Name Meaning: Bird Mimic
Geologic Era: Late Cretaceous
Estimated Range: North America
Location Found: N/A (specimen is a cast)
Size: Up to 3.8 meters long
Extinction Date: 66 million years ago
This is a replica of an Ornithomimus pedal (foot) claw. This group of dinosaurs, the Ornithomimids, are called so because they superficially resemble a modern ostrich. They were the speedsters of the dinosaur world, and any potential predators would have had a difficult time catching them. Any predator that did manage to catch an Ornithomimus would also have to contend with the foot claws as well. Some Ornithomimids were able to strike with their rear legs, in the manner of a modern cassowary. These claws, combined with the leg strength of Ornithomimus, could have inflicted serious injuries on an adversary.
In addition to long legs, Ornithomimus also had very large, well developed eyes. It is possible that Ornithomimus could see very well at night, another factor that would have put potential predators at a disadvantage. Ornithomimus could have easily outrun an adult tyrannosaur. Ornithomimus’ only serious predators would have been animals such as juvenile tyrannosaurs and dromaeosaur theropods (such as Acheroraptor and the newly discovered Dakotaraptor). These animals would have been the closest match to Ornithomimus in terms of speed, though the predator would probably still lose in a prolonged chase.
The only real chance a predator had against Ornithomimus would be ambush, though Ornithommimus’ height and keen eyesight would have made this a difficult proposition at best. There is also evidence that Ornithomimus and its relatives possessed feathers, a trait increasingly seen in dinosaurs. How much feathering is still up to debate, though a few specimens of Ornithomimus-like animals possessed quill knobs or downy feathers.
The diet of Ornithomimus is still a bit of a mystery. Its beaked mouth did not have any teeth, and so would not have been able to grasp prey or chew food items. That means that whatever food Ornithomimus could get a hold of had to be swallowed whole. A few possibilities include a plant-based diet of leaves and berries. This would have not been difficult for Ornithomimus, as its height would put a lot of succulent plant matter in easy reach. It also may have preyed upon small lizards, insects, and mammals, though again, these animals would have to be swallowed whole.
A clue might lie in the hand and arm structure of Ornithomimus. The hands in particular are very well developed for grasping items. Ornithomimus could easily have picked up and held onto small objects such as animals or eggs. It is most likely that Ornithomimus was a generalist feeder, eating nearly everything it could gets its hands or beak on. This way, it would have avoided competition with more specialized animals such as hadrosaurs and ceratopsians, both of which shared Ornithomimus’ environment.
Full Skeleton: By Eduard Solà – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=21099012
Life Restoration: http://spinops.blogspot.com/2012/12/ornithomimus-edmontonicus.html