Zanabazar, Norell & Makovicky & Bever & Balanoff & Clark & Barsbold & Rowe, 2009

Norell, Mark A., Makovicky, Peter J., Bever, Gabe S., Balanoff, Amy M., Clark, James M., Barsbold, Rinchen & Rowe, Timothy, 2009, A Review of the Mongolian Cretaceous Dinosaur Saurornithoides (Troodontidae: Theropoda), American Museum Novitates 3654, pp. 1-64 : 26-27

Zanabazar , new genus

TYPE SPECIES: Zanabazar junior ( Barsbold, 1974) .

DERIVATION OF NAME: In honor of Zanabazar (1635–1723), the first Bogd Gegen of Mongolia.

INCLUDED SPECIES: Type species only .

LOCALITY AND AGE: Nemegt Formation at Bugiin Tsav, Omnogov Aimag, Mongolia (figs. 2, 21). The Nemegt Formation overlies the Djadokhta Formation and is considered to be Maestrichtian based primarily upon the vertebrate fauna ( Jerzykiewicz and Russell, 1991).

DIAGNOSIS: Differs from Saurornithoides mongoliensis and most other troodontids (save Troodon formosus ) in lacking a small depression on the lateral wall of the braincase just dorsal to the trigeminal foramen. The holotype of Zanabazar junior is the largest published troodontid specimen (midline length of the skull 5 272 mm), and is substantially larger than most other troodontid species. Only Troodon formosus appears to approach it in size. Differs from Troodon formosus in having a more ovoid-shaped foramen magnum, a posttemporal fenestra that is enclosed by an almost equal proportion of the exoccipital/opisthotic and squamosal (this same feature in Troodon formosus is formed almost entirely by the exoccipital/opisthotic), a deeper paroccipital process resulting in a different positon of the posttemporal fossa relative to the foramen magnum, and the lack of an osseous signature of the ophthalmic branch of the trigeminal nerve (CN V) in the laterosphenoid.