|Scientific name :||Utahraptor ostrommaysorum|
|Time period :||Early Cretaceous|
|Primary diet :||Carnivore|
|In the series|
|Appearances :||Survival Tactics|
Physical Characteristic Edit
The holotype specimen of Utahraptor is fragmentary, consisting of skull fragments, a tibia, claws and some caudal (tail) vertebrae. These few elements suggest an animal about twice the length of Deinonychus. Like other dromaeosaurids, Utahraptor had large curved claws on their second toes. One claw specimen is preserved at 22 centimetres (8.7 in) in length and is thought to reach 24 centimetres (9.4 in) restored.
The largest described U. ostrommaysorum specimens are estimated to have reached up to 7 m (23 ft) long and somewhat less than 500 kg (1,100 lb) in weight, comparable to a polar bear in size.
It is thought that Utahraptor may be closely related to the smaller Dromaeosaurus and the giant Mongolian dromaeosaurid genus Achillobator.
Although feathers have never been found in association with Utahraptor specimens, there is strong phylogenetic evidence suggesting that all dromaeosaurids possessed them. This evidence comes from phylogenetic bracketing, which allows paleontologists to infer traits that exist in a clade based on the existence of that trait in a more basal form. The genus Microraptor is one of the oldest known dromaeosaurids, and is phylogenetically more primitive than Utahraptor. Since Microraptor and other dromaeosaurids possessed feathers, it is reasonable to assume that this trait was present in all of Dromaeosauridae. Feathers were very unlikely to have evolved more than once, so assuming that any given dromaeosaurid, such as Utahraptor, lacked feathers would require positive evidence that they did not have them. So far, there is nothing to suggest that feathers were lost in larger, more derived species of dromaeosaurs.
In a 2001 study conducted by Bruce Rothschild and other paleontologists, two foot bones referred to Utahraptor were examined for signs of stress fracture, but none were found.
The first specimens of Utahraptor were found in 1975 by Jim Jensen in the Dalton Wells Quarry in east-central Utah, near the town of Moab, but did not receive much attention. After a find of a large foot-claw by Carl Limoni in October 1991 James Kirkland, Robert Gaston, and Donald Burge uncovered further remains of Utahraptor in 1991 in the Gaston Quarry in Grand County, Utah, within the Yellow Cat and Poison Strip members of the Cedar Mountain Formation. Radiometric dating has shown that these parts of the Cedar Mountain Formation were deposited about 124 million years ago. The type specimen, CEU 184v.86, is currently housed at the College of Eastern Utah Prehistoric Museum, although Brigham Young University, the depository of Jensen's finds, currently houses the largest collection of Utahraptor fossils.
The type species (and only known species of Utahraptor), Utahraptor ostrommaysorum, was named by Kirkland, Gaston, and Burge in 1993 for the American paleontologist John Ostrom from Yale University's Peabody Museum of Natural History, and Chris Mays of Dinamation International. Originally, in the specific name, the singular genitive ostrommaysiwas used but, in 2000, this was emended by George Olshevsky to the plural. Earlier, it had been intended to name the species "Utahraptor spielbergi", after film director Steven Spielberg, in exchange for funding palaeontological research, but no agreement could be reached on the amount of financial assistance.
It appeared in the third episode where 2 packs (brown and grey) were after the same young Cedarosaurus in a herd. The grey pack got to it first but the brown ones fought with them. They wounded each other until 2 members of each pack were left. The young tried to escape while they were fighting but a crocodilyform grabbed it's back leg and the Utahraptors saw this and raced into action and forced the croc away (one stabbed its eye with the killing claw). As they were about to kill the young sauropod, the adults arrived and one kicked a brown one and killed it and one knocked a grey one into the lake. The young was now with the herd and only one of each member of the pack survived as they retreated. At the end the grey one was swimming up to the surface but the crocodilyform from before grabbed it and killed it.
- Originally one of the scientific names were Utahraptor spielbergi, but it was not selected.
- Some unpublished material might mean a new look for Utahraptor.