Gallimimus ("chicken mimic"} was an ostrich-like dinosaur which existed in southern Mongolia during the Upper Cretaceous period. It was one of the largest ornithomimosaurs, reaching a maximum length of 4 meters (13 feet). It was a omnivorus dinosaur.
Gallimimus is one of the fastest dinosaurs. They had small heads, large eyes, large brains, long necks, short arms, long legs, and long tails. They had hollow bones, like a bird. Ornithomimosaurs were unique among the theropods with their toothless beaks, which may have indicated that they were herbivores or omnivores.