ORNITHOLESTES

small, lightly built dinosaur found as fossils in Late Jurassic deposits (i.e., those 144 to 163 million years old) of North America and belonging to the order Saurischia, suborder Therapoda. Ornitholestes is relatively well known from a complete skeleton found in Wyoming. It was about 2 m (6 feet) long. The skull, neck, and tail were long, and the neck was apparently very flexible. The forelimbs were well developed and ended in three clawed fingers that were longer and slimmer than were common in dinosaurs, indicating that Ornitholestes could catch quick-moving and elusive prey. It has been suggested that Ornitholestes may have preyed upon the early birds, hence the name, which means bird robber, but it is equally probable that it ate small, speedy lizards and even early mammals. The hind limbs were well developed, with strong running muscles; Ornitholestes was a biped capable of rapid movement, running with the neck and tail outstretched as counterbalances to the body. It is probable that Ornitholestes, a small, active predator, filled an ecological niche that was later filled by mammals. Ornitholestes probably inhabited forest undergrowth in the Late Jurassic of North America. Some authorities equate Ornitholestes and Coelurus.