Period: Late Cretaceous
Order, Suborder, Family: Saurischia, Theropoda, Ornithomimidae
Location: North America
Length: 13 feet (4 meters)
Struthiomimus ("ostrich mimic") is the best known of all the ornithomimids. A complete skeleton, which is now displayed at the American Museum of Natural History, was collected from the Judith River Formation of Alberta. Its name points to how similar its skeleton is to the modern Struthio (ostrich).
Like other ornithomimids, the skull was small (only ten inches long) and lightly built, and it lacked teeth and had a horny beak. Its eyes were large and it had a slender neck. Just like modern birds, the neck ribs were solidly fused (joined) to the neck vertebrae (bones of the spine). The back was stiff to support the weight of the body, long arms, and neck.
The arms were slender and the hands had three fingers. The inner finger was slightly shorter than the others. The claws at the ends of the fingers were straight and were probably not used to grasp prey. The back limbs and upper foot bones were long, as was the tail. The hands and arms were like those of a modern sloth, which uses its arms to grasp branches of trees. Because of this, some scientists think Struthiomimus may have been a herbivore that used its arms to pull branches within reach of its beak. But this dinosaur may have been omnivorous and eaten plants and whatever small animals it could catch.