CONRAD, J.L.; Univ. of Chicago: Morphology of Shinisauridae Compared with Other Anguimorpha (Squamata, Reptilia).

Despite recent cladistic work, the interrelationships of the major anguimorph lineages (Carusioidea, Anguioidea, and Platynota) remain uncertain. Repeated errors concerning the anatomy of Shinisaurus significantly contribute to systematic difficulties. I discuss the published anatomical errors concerning Shinisaurus, its similarities with an unnamed Eocene fossil, and compare both with other anguimorph groups. Contrary to previous publications, Shinisaurus lacks the following carusioid or xenosaurid synapomorphies; reduction of the internasal contact, constricted frontals, a jugal-squamosal contact, and subconical cephalic osteoderms. Cephalic osteoderms are present, but flat in Shinisaurus. Accounts reporting five cervical vertebrae and fewer than 25 presacral vertebrae are also erroneous. Shinisaurus possesses eight cervical vertebrae and variably 26 or 27 presacral vertebrae. An unnamed fossil anguimorph from the Green River Formation of Wyoming does not preserve cephalic osteoderms, but otherwise matches Shinisaurus in these characters. Additionally, both share small interlocking tabs of the frontal and parietal, a narial extension of the prefrontal, a robust dermal rugosity and subpalpebral fossa on the prefrontal, and non-imbricate, keeled, tail osteoderms. Shinisauridae is resurrected to receive Shinisaurus and this fossil. Shinisaurids share with Platynota the dorsal parietal attachment of jaw adductors, a posteriorly reduced splenial, and expanded marginal tooth bases. Carusioidea and Shinisaurus share a reduced entocarotid fossa. Anguioidea and Shinisaurus share a narrow interpterygoid vacuity. Anguioidea, Platynota, and Shinisaurus share small premaxillary teeth. The morphology of the Shinisauridae suggests platynotan affinities.