Saniwa

Abstract: Saniwa ensidens is a pivotal taxon for understanding varanid evolution. A complete specimen of Saniwa ensidens was recently described, offering important new insights into the morphology of this taxon. We apply these new data to a broader-scale study of squamate relationships in order to understand the phylogenetic position of Saniwa ensidens and of varanids more generally. Among the other fossils included in our analysis were the Eocene taxon ‘‘Saniwa’’ feisti, the Miocene Varanus rusingensis, and the giant Pleistocene varanid Megalania prisca. We compare the phylogenetic hypothesis from our analysis of morphology with a recent molecular-based hypothesis and find numerous differences in the phylogenetic relationships within Varanus .W e constrained our morphological data set to the phylogenetic pattern presented by the molecular data to further analyze the possible phylogenetic relationships of the fossil taxa. Our analyses show that Saniwa ensidens is the sister taxon to crown-group Varanus and that ‘‘Saniwa’’ feisti is a basal member of the varanid lineage, not closely related to Saniwa ensidens. Both Varanus rusingensis and Megalania prisca are members of the crown radiations of Varanus.

Abstract: briefly described ^ as Saniwa ensidens. The type specimen was deposited in the United States National Museum, where it has remained in the same unprepared condition as originally received 50 years ago. It was preserved in a considerable number of blocks of ash-colored rock, the only evidence of the embedded specimen being two vertebrae, which had been uncovered, and the numerous bones which protruded from the broken faces of the

Abstract: Three vertebrae of a large varanid lizard from the early Eocene Andarak 2 locality in Kirghizia are described. The sacral and proximal postsacral vertebrae are each characterized by a short dorso-ventrally deep centrum and a neural arch lacking the neural spine. The material is assigned to ? Saniwa sp., probably representing a new taxon of Varanidae.

Abstract: During the field season of 1870, F. V. Hayden collected a number of sandstone blocks that contained the remains of a large fossil lizard (Middle Eocene Bridger Formation, Sweetwater County, Wyoming). Though mostly unprepared, the visible bones were described by Leidy (1870) as Saniwa ensidens (USNM 2185; holotype). Fifty years later all the blocks associated with USNM 2185 were prepared prior to Gilmore's (1922) more complete description of Saniwa ensidens and his assignment of the taxon to the Varanoidea. Gilmore (1922) notes that the skeletal remains in the blocks were partially disarticulated to dissociated despite the excellent articulation of some components (e.g., palatal elements and right and left maxillary fragments [Gilmore, 1922, p. 809; pl. 1). Gilmore (1928) altered the diagnosis of Saniwa ensidens (USNM 2185) by adding characterizations of a premaxilla, right and left anterior maxillary fragments, and anterior tips of the dentaries. Gilmore (1928, p. 57) stated that these missing elements were found after further preparation of the blocks when the type specimen was mounted for display. Re-examination of the reconstructed and mounted skull of the holotype of Saniwa ensidens (USNM 2185) has revealed characteristics of the premaxilla, premaxillary teeth, and anterior maxillary fragments and teeth, indicating that these elements belong to an entirely different family of lizards. Hence, Gilmore's (1928) association of this material with Saniwa ensidens is incorrect. I report here on the morphology and classification of these re-identified tooth-bearing elements as those of a xenosaur, and provisionally refer the elements to the Eocene xenosaur Restes (see Gauthier, 1982). The holotype specimen of Saniwa ensidens USNM 2185 was removed from display during the summer of 2000. Re-preparation of the specimen was not permitted. Specimen drawings were made using a microscope with camera lucida attachment. Photographs were taken using a Nikon camera. Measurements …