|Scientific name :||Utahraptor ostrommaysi"|
|Time period :||Early Cretaceous|
|Primary diet :||Carnivore|
|In the series|
|Fatalities caused :||None|
|Appearances :||Survival Tactics|
Utahraptor ("Theif from Utah") was a carnivorous theropod dinosaur and probably a swift moving animal that lived in the Early Cretaceous (126 million years ago) and was the largest Dromeaosaur of the maniraptoran dinosaur group and weighed about half a tonne with a big killing claw, it also had feathers like birds do. Contrary to popular belief, there is very little evidence of coordinated pack hunting, with raptors more likely forming loose mobs, although Utahraptor may have not even done this.
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 (4 brown and 5 grey) were after the same young Cedarosaurus in a herd. The grey pack got to it first but the brown ones fought with them. In the clash, one of the brown members right eye was stabbed by a grey member's killing claw and another brown member is killed by a grey member's killing claw to the chest. They continued wounding each other until 3 members of each pack were left (the brown leader only appeared when it attacked the grey leader and later with a grey member). The young sauropod tried to escape while they were fighting but a crocodyloform grabbed it's back leg and attempted to drag the young sauropod into the water. The Utahraptors were alerted to this by the young sauropod's cries and, both sides now focusing on trying to secure the kill together, raced into action and forced the croc away (the grey leader having 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, killing it on impact, and one knocked the leader of the grey pack into the lake. The young was now with the herd and only one of each member of the pack (grey member and brown leader) survived and teamed up as they retreated. At the end the grey leader was swimming up to the surface but the crocodyloform from before grabbed it and killed it, as revenge for stabbing it's eye out.
- Originally one of the scientific names were Utahraptor spielbergi, but it was not selected.
- As of the latest scientific finding, Utahraptor has received a drastic make over, being much stockier than previously believed. As a result, pack hunting, and even group living is much less likely.
- Utahraptor was one of the largest theropods in the cedar mountain formation.
- Aside from being the largest raptor it was likley one of the oldest from the early Cretaceous.
- Being so heavy utahraptor could only run at 20 kph although still faster than most humans.
- In the episode, the brown leader has a brown smudge on it's face and the grey leader has a 'beard'.