Marshall University Marshall Digital Scholar Biological Sciences Faculty Research Biological Sciences 7-2003 Preliminary Report on the Osteology and Relationships of a New Aberrant Cryptocleidoid Plesiosaur from the Sundance Formation, Wyoming F. Robin O’Keefe Marshall University, [email protected] William Wahl Jr. Follow this and additional works at: http://mds.marshall.edu/bio_sciences_faculty Part of the Animal Sciences Commons, and the Ecology and Evolutionary Biology Commons Recommended Citation O’Keefe, F. R. & Wahl, W. (2003). Preliminary report on the osteology and relationships of a new aberrant cryptocleidoid plesiosaur from the Sundance Formation, Wyoming. Paludicola 4, 48–68. This Article is brought to you for free and open access by the Biological Sciences at Marshall Digital Scholar. It has been accepted for inclusion in Biological Sciences Faculty Research by an authorized administrator of Marshall Digital Scholar. For more information, please contact [email protected], [email protected]. Paludicola4(2):4&.68 July 2003 C bythe Roche$terInstitute of VertebratePaleontology PRELIMINARY REPORT ON THE OSTEOLOGY AND RELATIONSHIPS OF A NEW ABERRANT CRYPTOCLEIDOID PLESIOSAUR FROM THE SUNDANCE FORMATION, WYOMING F. Robin O'Keefe1 and William Wahl, JR.l 1-Department of Anatomy, New York College of Osteopathic Medicine, Old Westbury, New York 11568 <[email protected]> 2- Wyoming Dinosaur Center, J lO Carter Ranch Road, Thermopolis, WY 82443 <[email protected]> ABSTRACT The cryptocleidoid plesiosaur Taktwcfltslaram.eruiS, new genus, is described from the RedwaterShale:Memberof the Sundancefonnation. County, Narrona Wyommg.. Thebolotypcof thisspecies was a thatpllrtial skeleton since bas been lost. A neotypc:is designatedthat preserves $lime the elementspresent in the bolotype. A seooodspecimen is referred tothe taxon, IOd tlus specimen includes amialmaterial.TheprtSen�edcnarial elementsan: the left squm10581, a partial right ftonal. several isolated teeth, tbe parasphenoid,IDdlargeJ)OftlOnSof the left lind right ptcrygoids. Tbe skull sbaramany traits Wlththator Kllfurtero!/ltlUI'V.J, a cryptocleidoid plesiosaurfrom the KimmcridJC Clay of England. However, the palale is derived, and resembles those of the pooriy-undustood cimolia.uurid pie!>i()SIIlm of the Cretacc:Qus of the southern bcmisphen:. This similerity is established via cornperiJOnthe with skull of an undescribed taxoo fromlate Jurassic of Cuba. Thecryptocleidoid plesiosaurs underwent an extensive radiation in the Late Jurassic, and ll"IOfe research attention is needed, beginning with additionalprcpantion and collection of Ta�twctu INTRODUCTION 'Piesiosaurus shirleyensis' (now lost) did preserve teeth and a fragment of mandible possibly from this taxon Upper Jurassic plesiosaur materiaJ has been (Knight 1900). known from the (Oxfordian) Redwater Shale member This paper offers a preliminary description of of the Sundance Formation of Wyoming since the end a second cryptocleidoid taxon from the Redwater of the 19th century, being first mentioned by Marsh in Shale. Thecase will be madethat this taxonis the same 1891, and later elaborated by Marsh (1893, 1895) and as the taxon 'Tricleidus?' laramiensis erected by Mehl by Knight (1898, 1900). Mehl (1912) advanced the (1912), itself a revision of the taxon 'Cimoliosaurus' hypotheses that two small plesiosaur taxa occurred in /aramiensis Knight 1900. However, the taxonomy of the Redwater SbaJe, and that both showed affinities to this species is quite complex, and the difficulties are the cryptocleidoids (sensu O'Keefe 200I) of the compounded by the fact that Knight's holotype cannot (Callovian) Oxford Clay of England. The Sundance be located today. The tack taken here is to erect a Formation plesiosaurs received no further attention neotype of this species based on Knight's original until the 1990s,when field crews of the Tate Museum (valid) description, assign a new genus name as the in Casper, Wyoming began collecting new plesiosaur species is currently without a valid one, and then refer material from Natrona county. The taxonomic history other material to the taxon. The taxonomic issues of Sundance plesiosaurs, and the status of Pantosaurus involvedare discussedat length below. striatus, are reviewed in the preceeding paper by O'Keefe and Wahl (2003). Pantosaurus seems to have Cryptocleidoid Phylogeny and Relevance-A� had the longer neck of the two taxa present in the will be shown below, the cranial anatomy of this Redwater Shale. This taxon possesses at least 35 second RedwaterShale taxon is quite derived and very cervical vertebrae that are long antero-posteriorly, and important, because it sheds light on the anatomy and that are very simHar to those of the long-necked taxon relationships of the group of animals defined as the Muraenosaurus. No cranial material is currently known Cimoliasauridae by O'Keefe (200I). This group of from Pantosaurus, although Knight's specimen of bizarre animals is best known from the Cretaceous taxa 48 O'KEEFE AND WAHL-ABERRANT CRYPTOCLEIDOID PLESIOSAUR 49 Kiliwhekea and Aristonectes, but also includes the Etymoloc-Tate, in honor of Marion and Inez Jurassic taxon KimmerosauniS (O'Keefe 200I). A Tate, founders of the Tate Museum in Casper, cladistic analysis perfonned below shows that the Wyoming in 1980. -Nectes,Greek, meaning diver. second Redwater Sbale taxon is yet another member of this group. Sorting out the relationships of the Tatenectes laramiensisKnight 1900, new combination Cimoliasawidae has assumed new importance with the (Figures 1,2,3,4,5). recent publication of a paper contending that Aristonectes (and material referred to it) is an Holotype-W. C. Knight, uncatalogued. elasmosaur (Gasparini et al. 2003). It is our view that Disarticulated axial skeleton and nearly complete this assignment is incorrect; this view is supported by forelimb. This specimen is lost, but was figured and much character evidence in the cladistic analysis, and described by Knight ( 1900) in adequate detail to will be discussed below. Some necessary background validate the name. on plesiosaurphylogeny is therefore introduced here. , - Neotype-UW 15943 & UW 24801, a partial The phylogeny of the Plesiosauria. and of clade skeleton comprising axial skeleton, ribs, pectoral Cryptocleidoidea in particular, has undergone girdle, and forelimb elements. extensive taxonomic revision of late. Carpenter's Referred Material:UW 24215 ( 1997) assertion that the Pliosauridae as traditionally Ottarreau-Redwater Shale member of the defined was polyphyletic motivated a cladistic analysis Sundance Fonnatioo, Late Jurassic (Oxfordian); by O'Keefe (2001; see also O'Keefe in press a), who Natronaand Carbon Counties, Wyoming. found thatthe Pliosawidae contained members of three Diagnosis-A small plesiosaur with an unknown clades: the primarily Jurassic rhomaleosaurs and true number of cervical vertebrae, but probably less than pliosaurs, and the Cretaceous polycotylids. O'Keefe 31. Cervical vertebrae are much shorter than wide, are found strong support for a clade containing the not waisted, and do not have elongate articulations for Polycotylidae and the traditionally defined cervical ribs. The foramina subcentraJia are widely Cryptoclididae (including the Jurassic taxa spaced, and the rims of articular faces are poorly Cryptoclidus, Tricleidus, and Kimmerostnll"U3, as well ossified. The humerus possesses radial and ulnar as other, more derived Cretaceous fonns). O'Keefe also articulations that are subequal in length, articulations found that Muraenosaurs, often considered an for two supernumerary ossifications in the epipodial elasmosaur, was also a member of this clade. O'Keefe row, and a long. slender shaft. Thescapula possesses a (200I) therefore redefined Williston's (1925) medial process extending toward the midline but not Cryptocleidoidea to include Muraenosaurus and the contacting its neighbor, and certainly lacking a long Polycotylidae as well as other 'cryptoclidid'taxa. Given midline suture. Suture between scapula and coracoid in these relationships, the Upper Jurassic cryptocleidoid center of glenoid. Teeth narrow and recurved withlong taxa assume greater importance, because they are near roots, and striated all around. Anterior interpterygoid the base of a radiation giving rise to both vacuity present; the pterygoids behind this vacuity are plesiosauromorph and pliosauromorph taxa (O'Keefe, developed into a deep block of bone giving a distinct 2002). The bizarre and poorly-understood members of shelf to the basicranium. Pterygoid processes extend the Cimoliasauridae constitute a third lineage diverging caudally in a U-shape to effect articulation with the during this radiation. Cryptocleidoid material from basioccipital tubers. Wyoming bas the potential to shed light on the morphology and relationships of the clade at an early DESCRIPTION period in its history. This material is also biogeographically important, because Upper Jurassic Tatenectes laramiensis is represented by the cryptocleidoids are known almost entirely from following material: the neotype UW 15943 and UW Englandat present 24801, an articulated skeleton consisting of pectoral girdle, distal h�eriis, and partial axial skeleton SYSTEMATIC PALEONTOLOGY comprising nbs and dorsa] and two posterior cervical vertebrae; and UW 24215, a fragmentary skull and Suborder Plesiosauriade Blainville, 1835 articulated vertebral column. UW 15943 and UW Genus Tatenectes new genus 2480 I were collected from a Redwater Shale outcrop near Roughlock