Abstract from Nichollsemys baieri gen. et sp. nov, a Primitive Chelonioid Turtle from the Late Campanian of North America, by D. Brinkman, M. Hart, H. Jamniczky and M. Colbert, 2006 (Paludicola 5:111-124):

       We describe Nichollsemys baieri gen. et sp. nov., a primitive non-protostegid chelonioid turtle from        the late Campanian Bearpaw Formation of Alberta, Canada, and DeGrey member of the Pierre Shale of        South Dakota, USA. Known only from skull morphology, Nichollsemys baieri is phylogenetically        intermediate between Toxochelys Cope, 1873, and Ctenochelys Zangerl, 1953. It is similar to Toxochelys        and primitive with respect to Ctenochelys in the presence of a narrow triturating surface that does        not incorporate the vomer, a large foramen palatinum posterius, and a well-developed processus        pterygoideus externus on the pterygoid. It is derived relative to Toxochelys in features of the        braincase, including the presence of a reduced area of exposure of the basisphenoid on the ventral        surface of the braincase, a mid-ventral ridge on the palate extending between the basisphenoid and        vomer, a rod-like rostrum basisphenoidale, a mid-line ridge extending from the foramen anterior        canalis carotici interni to the dorsum sellae. It also differs in that the foramen caroticum laterale is        larger in diameter than the foramen anterior canalis carotici interni.

This specimen, the holotype, was collected from glacial till (most likely derived from the Bearpaw Formation) along Chin Coulee, south of Taber, Alberta. It was made available to the University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Donald Brinkman of the Royal Tyrrell Museum of Palaeontology. Funding for scanning was provided by Dr. Brinkman. Funding for image processing was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Timothy Rowe of The University of Texas at Austin.

Lateral view of skull	Dorsal view of skull	Ventral view of skull

The specimen was scanned by Matthew Colbert on 17 November 2004 along the horizontal axis for a total of 317 512x512 pixel slices. Each slice is 0.25 mm thick, with an interslice spacing of 0.25 mm and a field of reconstruction of 135 mm.

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