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A partial ornithomimid braincase from Ukhaa Tolgod (Upper Cretaceous, Mongolia)

by: Makovicky, Peter J

Publication date: 1998

Topics: Ornithomimidae, Dinosaurs, Reptiles, Fossil, Skull, Paleontology, Ornithomimidae -- Mongolia -- Ukhaa Tolgod, Dinosaurs -- Mongolia -- Ukhaa Tolgod, Reptiles, Fossil -- Mongolia -- Ukhaa Tolgod, Paleontology -- Cretaceous -- Mongolia -- Ukhaa Tolgod, Paleontology -- Mongolia -- Ukhaa Tolgod

Publisher: New York, NY : American Museum of Natural History

Collection: americanmuseumnaturalhistory; biodiversity

Contributor: American Museum of Natural History Library

Language: English

Rights: http://biodiversitylibrary.org/permissions

Rights-holder: American Museum of Natural History Library

Volume: no. 3247

16 p. : 26 cm

"Among the dinosaurian remains recently discovered by the Mongolian Academy of Sciences-American Museum of Natural History expeditions at the Ukhaa Tolgod locality (Southeastern Gobi Desert, Mongolia) are a partial braincase and cervical vertebrae of an ornithomimid dinosaur (IGM 100/987). This specimen represents the first record of an ornithomimid from this rich locality, as well as the first discovery of such an animal in Djadokhta-like beds. Although broken and slightly distorted, the preserved portion of the braincase reveals new information on the anatomy of ornithomimids. The middle ear region is enlarged and is connected to three expansive tympanic pneumatic systems as in other advanced theropods. The hypoglossal nerve (cranial nerve XII) is divided into three branches, a feature otherwise known among nonavialan coelurosaurs only in Troodon formosus. Several autapomorphies of the Ornithomimidae are preserved in IGM 100/987, including expansive pneumatization of the basioccipital-exoccipital region dorsal to the basal tubera and a large depression of the posterior face of the quadrate shaft. IGM 100/987 displays subtle differences from North American ornithomimid taxa and Gallimimus bullatus, but a more definite taxonomic assessment must await a thorough revision of ornithomimid phylogeny"--P. [1]

Title from caption

"November 5, 1998."

Includes bibliographical references (p. 15-16)

Abstract: 'Among the dinosaurian remains recently discovered by the Mongolian Academy of Sciences-American Museum of Natural History expeditions at the Ukhaa Tolgod locality (Southeastern Gobi Desert, Mongolia) are a partial braincase and cervical vertebrae of an ornithomimid dinosaur (IGM 100/987). This specimen represents the first record of an ornithomimid from this rich locality, as well as the first discovery of such an animal in Djadokhta-like beds. Although broken and slightly distorted, the preserved portion of the braincase reveals new information on the anatomy of ornithomimids. The middle ear region is enlarged and is connected to three expansive tympanic pneumatic systems as in other advanced theropods. The hypoglossal nerve (cranial nerve XII) is divided into three branches, a feature otherwise known among nonavialan coelurosaurs only in Troodon formosus. Several autapomorphies of the Ornithomimidae are preserved in IGM 100/987, including expansive pneumatization of the basioccipital-exoccipital region dorsal to the basal tubera and a large depression of the posterior face of the quadrate shaft. IGM 100/987 displays subtle differences from North American ornithomimid taxa and Gallimimus bullatus, but a more definite taxonomic assessment must await a thorough revision of ornithomimid phylogeny'--P. [1].