This is the animal that gave rise to the term ‘ostrich mimic’, which is often used instead of the slightly more formal ornithomimid. It was the first complete ornithomimid skeleton to be found. It was a fast runner on the late Cretaceous plains of North America. Its main predators would have been sickle-clawed deinonychosaurs and the tyrannosaurid Albertosaurus, from which it would have escaped by a sudden turn of speed.
Fast-moving Struthiomimus may have looked like a large bird, but it did not have wings or feathers and didn’t fly. It ran on its two long back legs, gripping the ground with the curved claws on its toes.
Struthiomimus used its long thin, stiff tail to balance itself. It had two short, slim arms and long, three-fingered hands, which it probably used for reaching and picking up food.
Name: Struthiomimus, meaning ‘ostrich mimic’
Size: 3-4.3m long and 2m high
Food: plants, seeds, fruits, eggs and lizards
Lived: 80-66 million years ago in the Cretaceous Period in western North America
The small head, lack of teeth, long neck, compact body and long legs are the ostrich-like features of this dinosaur. Its non-ostrichlike features are its long arms with three-fingered hands, and the long tail. It is very similar to its close relative Ornithomimus, the main differences being its slightly smaller size and longer tail. Nevertheless, many scientists regard it, along with many other genera of ornithomimids, as merely a species of Ornithomimus. Stomach stones have been associated with the skeleton. Usually only herbivores have them, so this find indicates that Struthiomimus was partly vegetarian.
Struthiomimus ate many things, including plants, seeds, nuts and fruits. It snapped at flying insects with its toothless, horny beak and consumed small ground creatures, such as lizards. It may even have raided the nests of other dinosaurs, to eat eggs and even the newly hatched young.
These fast-running dinosaurs had no weapons to defend themselves, so they travelled in groups for safety. If Struthiomimus was attacked by other dinosaurs, it fled. It was a very fast runner and could sprint at speeds of up to 40km/h over short distances, so could probably outrun most large predators.
Although the specimen of Struthiomimus was fairly complete, it was quite badly damaged, resulting in the ongoing confusion as to whether or not it is really a species of Ornithomimus.