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Last updated on April 18, 2014 at 17:24 EDT

Utahraptor

Utahraptor, meaning “Utah’s predator,” is a genus of theropod dinosaur from the upper Barremian stage of the early Cretaceous Period (approximately 126 million years ago). Utahraptor was discovered by James Kirkland, Robert Gaston, and Donald Burge in 1991 in Grand County, Utah, within the Yellow Cat and Poison Strip region of the Cedar Mountain Formation.

The type specimen, and only known species, U. ostrommaysorum, is housed at the College of Eastern Utah Prehistoric Museum. However, Brigham Young University houses the largest collection of Utahraptor fossils. The type species was named for American paleontologist John Ostrom, who worked for Yale University’s Peabody Museum of Natural History, and also for Chris Mays, of Dinamation International.

The holotype of Utahraptor is fragmentary at best, consisting of various skull fragments: a tibia, claws, and some tail vertebra. Based on the few fragments, it is suggested the animal is about twice the size of Deinonychus.

Like other dromaeosaurids, Utahraptor had a huge curved claw on the second toe. One is preserved at 8.7 inches long and is thought to reach up to 9.4 inches long. The largest described specimens are about 23 feet long and weigh less than 1,100 pounds. Although, some undescribed specimens at BYU may have reached up to 36 feet long.

It has been suggested that Utahraptor may be closely related to the smaller Dromaeosaurus and the giant Mongolian dromaeosaurid Achillobator.

Although feathers have never been found with Utahraptor, there is strong phylogenic evidence that all dromaeosaurids possessed them. This evidence comes from phylogenic bracketing, which allows paleontologists to infer traits that exist in a clade based on the existence of that trait in a more primitive form.

The genus Microraptor is one of the oldest known dromaeosaurids, and is phylogenetically more primitive than Utahraptor. Since Microraptor possessed feathers, it is reasonable to assume that this trait was present in all Dromaeosaurids. Feathers were very unlikely to have evolved more than once in dromaeosaurs, so assuming Utahraptor lacked feathers would require positive evidence that it did not have them.

The novel “˜Raptor Red,’ by Robert Bakker, tells the story of a Utahraptor from the perspective of the creature. Utahraptor has also been popularized in the BBC television series “˜Walking with Dinosaurs’ and the History series “˜Jurassic Fight Club.’ Both series portrayed Utahraptor as nearly completely featherless (apart from a small crest of feather spikes on their heads). The BBC feature also featured the Utahraptor as living in Europe when the only fossils found came from America. Although, at the time when Utahraptor lived, North America and Europe were joined together.

Utahraptor has also been portrayed in the web-comic Dinosaur Comics, and also has appeared as villainous in “˜The Land Before Time XI: Invasion of the Tinysauruses’. The Paul Zindel novel “˜Raptor’ features an evolved species of featherless Utahraptor living in a system of caves in present-day Utah.

Utahraptor