Ornithomimus, which means "bird mimic". And you can see why; exactly like an Ostrich.
— Allen, about Ornithomimus
in Fall of a Kingdom II: Return of the King

Ornithomimus (name meaning "Bird Mimic") is a genus of omnivorous ornithomimid theropod dinosaur that originated during the Late Cretaceous period in what is now North America. Measuring almost 5 meters long and weighing nearly 170 kilos, Ornithomimus ware herd living animals whose chicks possessed fluffy feathers and (like many modern-day birds) imprint on the first thing they see. A rare herbivorous theropod, they fed on both terrestrial vegetation and aquatic particles.

In the Series 2 premiere "Fall of a Kingdom II: Return of the King", a whole breeding colony of Ornithomimus was brought back to the park from Late Cretaceous Montana of 65 million years ago. They reside in a swamp-like enclosure.


Era & DiscoveryEdit

Ornithomimus lived in North America during the Late Cretaceous period, from 75–65 million years ago. Among the last of the dinosaurs, it died out with other dinosaurs at the end of the Cretaceous. They were also prey items for predatory dinosaurs like Tyrannosaurus and Dromaeosaurus. Ornithomimus was discovered and named by Othniel Charles Marsh in 1890.

Physical AttributesEdit

1x1 OrnithomimusEmergesFromBush

To the tip of its snout, Ornithomimus stood 7 feet (2.1 m) tall, measured 12–15 feet (3.7–4.7 m) long and weighed 167 kg (370 lbs). Medium-sized dinosaurs, Ornithomimus, like all of the "bird mimic" dinosaurs, had a somewhat atypical theropod body plan. They had long, curved necks and long arms and hands, not typical of a theropod. Also unlike other theropods, they had wrinkly pink and black beaks.

Though Ornithomimus are considered vegetarians, they occasionally ate meat, therefore, making them omnivorous dinosaurs; eating plants, meat, small reptiles and mammals, and even eggs. They were utterly the opposite of what anyone would imagine what dinosaurs to be like.

Ornithomimus chicks were covered in downy feathers which would molt by adulthood. Youngsters were a dull brown color, with a thick layer of fuzzy proto-feathers, as well as different, stouter proportions to the gangly, skinny adults. The scales of Ornithomimus were a uniform light blue, with little to no prominent patterning. The neck and head was a much brighter blue, whilst the body was more grey. Some individuals had dark speckled bodies.

With their beaks at the front, they had ridges on the inside, much like modern ducks and geese, and Ornithomimus used those to crush their food. The beaks on these creatures allow then to sieve their food, making them more like ducks than ostriches. The males also looked different from the females, with the males having a blue body appearance and the females being more grey in color.

In addition, Ornithomimus was a very fast, swift, and agile animal, capable of reaching speeds as fast as 40 mph, as fast as an Ostrich, which allowed them to outrun even the fastest predators. However, some Ornithomimus were not so lucky.

Behavior & TraitsEdit

1000px-1x3 OrnithomimusCheckingOnEggs
Like many dinosaurs of their size and overall appearance, Ornithomimus was a highly social omnivore that lived in flocks composed of more than 20 individuals. Like many modern social animals and some other dinosaurs, such as the small ornithopods, one Ornithomimus adult would be on sentry duty whilst the others fed and played, in order to look out for predators. This was an important job, as larger, more carnivorous theropods, like Dromaeosaurus and Tyrannosaurus, preyed on Ornithomimus flocks. Despite the vast numbers of individuals in a flock, they would still flee from danger. When chased by a large predator, Ornithomimus flocks would devolve into disorganized stampedes. 

In addition, whenever they were breeding, Ornithomimus had much in common with large modern birds, like ostriches. The females would distance themselves, breaking off from the rest of the flock to make a nest. A number of light blue oval-shaped eggs were laid in a circle within a large nest. Unlike with ostriches, the mother watched aggressively over the eggs alone, with no help. Ornithomimus females were also very protective of their eggs and would lay around ten eggs. However, for any egg that rolled out of the nest, the mother would sacrifice at least two eggs to feed predators. The eggs required more heat than crocodile and bird eggs in order to hatch. Ornithomimus chicks were curious and inquisitive animals and would imprint on and follow the first thing they saw, usually their mother.

Despite their close resemblance to ostriches, Ornithomimus behaved more like ducks. They preferred to live near lakes and ponds rather than forests or open plains. In fact, their mouths had the texture of sandpaper and were used more like sieves than beaks. Like ostriches, Ornithomimus would calm down if their eyes were concealed by some method, such as by putting a bag or sock over their head.

Journal Entry Edit

An ostrich-like dinosaur regarded for its cheetah-like speed and first discovered in dig sites located in Colorado, Ornithomimus ("Bird Mimic") is a bird-like dinosaur that lived across North America during the Late Cretaceous period. One of the largest known ornithomimids, measuring over 4 meters long, Ornithomimus has large eyes, no teeth (rather duck-like bills), forelimbs and longer claws than most other genera of its type. They are social creatures and both tend and prefer to live in large flocks that roam grasslands.

Though being in the open might seem dangerous, it reduces the chances of predators being able to sneak up on them. Large flocks can even drive off attackers with sheer numbers. Conversely, running away is easier if there's nothing in their path, and Ornithomimus are fast, able to run at 40 mph. But when it’s time to eat, they prefer somewhere a bit less exposed. Though born to run free on the plains, Ornithomimus graze upon the small ferns that grow inside conifer forests.

The long legs of Ornithomimus are good for more than just marathon sprinting. A set of powerful thigh muscles give this unassuming herbivore a savage kick, with enough force to kill smaller predators, such as Velociraptor, Troodon, and Dromaeosaurus. However, for a lone Ornithomimus attacked by anything much bigger than a Deinonychus...running would be a good idea.

— Allen, in his journal about Ornithomimus



  • The sound effects of Ornithomimus are that of donkey, duck, elk, emu, flamingo, goose, ostrich, vulture, and zebra sound effects.
  • Ornithomimus is one of the two ornithomimid dinosaurs brought into the park, the other being Gallimimus.
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