Caenagnathids popped up on the North American Cretaceous land in, if it is accurate that Microvenator celer (small hunter) represents the primitive sister taxon of all other Oviraptorids, the Cloverly Formation (approximately 107MYA). The original specimen, the type (AMNH3041) consists of minimal material including a partial skull, numerous vertebrae, left hand, arm, foot and leg, a couple ribs, and its pelvis. The original collection, unearthed by Barnum Brown in 1933 (not published, though Mackovicky and Sues did publish his illustrations for the first time in 1998) included several large carnivorous teeth that have been since attributed to Deinonychus. In 1970 John Ostrom, who had worked the previous year on publishing his description of Deinonychus, named and described Microvenator from the type specimen. Microvenator is, therefore, another example, like its later cousins Chirostenotes, an animal which was described using minimal material. It looks rather fluffy though, hardly like a killer, however, it was estimated at approximately 10 feet long as an adult; the type specimen is thought to be a 4 foot long juvenile.