|(unranked):||Disputed, either Coelurosauria or Tetanurae|
|Superfamily:||Disputed, either Allosauroidea (based on Gregory Paul) or Tyrannosauroidea|
|Family:||Disputed, either Ornitholestidae or Coeluridae|
O. hermanni Osborn, 1903 (type)
Ornitholestes (meaning "bird robber") was a small theropod dinosaur of the late Jurassic of Western Laurasia (the area that was to become North America). To date, it is known only from a single partial skeleton, and badly crushed skull found at the Bone Cabin Quarry near Medicine Bow, Wyoming, in 1900. It was described by Henry Fairfield Osborn in 1903. An incomplete hand was later attributed to Ornitholestes, although it now appears to belong to Tanycolagreus. The type (and only known) species is O. hermanni. The species name honors the American Museum of Natural History preparator Adam Hermann.
Ornitholestes was roughly 2 meters (6.5 ft) in length. The head of Ornitholestes was relatively small. Nonetheless, the skull was more robust than that of many other small theropods, such as Compsognathus and Coelophysis, and this would have enabled Ornitholestes to deliver a powerful bite.
Gregory S. Paul suggested the presence of a small horn on the snout of Ornitholestes, similar to that of Proceratosaurus. however this has recently been disproved by Carpenter et al., which indicated that the 'crest' was actually a broken nasal bone. Like most other theropods, Ornitholestes had a long tail, presumably used for balance.
Present in stratigraphic zone 2. Remains possibly referrable to Stokesosaurus have been recovered from stratigraphic zone 5 of the Morrison Formation.
The sharp teeth of Ornitholestes clearly identify it as a carnivore, but its exact diet has been a subject of debate in the paleontological community.
In his original 1903 description, Henry Fairfield Osborn suggested that Ornitholestes might have preyed on contemporary birds, based on the "rapid grasping power of agile and delicate prey" suggested by the structure of the hand. In 1917, however, Osborn reevaluated the hand and determined that it was unsuitable for this purpose.