Kingdom Animalia
Phylum Chordata
Superclass Tetrapoda
Class Reptilia
Subclass Diapsida
Superorder Dinosauria
Order Saurischia
Suborder Theropoda
Superfamily Ornithomimoidea
Family Ornithomimidae
Genus Ornithomimus
1st Species Ornithomimus velox
2nd Species Ornithomimus edmontonicus
Other attributes
Time Range 76.5-66 mya
Location United States of America, Canada
Name Meaning Bird mimic
Physical Dimensions 3.1 meters long for O.velox; 3.8 meters for O.edmontonicus
Dietary Classification Herbivore (presumed omnivore)

Ornithomimus is an ornithomimid theropod dinosaur from the Late Cretaceous of the United States of America and Canada. It was named in 1890 by Othniel Charles Marsh. It was one of the most unique early-discovered theropods to exist, due to its build and lifestyle; like the earliest discovered dinosaurs, Megalosaurus and Iguanodon, and all the other the earliest discovered Mesozoic reptiles, Pterodactylus, Rhamphorhynchus, Mosasaurus, Plesiosaurus and Ichthyosaurus, it was a wastebasket taxon, and many other ornithomimid remains similar to it were proved to be their own genus.


Ornithomimus was a very birdlike theropod, hence the meaning of its name, "bird mimic". It had long legs, a long tail, long, slender arms with moderately small hands, a moderately long neck, and an elongated, bird-like head with large eyes and a toothless beak. Most of its body (excluding most of its legs and all of its beak) would have been covered in short, fuzz-like feathers; however, its arms would have had long, vaned feathers, similar to all other advanced theropods.


Ornithomimus would have been an herbivore, feeding on leaves and fruits by grabbing them with its beak before swallowing them, and using its sloth-like arms to pull down branches before feeding on vegetation growing off of them. However, some may speculate that it, like most herbivorous birds, would have also supplemented its diet with animal protein, snacking on insects, crustaceans, lizards, small mammals, and eggs from time to time.


Ornithomimus's long legs allowed it to run at swift speeds, making it one of the fastest dinosaurs. During its time, the top predators were the tyrannosaurs, giant carnivorous theropods with bone-crushing jaws, small arms, and bulky builds. Due to the very latter, they were somewhat slow predators, so in order to capture swift prey like Ornithomimus, they would have to ambush it; however, combined with its tremendous speed, it had big eyes on a head held up by a long neck, so it could see dinosaurs over sparse vegetational cover, making the task of sneaking up on it a rather hard one. A comparison of its sclerotic rings to those of modern reptiles and birds indicates that it was cathemeral.

In popular cultureEdit

Ornithomimus was first introduced to the public in the Rite of Spring segment of the 1940 Disney musical movie, Fantasia. Since then, it has become extremely popular, appearing in major pieces of media like The Valley of Gwangi and Prehistoric Park. An interesting thing to note is that during the early 1900s, most theropods, such as Tyrannosaurus and Allosaurus, were depicted as sluggish reptilian giants with tails dragging on the ground. Ornithomimus, however, was depicted as having a bird-like posture with an erect tail; this also happened to its close relative, Struthiomimus.

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