Size and Weight:
A close relative of Ornithomimus, which it closely resembled, Struthiomimus ("ostrich mimic") galloped across the plains of western North America during the late Cretaceous period. This ornithomimid ("bird mimic") dinosaur was distinguished from its more famous cousin by its slightly longer arms and stronger fingers, but because of the position of its thumbs it couldn't grasp food quite as easily.
Like other ornithomimids, Struthiomimus pursued an opportunistic diet, feeding on plants, small animals, insects, fish or even carrion (when a kill was left unattended by other, larger theropods). This dinosaur was probably capable of short sprints of 50 miles per hour, but had a less taxing "cruising speed" in the 30 to 40 mph range.