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A review of the Mongolian Cretaceous dinosaur Saurornithoides (Troodontidae, Theropoda). (American Museum novitates, no. 3654)

Show simple item record Norell, Mark. Makovicky, Peter J. Bever, Gabe S. Balanoff, Amy M. Clark, James Matthew, 1956- Barsbold, Rinchin. Rowe, Timothy, 1953- 2009-07-09T17:03:06Z 2009-07-09T17:03:06Z 2009
dc.description 63 p. : ill. (1 col.), 1 map ; 26 cm. "June 25, 2009." Includes bibliographical references (p. 60-62). en
dc.description.abstract We review the morphology, taxonomy, and phylogenetic relationships of the Upper Cretaceous Mongolian troodontid Saurornithoides. Saurornithoides mongoliensis is known only by the holotype from Bayan Zag, Djadokhta Formation. This specimen includes a nearly complete, but weathered, skull and mandibles, a series of dorsal, sacral, and caudal vertebrae, and a partial pelvic girdle and hind limb. Saurornithoides junior, here referred to Zanabazar, also is known only by the holotype from Bugiin Tsav, Nemegt Formation. This specimen consists of a skull and partial mandible, a series of sacral and caudal vertebrae, a partial pelvic girdle, and the distal part of the right hind limb. Saurornithoides + Zanabazar is one of the few Mongolian taxa known from both the Djadokhta and Nemegt formations. The monophyly of Saurornithoides + Zanabazar has not been seriously questioned historically, yet empirical support for this clade is currently tenuous. A privileged phylogenetic relationship between Saurornithoides, Zanabazar, and the North American troodontid Troodon formosus is supported by numerous characters including the presence of a subotic recess, lateroventrally projecting and hollow basipterygoid processes, a lacrimal whose anterior process is significantly longer than its posterior process, a highly pneumatized parasphenoid rostrum, a constricted neck of the occipital condyle, a symphyseal region of the dentary that is slightly recurved medially, and an obturator process located near the middle of the ischiadic shaft. CT data for the skulls of both species facilitated a description of the endocranial anatomy of Saurornithoides mongoliensis and Zanabazar junior, including a reconstruction of the endocranial space of Zanabazar junior. Despite being the largest of the known troodontid species, the endocranial volume of Zanabazar junior is considerably smaller than that estimated for Troodon formosus, suggesting that the extremely high encephalization quotient of Troodon formosus may be autapomorphic among troodontids. en
dc.description.sponsorship American Museum of Natural History. en
dc.format.extent 47956586 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.relation.ispartofseries American Museum novitates, no. 3654. en
dc.subject Saurornithoides. en
dc.subject Troodon. en
dc.subject Dinosaurs. en
dc.subject Mongolia. en
dc.title A review of the Mongolian Cretaceous dinosaur Saurornithoides (Troodontidae, Theropoda). (American Museum novitates, no. 3654) en
dc.title.alternative Review of Saurornithoides. en

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  • American Museum Novitates
    Novitates (Latin for "new acquaintances"), published continuously and numbered consecutively since 1921, are short papers that contain descriptions of new forms and reports in zoology, paleontology, and geology. New numbers are published at irregular intervals.

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