Ornithomimus

## OrnithomimusBird Mimic

### Temporal Range

76 - 66 million years ago, Campanian - Maastrichtian Stage, Late Cretaceous Period

### Episodes

* Ice Worlds (Segment 2)
* North America (Segment 5)

## Characteristics

### Diet

Omnivore

 **Main** Segments Gallery

MainSegmentsGallery

***“ Here, within the Arctic Circle, for three months of the year, the sun barely rises. When its warmth finally returns after the long winter, feathered Ornithomimus are quick to take advantage. ”***

― **David Attenborough**, *North America*
***Ornithomimus*** (Bird Mimic) is a genus of medium-sized ornithomimid theropod dinosaur that lived in the western North America 76 - 66 million years ago, from the Campanian to the Maastrichtian stage of the Late Cretaceous Period.

It is unknown which species is depicted on Prehistoric Planet. However, given its size and how it is found in northern regions, it is likely that this is meant to be *Ornithomimus edmontonicus*, the larger of the two recognized valid species.

## Paleobiology

### Size and Physique

*Ornithomimus* is the type species of the ornithomimids, a group of small, bipedal theropods characterized by their long, toothless, beaked skulls (which may be suited for an omnivorous diet), long, slender limbs, hands that resemble those of a sloth (indicating that they may have served a similar role in hooking branches to eat), large eyes and brains, and, most famously, their ostrich-like bodies, supported by hollow bones, built for speed. *Ornithomimus*, being around 3 - 3.8 meters (10 - 12 feet) long and weighing around 170 kilograms (370 pounds), would have probably ran at around the speed of an average ostrich, which weighs around 140 kilograms (310 pounds), and can run at 70 kilometers (45 miles) per hour.

In comparison with relatives like *Struthiomimus*, *Ornithomimus* has a shorter torso, long slender forearms, very slender, straight hand and foot claws, and hand bones and fingers of similar lengths.

### Prehistoric Planet's Depiction

*Main: *Ornithomimus* on Prehistoric Planet*

Main: *Ornithomimus* on Prehistoric Planet

On Prehistoric Planet, *Ornithomimus* is shown covered in thick, gray, shaggy ostrich-like plumage and a black tuft of feathers (much like *Therizinosaurus*) resembling a human's hairstyle on their heads. Their arms are covered with pennaceous feathers (based on remains found in 1995, 2008, and 2009), black on their outer parts, red on the underside, and more prominent in older, more mature individuals, while their legs from the mid-thighs to the feet were bare, with neither scales nor feathers, as indicated by remains discovered in 2015.

*Ornithomimus* is the focus of the second segment of Ice Worlds, where a flock of males prepare nests to attract incoming females. One male, a latecomer, somehow manages to keep up by stealing nesting materials from his neighbors. When his first attempt failed, he simply stole from the nest of another. *Ornithomimus* also appears in the fifth, final segment of North America, where flocks of them quickly forage for food as the cold, dark winter season of Alaska came to an end. There, a *Nanuqsaurus* tries to catch one of them. Though she fails the first time, she eventually succeeds and shares her fresh kill with her hatchlings.

## Paleoecology

### Paleoenvironment

*Main: Horseshoe Canyon Formation, Prince Creek Formation*

Main: Horseshoe Canyon Formation, Prince Creek Formation

***“ Downstream, as the rivers broaden and begin to slow, they start to drop their loads of silt, and a network of islands appears. Some animals have already seized the moment to assemble for the spring rituals. Spring, at last, has truly arrived. ”***

― **David Attenborough**, *Ice Worlds*
*Ornithomimus* lived 76 - 66 million years ago in Laramidia, an island continent that would one day become western North America, which, by that time, was split in half by an inland sea. Remains of *O. edmontonicus* have been found in the Horseshoe Canyon Formation in southern Alberta, Canada, which by that time was an area of floodplains, estuaries, and coal swamps. Though no confirmed *Ornithomimus* remains have been found in the Prince Creek Formation in Alaska, USA (where some are shown to live in the fifth and final segment of North America), indeterminate ornithomimosaur remains in the area may indicate that it did live there after all.

### Speed

***“ These fleet-footed travelers are among the fastest runners of all dinosaurs, capable of covering vast distances in search of fresh vegetation. They're so fast, they're very difficult for predators to catch. ”***

― **David Attenborough**, *North America*
The swiftness and agility of *Ornithomimus* is useful for traversing great distances for reasons like finding food, as seen in the fifth segment of North America. Its toothless beak appears suited for omnivory, though it is believed that they preferred to feed on plants more, with their sheer abundance sometimes brought up as evidence of their herbivorous lifestyle since herbivores greatly outnumber the carnivores of their ecosystem. Even so, the threat of predation is prevalent, and while *Ornithomimus* can presumably peck, claw, and kick to defend itself, when attacked by large predators like *Nanuqsaurus*, its first and best defense is its speed, which may have primarily evolved as an adaptation to escape danger.

### Social Habits

***“ Dozens of male Ornithomimus are preparing for the most important moment of their year. These strange, ostrich-like dinosaurs choose the safety of these islands to scrape out shallow craters, the first stage in making a nest. When the females arrive, they will choose to mate with the males who made the best one. ”***

― **David Attenborough**, *Ice Worlds*
The show also depicts *Ornithomimus* as an animal that lives in flocks, based on the remains of some relatives in bonebeds. This allows for safety in numbers, which protects the many at the expense of the few who are targeted by predators, as shown in North America. Flocking behavior does have its downsides, however, when it comes to competition and resources. In Ice Worlds, a colony of male *Ornithomimuses* with the males build elaborate nests to entice females to choose them as a partner. As a result, they can get quite aggressive when it comes to defending their nests, justified by the fact that, aside from other dinosaurs coming in, mistaking their nests as vegetation to snack on, some other members of the colony would steal their hard work to build up their own nests. Similar nest material-stealing habits can be seen in penguins today.

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The thief is scared off by the individual he's stealing nesting materials from
## References

1. ↑ 1.0 1.1 1.2 1.3 *The Princeton Field Guide to Dinosaurs*
2. ↑ Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins
3. ↑ Naish, Darren (@TetZoo) (June 15, 2022) on Twitter, discussing the integument of ornithomimids, and bringing up how their great forearm feathers are more prominent in older, more mature specimens.
4. ↑ A densely feathered ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation, Alberta, Canada
5. ↑ An ornithomimosaurian from the Upper Cretaceous Prince Creek Formation of Alaska
6. ↑ Frozen Planet: Penguin's life of crime