Name: Bagaraatan ostromi
Etymology: From Mongolian baga meaning "small", and araatan meaning "predator", and in honour of Dr. John H. Ostrom.
Distribution: Late Cretaceous (Campanian-Maastrichtian, 83.5 - 65.5 Ma) of Ömnögovi, Mongolia
Type Specimen: Caudal vertebrae, fragmentary left mandible, pelvis, tibia, fibula, pedal phalanges and femur.
The caudal (tail) vertebrae of B. ostromi are strongly fused, restricting horizontal and vertical movement, thereby making the tail very rigid. As the tail was also relatively muscular, it is likely that it acted not solely as a counter balance, but was the result of modification for increased running speed. Relative to its overall body size, and when compared to other similar sized therapods, the skull and hindlimb of B. ostromi are quite slender. All the above evidence suggests that B. ostromi was a long legged, agile, fast moving predator.
Osmólska, H. 1996. An unusual theropod dinosaur from the Late Cretaceous Nemegt Formation of Mongolia. Acta Palaeontologica Polonica, 41(1):1-38.