Ornitholestes

Skeleton in the American Museum of Natural History

• North America, Morrison Formation

Ornitholestes is a theropod dinosaur from the group of Coelurosauria. It was a small, bipeder carnivores, whose remains in the layers of the Morrison Formation (late Jurassic) were found in the territory of the Northwestern United States. The only genus of this species is attributed Ornitholestes hermanni. Ornitholestes is one of the popular smaller dinosaurs.

Features

Ornitholestes was about two meters long and 15 to 20 kilograms, with the tail accounting for about half the body length. Compared to the related Coelurus he has a rather short neck and body. The lower leg bones are abnormally short - probably he was therefore not such a fast runner like other similar theropods.

The skull is compared with other theropod of its size, quite small and compact. Very often Ornitholestes was presented with a small, leaf -shaped comb or a horn above the nostrils. Recent studies, however, have refuted such a headdress: After the skull was once again prepared thoroughly, it has been discovered that it is slightly pushed in, causing the left Nasalknochen had moved and was misinterpreted as a headdress.

A special feature that Ornitholestes with Proceratosaurus divides, is the Heterodontie: The teeth of the front half of the jaw are much smaller and conical shaped as that of the rear half of the jaw.

Finds and Fund History

The holotype material (AMNH 619) is a partial skeleton, which among other things, a fairly complete skull, the majority of the vertebrae, pelvic bones, an incomplete femur (femur ), a part of the fibula ( fibula ), different toe bones ( metacarpals ), two upper arm bone (humerus ), and various fragments is. Recent finds from Wyoming could also be attributed to the Ornitholestes.

Previously isolated held one hand bones discovered also the Ornitholestes for belonging ( Osborn, 1916). Carpenter and others wrote this hand 2005, however, due to large similarities Tanycolagreus, another small carnivores of the Morrison Formation, too.

The skeleton was in the " Bone Cabin Quarry ", 13 kilometers north of Como Bluff, discovered. Como Bluff, a dinosaur cemetery of the Morrison Formation, is one of the most important sites for dinosaurs - here also the Related Ornitholestes Coelurus was discovered ( Marsh, 1879). Ornitholestes was named by Henry Fairfield Osborn in a brief description in 1903, in 1916 was followed by a more extensive description. Osborn chose the name Ornitholestes, which means " bird robber " because he imagined an active, fast hunters.

1920 Ornitholestes was then attributed by the Gilmore Coelurus, as the vortex of the two species have the researcher 's view, only minimal differences. Only in 1980 was recognized the various differences between the two species ( Ostrom, 1980), and Ornitholestes was again as a separate genus.

In the year 2005 a new description of Coelurus and Ornitholestes.