Ornithomimus

*Ornithomimus velox*

* Timothy Bradley Artwork
* Robert F Walters Artwork

***Ornithomimus*** ("bird mimic") is a genus of ornithomimid dinosaur from the Late Cretaceous Period (70-65 mya) of what is now North America.

In 1890 *Ornithomimus velox* was named by Othniel Charles Marsh on the basis of a foot and partial hand from the Maastrichtian Denver Formation. Another seventeen species have been named since. Most of these have subsequently been assigned to new genera or shown to be not directly related to *Ornithomimus*. The best material of species still considered part of the genus has been found in Canada, representing the earlier Edmontonian-age *Ornithomimus edmontonicus* (Sternberg 1933), known from several skeletons. However, on some of these the new genus *Dromiceiomimus* including *Dromiceiomimus brevitertius* (Parks 1926) has been based, causing taxonomic problems of priority and identity that are still unresolved. *Ornithomimus* was a swift bipedal animal covered in feathers, and was equipped with a small toothless beaked head, that may indicate an omnivorous diet.

## Description

Like other ornithomimids, *Ornithomimus* is characterized by a foot with three weight-bearing toes, long slender arms and a long neck with a birdlike, elongated, toothless, beaked skull. It was bipedal and superficially resembled an ostrich, except for its long tail. It would have been a swift runner. It had very long limbs, hollow bones, and a large brain and eyes. The brains of ornithomimids were large for dinosaurs, but this may not necessarily be a sign of greater intelligence; some paleontologists think that the enlarged portions of the brain were dedicated to kinesthetic coordination. Their hands are remarkably sloth-like in appearance, which led Henry Fairfield Osborn to suggest that they were used to hook branches during feeding. *Ornithomimus* differs from other ornithomimids, such as *Struthiomimus*, in having a short back, long slender forearms, very slender, straight hand and foot claws and in having metacarpals and fingers of similar lengths.

    The three *Ornithomimus* species today seen as possibly valid, differ rather in size. In 2010 Gregory S. Paul estimated the length of *O. edmontonicus* at 3.8 metres, its weight at 170 kilograms (370 lb). One of its specimens, CMN 12228, preserves a femur (thigh bone) 46.8 centimetres (18.4 in) long. O. sedens was by Paul estimated at 4.8 metres and 350 kilograms (770 lb). O. velox, the type species of *Ornithomimus*, is based on material of a much smaller animal. Whereas the holotype of *O. edmontonicus*, CMN 8632, preserves a second metacarpal eighty-four millimetres long, the same element with *O. velox* measures only fifty-three millimetres.

### Feathers

    In 1996, 2008 and 2009, three *Ornithomimus edmontonicus* specimens, two adults and a juvenile, were found with remains of pennaceous feather shafts on the lower arm or with impressions of up to five centimetres long primitive feathers in the form of hair-like filaments covering the rump, legs and neck. The fact that the feather imprints were found in sandstone, previously thought to not be able to support such impressions, gives new possibilities for future feather finds. A study describing these fossils in 2012 concluded that *O. edmontonicus* was covered in plumaceous feathers at all growth stages, and that only adults had pennaceous wing-like structures, suggesting that wings may have evolved for mating displays.

## JPInstitute.com Description

Ornithomimus sparked the first discussions in scientific circles that birds may have descended from dinosaurs. Its name even means that it looks like a bird.

A whole family of dinosaurs is named after Ornithomimus, including Struthiomimus and Gallimimus. They were all fast-running meat-eaters with small heads, long legs and long tails. Their heads were too small to eat larger creatures, so they probably ate a lot of small animals like lizards, insects, and small mammals.

Ornithomimus is a very well known and commonly found dinosaur. First discovered over 100 years ago, there are two and possibly four species assigned to this genus. There is evidence that this genus was one of the more evolutionarily advanced members of its family.

Much debate surrounds these creatures' diet. Their small heads don't seem very threatening compared to other theropods, and it has been variously suggested that they were herbivorous, omnivorous, primarily eaters of eggs and soft bodied creatures such as insects and lizards, and scavengers.

## Links

http://web.archive.org/web/20040420202717/http://www.jpinstitute.com/dinopedia/dinocards/dc\_ornit.html