The “bird robber” better known as Ornitholestes was discovered at Como Bluff, Wyoming, and was described by Henry Osborn in 1903. Ornitholestes lived during the Late Jurassic period about 156 to 145 million years ago. At about 2 meters (6.5 ft) in length and approximately 12 kg (26 lbs) in weight, it was an average-sized theropod dinosaur. Its most distinguishing characteristic for years was the horn-like protrusion on its nose, which has since been attributed as not an actual horn or bump but an upward flare of bone that had been caused post-mortem and preserved in fossilization.
The presence of Ornitholestes on Isla Sorna is debatable, as Richard Levine was only able to make a hasty identification of an animal carcass on the Costa Rican shoreline before it was destroyed. The animal is, however, recognized as an official animal in the novel for this reason. However, the aberrant form may have actually been a Velociraptor or, given its description, a Carnotaurus. However, neither of these have been confirmed.