Chirostenotes Oviraptorosaur Dinosaur Limb Bone from Hell Creek

Description: The bird-like Chirostenotes was about as large as a grown human but weighed much less owing to its slender, sleek build. Chirostenotes’s hands were long and slender and earning it its name, which means "narrow hand." These adaptations enabled Chirostenotes to move very quickly and strike at prey before they knew of danger.

This little dinosaur was about 7 feet in length and 3.5 feet in height. Its weight is has been estimated as low as 20 kg to as high as 50 kg. It was primarily a carnivore, but may have been omnivorous to some extent. The diet of Chirostenotes largely consisted of small game such as lizards and fish. It may have also eaten eggs. Chirostenotes walked upright on two legs. The snout was long and tapering. It had a high and rounded crest on top of its head.

Chirostenotes had three thin clawed fingers on each hand. The middle finger was longer than the other two. Its hands were well suited for grabbing fish. There were two pleurocarpals (openings in the sides) in each vertebra. The jaw had a symphysial (made of bones grown together) ridge. The openings called pleurocoels in the vertebrae may have been used as an air sac system, one which is similar to that in modern birds; in birds the vertebrae have a series of air sacs which are connected to the lungs. This fossil is a portion of the radius (lower arm bone) of this unusual dinosaur.