resolve as monophyletic to the exclusion of all other goniopholidids. The North American clade is defined by their distinctive palate morphology with a long, channel-like choanae entirely separating the palatines (character 29.1) and the Morrison Formation clade further by triangular prefrontals which extend rostrally beyond the lacrimals and completely exclude the lacrimals from contact with the nasals (characters 6.1; 7.2). Within the North American group, the Lower Jurassic Calsoyasuchus is the basal-most member. Unfortunately, outside of this North American clade, goniopholidids resolve as a basal polytomy. Investigation reveals this is almost exclusively due to the influence of Goniopholis willetti. The derived long, narrow rostrum of this taxon renders it highly labile, falling everywhere from the basal-most member of the group to sister to the North American clade. Removal results in 39 most parsimonious trees of length 777 (CI = 0.358, RI = 0.684) and increased precision among non-north American goniopholidids. Under these conditions (Fig. 8a), the Lower Cretaceous Anetophthalmosuchus is resolved as sister taxon to the Upper Jurassic Goniopholis baryglyphaeus with which it shares extensive and homogenous sculpturing of rostral dermal elements (Salisbury & Naish, 2011). Additionally, the two Asian taxa, Sunosuchus junggarensis and

43 32 Siamosuchus, resolve as sister taxa despite the latter s incompleteness based predominantly on their reduced infraorbital crest morphology restricted to the frontals. Finally, Goniopholis simus is sister taxon to all other goniopholidids. Alternatively, ambiguity in non-north American goniopholidids is a result of the highly homoplastic nature of the infraorbital crest. Exclusion of this character (character 216) results in 220 trees of length 780 (CI = 0.355, RI = 0.681). Goniopholis willetti is still labile in this analysis, but is more restricted, falling either basal to all other goniopholidids, sister to G. simus, or sister to the North American clade, or sister to a Siamosuchus + Sunosuchus + Anetophthalmosuchus + G. baryglyphaeus clade (Fig. 8b). Denazinosuchus and Vectisuchus The Upper Cretaceous North American taxon Denazinosuchus kirtlandicus does not resolve as a goniopholidid. It is found as sister taxon to the undescribed Arlington Form in a small, weakly supported clade with the enigmatic Vectisuchus united by the shape of the postorbital (character 24.1) and slight evagination around the orbits (character 188.1). This group is sister to Pholidosauria + Thalattosuchia, and this relationship is supported by a flattened postorbital bar (character 21.0), elongated retroarticular process (character 55.3), and extensive involvement of the splenial in the mandibular symphasis (character 61.2). The position of Denazinosuchus basal to pholidosaurs is dependent on the inclusion of the Arlington Form. Removal of this taxon results in Denazinosuchus placed within Pholidosauridae, alternatively sister to Oceanosuchus or Oceanosuchus + Terminonaris (Fig. 9). Topology aside from this change is unaffected. Consistent with the relationship found by Jouve et al. (2006), Vectisuchus falls outside of Pholidosauria + Thalattosuchia. Exclusion of Denazinosuchus or the Arlington Form does not affect this result. However, if the Arlington Form and Denazinosuchus are both removed from the analysis, Vectisuchus and Pholidosaurus collapse to a polytomy at the base of Pholidosauridae + Thalattosuchia.

44 33 Discussion North American goniopholidids North American Goniopholis cannot be ascribed to Goniopholis sensu stricto. This phylogenetic analysis corroborates anatomical observation that Goniopholis should only refer to European forms and North American forms should be ascribed to Amphicotylus Cope, The missing palate of G. felix renders it labile within the Morrison Formation clade, so the status of Diplosaurus Marsh, 1877 cannot be determined at this time. In this dataset, Amphicotylus lucasii and A. gilmorei are almost identical in coding, differing only where a character is obscured in one or the other due to non-preservation (e.g., A. gilmorei does not preserve a lower jaw or postcrania). As expected, these two are resolved as sister taxa, lending further support to the conclusion A. gilmorei is a junior synonym of A. lucasii. The monophyly of Morrison Formation goniopholidids is of interest. Amphicotylus and Eutretauranosuchus could represent an endemic radiation of goniopholidids in the American West. The persistence of the incomplete palate, shared with Calsoyasuchus, while contemporary taxa elsewhere (e.g. G. baryglyphaeus) posess a more complete palate may represent geographic isolation of these taxa during the Jurassic. Though the incomplete palate can be considered derived in this dataset, it is possible this condition should represent the basal condition in goniopholididae, as it is present in the basal-most member. New data and new discoveries, particularly of basal Early Jurassic goniopholidids, are anxiously awaited. Denazinosuchus This analysis reveals a somewhat ambiguous taxonomic relationship for Denazinosuchus. However it cannot be considered a constituent of Goniopholididae. Instead, it is more closely associated with Phlidosauridae, though how closely depends on the inclusion of the Arlington Form. Current material referred to the Arlington Form is fragmentary, but the similarity between these two taxa is striking. It is interesting to note that, though aligned with longirostirine taxa, neither of these two forms deviate strongly from a classic strongly triangular rostrum. Furthermore, it is

45 34 possible Denazinosuchus, and the Arlington Form represent the vanguard of a heretofore unidentified clade of neosuchians basal to pholidosaurs and thalattosuchians. This new clade would likely be distinguished by enlarged supratemporal fenestra on a broad skull table and extensive involvement of the splenial in the mandibular symphasis regardless of symphasis length. New discoveries and a more thorough sampling of basal neosuchians may help illuminate these issues. A potentially lucrative avenue of investigation would be crocodyliforms from the Cretaceous of Texas, for example Woodbinesuchus from the Woodbine Formation (Lee, 1997). Vectisuchus The weakly tubular-snouted Vectisuchus is not a goniopholidid under this analysis, as is corroborated by the apparent lack of a maxillary fossa. Contrary to the results of Jouve et al. (2006), the inclusion of Vectisuchus in this analysis does not affect Goniopholididae resolving as closer to Pholidosauridae + Thalattosuchia than Bernissartia + Eusuchia. In fact, that topology is recovered only in a minority of MPTs with no unambiguous support only if Vectisuchus is excluded from the analysis but Denazinosuchus and the Arlington Form are retained. In all results, Goniopholididae is monophyletic, and in no result is Vectisuchus in any other topology than basal to Dyrosauridae + Thalattosuchia. Jouve et al. (2006) suggest Vectisuchus s affinity with the pholidosaurs, dyrosaurs, and thalattosuchians is due to convergent evolution of a long, tubular rostrum in these taxa. However, Denazinosuchus and the Arlington Form, with which Vectisuchus is closely related in this analysis, are by no means longirostrine, and in the absence of the Arlington Form, Denazinosuchus falls out with Sarcosuchus and Oceanosuchus, two pholidosaurs notable for possessing a less tubular rostrum. This implies that certain characters assumed to be related to longirostry (e.g. extensive splenial involvement in the symphasis) may not be entirely correlated with rostrum morphology. Biostratigraphy Calibrating the recovered phylogeny with stratigraphy reveals substantial unreported diversity in neosuchians (Fig. 10). The position of Calsoyasuchus as the

46 35 basal-most member of North American goniopholidids necessitates a ghost lineage for Amphicotylus + Eutretauranosuchus extending to the Early Jurassic. The earliest-reported goniopholidid from Europe is G. baryglyphaeus from the Upper Jurassic (Kimmeridgian) of Portugal (Schwarz, 2002), approximately contemporaneous with the Morrison Formation (Kowallis et al., 1998; Mateus, 2006). As Calsoyasuchus is nested within Goniopholididae, this necessitates the invocation of ghost lineages for European and Asian forms to the Early Jurassic as well. Furthermore, the potential topology of Goniopholis simus as sister taxon to all other goniopholidids indicates substantial missing diversity for that lineage. The position of Vectisuchus and Denazinosuchus as sister to the Pholidosauridae + Thalattosuchidae clade requires an extensive ghost lineage to the Early Jurassic, representing much unrepresented diversity in that lineage. The alternate topology for Denazinosuchus as nested within Pholidosauridae as recovered by exclusion of the Arlington Form from the dataset is potentially more stratigraphically congruent for that taxon, but as the Cretaceous Vectisuchus remains outside the clade, this does not alleviate. If Vectisuchus, Denazinosuchus, and the Arlington Form represent a previously unidentified major division of neosuchian phylogeny, attention should be focused on Early Cretaceous formations of North America and Europe. Further investigation and discoveries are required to resolve these taxonomic issues. Conclusions Goniopholidid systematic taxonomy is far from resolved. The most inclusive phylogenetic dataset of goniopholidids to date reveals a nested North American clade characterized by a distinctive channel-like choana morphology. However, relationships among Goniopholididae as a whole, and particularly European and Asian taxa, remain ambiguous. North American goniopholidids of the Jurassic are well represented. By contrast, goniopholidids from the Cretaceous of North America are notably underrepresented, with identified taxa either being found not to be goniopholidid at all (e.g.

47 36 Denazinosuchus kirtlandicus) or currently undescribed. Future work will necessarily focus on taxon sampling, particularly of basal neosuchians, to further elucidate taxonomy.

48 37 A B C Figure 6. Summary of phylogenetic placements of Goniopholididae. (A) monophyletic, closer to Eusuchia (modified from Tykoski et al., 2002) (B) monophyletic, closer to pholidosaurs (modified from Sereno et al., 2001) (C) paraphyletic, closer to pholidosaurs (modified from Jouve et al., 2006)

49 Figure 7. Phylogenetic results of entire dataset.strict consensus of 280 most parsimonious trees of length 782 (CI = 0.355, RI = 0.681). Nodal support indicated by Jackknife (>50) and Bremer (>1) values. Character state changes at lettered nodes are tabulated in Appendix C. 38