By | September 9, 2016

Also known as “ostrich dinosaurs,” the members of the ornithomimid family were built like ostriches and were just as quick on their feet. They were the fastest dinosaurs of all, capable of reaching perhaps 50 mph (80 kph) when running. They evolved from flesh-eaters, but their birdlike beaks and lack of big teeth suggest a more varied diet.


Key features
■ Extremely long legs
■ Long necks and small, beaked heads
■ Large eyes
■ Tiny teeth or no teeth

Ornithomimids first appeared in the Early Cretaceous, 130 million years ago. They died out in the Late Cretaceous, 65 million years ago.

Gallimimus (GAL-ih-MIME-us)


When: 75–65 million years ago (Late Cretaceous)

Fossil: location Mongolia

Habitat: Desert plains

Length: 20 ft (6 m)

Diet: Leaves, seeds, insects, and small animals

One of the best known of all ornithomimids is Gallimimus (“chicken mimic”). It was the largest ornithomimid, three times as tall as a man and, at 1,000 lb (450 kg) in weight, a lot heavier than any chicken.
Gallimimus was the fastest sprinter of any dinosaur and could have outrun a racehorse. It had a birdlike skull, with a brain about the size of a golf ball (only slightly larger than an ostrich’s). Its long, toothless beak was used to pick up leaves, seeds, insects, and small mammals.



Gallimimus had wide eye sockets with eyes facing sideways. This helped it spot enemies in almost any direction. Inside each eyeball was a supporting ring of small bony plates. Modern birds still have this feature.

Struthiomimus (STROO-thee-oh-MIME-us)


When: 75 million years ago (Late Cretaceous)

Fossil location: Canada

Habitat: Open country, riverbanks

Length: 15 ft (4 m)

Diet: Omnivorous

Struthiomimus was so similar to Ornithomimus that its fossil was for many years thought to be that of Ornithomimus. The only difference is that it had longer arms with stronger fingers. At the ends of its fingers were long, straight claws, but it probably could not use them to grasp prey, like Ornithomimus did.
Instead, like modern sloths, Struthiomimus may have used its arms and hands to pull tree branches within reach of its beak. It probably ate buds and shoots from trees and other plants, but its diet may also have included small animal sand insects.
Like other ornithomimids, Struthiomimus had long, powerful legs built for speed, and a small head perched on a slender, flexible neck.

Ornithomimus (OR-nith-oh-MIME-us)


When: 75–65 million years ago (Late Cretaceous)

Fossil location: USA, Canada

Habitat: Swamps, forests

Length: 10 ft (3 m)

Diet: Omnivorous

Ornithomimus had the typical short body and long back legs of an ornithomimid. A fast runner, it could make sudden turns even while sprinting by swinging its tail from side to side. For its size and time, it had a fairly large brain, but was far less intelligent than an ostrich.



An Ornithomimus represented with feathers

Most models and artworks show ornithomimids with scaly skin. However, many scientists now believe they had primitive, fuzzy feathers (“protofeathers”), in common with closely related dinosaur families.




Ornithomimids may have run just like ostriches run today. Ostriches take great strides with their powerful, long legs, with their tails jutting out behind. The fastest bird today, an ostrich can run at about 45 miles (72 km) per hour, while an average human can reach only 6–11 mph (10–18 kph).


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