Home > Diorama > Dinosaur Explorer > Ornithomimus The Ornithomimus (which literally means "speedy bird mimic") was discovered in 1889 by George Cannon near Denver, Colorado. Ornithomimus was an omnivorous dinosaur which fed on plant and animal matter including insects, small reptiles and mammals, eggs, fruits and leaves. It lived during the late Cretaceous Period, between 75 - 65 million years ago. This dinosaur is often described as "ostrich-like," and is thought to have been very fast and agile (reaching speeds of up to 43 m.p.h.), walking on its two long and slender hind legs. They measured anywhere from 15 - 20 feet in length, and approximately 6 - 8 feet in height. Ornithomimus had a toothless & horny beak, large eyes, a long neck and tail, hollow bones, and a relatively large brain (in fact, it is thought to have been among the smartest of the dinosaurs). Three Ornithomimuses can be found in the diorama at Universe of Energy and are the spitting dinosaurs which are located in the "mud pit" scene to the right side of the vehicles.