Ornithomimus
| Ornithomimus | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Ornithomimus fossil |
||||||||||||
| Temporal occurrence | ||||||||||||
| Upper Cretaceous ( Maastrichtian ) | ||||||||||||
| 72 to 66 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Ornithomimus | ||||||||||||
| Marsh , 1890 |
Ornithomimus was a genus of dinosaurs from the group of Ornithomimosauria within the Theropoda . He lived in the late Upper Cretaceous in what is now North America. Dromiceiomimus is mostly considered the same genus today.
features
Ornithomimus had the build typical of all Ornithomimidae . It was a slender dinosaur with a relatively small head sitting on a long neck. He only moved biped (on his hind legs). Its total length was around 3 to 4 meters.
The snout was elongated and ended in a horned beak, teeth were absent. The head was lightly built and partially pneumatized (that is, provided with air-filled cavities), the eyes were large and sat on the side of the head. The forelimbs were relatively large, but weakly built. The hands carried three fingers that ended in blunt claws. An autapomorphism of this type is that the first metacarpal is longer than the other two. The hind legs were long, the lower legs longer than the thighs, which suggests that Ornithomimus was a fast runner. The metatarsal bones were elongated, the feet ended in three forward-facing toes.
Due to the modified hind legs, Ornithomimus is considered a fast runner, possibly reaching speeds over 60 km / h. What it ate with its toothless beak is not known. Finds of gastroliths in other ornithomimosaurs could speak for a plant-based diet. Small invertebrates as prey or an omnivorous diet are also conceivable.
Fossils of a young animal and two adult specimens from Alberta , around 72 million years old, show that ornithomimus had downy feathering and that the older ones also had longer feathers on their forearms that gave their forelegs an appearance similar to that of a bird's wing. The late development of the long forearm fletching suggests that it may have served as a means of showing off or offered additional protection for the eggs of breeding animals.
Systematics
Ornithomimus was the first known representative of the Ornithomimidae and the Ornithomimosauria, its fossils were found in western North America . The first known species was velox Ornithomimus by Othniel Charles Marsh in 1890 described . The remains of this species are poor, the second species, Ornithomimus edmontonicus , described by Charles Mortram Sternberg in 1933 , is much better preserved . Some other species are either considered synonyms of these two species or have been classified in their own genera, such as Archaeornithomimus . The name Ornithomimus means ("bird imitator") and alludes to the similarity with ratites .
Finds of this genus come from the US states of Colorado , Utah and Wyoming as well as from the Horseshoe Canyon Formation in the Canadian province of Alberta . The finds are dated in the Upper Cretaceous ( Maastrichtian ) to an age of about 72 to 66 million years.
In 1972, several individuals were classified into a new genus Dromiceiomimus ("emu imitators") based on differences in skeletal proportions and two species were described with D. brevitertius and D. samueli . Later investigations with a wider range of fossils could not confirm this separation, the animals are all classified in the species Ornithomimus edmontonicus today .
literature
- Peter J. Makovicky , Yoshitsugu Kobayashi, Philip J. Currie : Ornithomimosauria. In: David B. Weishampel , Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 137-150.
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 114, online .
- ↑ Darla K. Zelenitsky, François Therrien, Gregory M. Erickson, Christopher L. DeBuhr, Yoshitsugu Kobayashi, David A. Eberth, Frank Hadfield. Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins. In: Science . Vol. 338, No. 6106, 2012, pp. 510-514, doi : 10.1126 / science.1225376 .
