220px-Utahraptor BW

Template:ItalictitleTemplate:Taxobox Utahraptor (meaning "Utah's predator")[1] is the largest known member of the theropod dinosaur family Dromaeosauridae, and dates from the upper Barremian stage of the early Cretaceous period (about 126 million years ago).[1]


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The holotype of Utahraptor is fragmentary, consisting of skull fragments, a tibia, claws and some caudal (tail) vertebra. The few elements suggest an animal about twice the size of Deinonychus.[1] Like other dromaeosaurids, Utahraptor had a huge curved claw on the second toe; one is preserved at Template:Convert in length and is thought to reach Template:Convert restored. The largest described specimens are estimated to have reached up to Template:Convert long and somewhat less than Template:Convert in weight, equivalent to the Grizzly bear in size.[1][2] Some undescribed specimens in the BYU collections may have reached up to Template:Convert long, though these await more detailed study.[3] It is thought that Utahraptor may be closely related to the smaller Dromaeosaurus and the giant Mongolian dromaeosaurid Achillobator.[1][4] Although feathers have never been found in association with Utahraptor, 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.[5] Since Microraptor 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 in dromaeosaurs, so assuming that Utahraptor lacked feathers would require positive evidence that it did not have them.[6] So far, there is nothing to suggest that feathers were lost in larger, more derived species of dromaeosaurs.[7]


James Kirkland, Robert Gaston, and Donald Burge discovered Utahraptor in 1991 in Grand County, Utah, within the Yellow Cat and Poison Strip members of the Cedar Mountain Formation.[1] Radiometric dating has shown that these parts of the Cedar Mountain Formation were deposited about 126 million years ago.[8] The type specimen is currently housed at the College of Eastern Utah Prehistoric Museum, although Brigham Young University currently houses the largest collection of Utahraptor fossils. The type species (and only known species of Utahraptor), Utahraptor ostrommaysorum, was named for the American paleontologist John Ostrom, from Yale University's Peabody Museum of Natural History, and Chris Mays, of Dinamation International. Sculptor Raymond Persinger was included in James Kirkland's original abstract referencing Mr. Persinger's concepts regarding the claw structure.

In popular cultureEdit

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A speculative reconstruction of Utahraptor lifestyles and behavior was presented in the 1999 BBC television series Walking with Dinosaurs.[9] The program portrayed Utahraptor with several anatomical inaccuracies including pronated hands, and depicted it living in Europe when the only fossils of Utahraptor have been found in western North America.[10] Ryan North's award-winning "Dinosaur Comics" online comic strip prominently features a Utahraptor. The Utahraptor character is meant to serve as a "questioning and interrogative" interlocutor in the comic's sometimes bizarre discussions of life and philosophy.[11]==References</ref>] </ref>==References ==References==

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Template:Cite journal
  2. Holtz, Thomas R. Jr. (2008) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages Supplementary Information
  3. Britt, Chure, Stadtman, Madsen, Scheetz and Burge, (2001). "New osteological data and the affinities of Utahraptor from the Cedar Mountain Fm. (Early Cretaceous) of Utah." Journal of Vertebrate Paleontology, 21(3): 36A.
  4. Template:Cite journal
  5. Xu, X., Zhou, Z., Wang, X., Kuang, X., Zhang, F. and Du, X. (2003). "Four-winged dinosaurs from China." Nature, 421(6921): 335-340, 23 Jan 2003.
  6. Prum, R. & Brush A.H. (2002). "The evolutionary origin and diversification of feathers". The Quarterly Review of Biology 77: 261–295. doi:10.1086/341993.
  7. Turner, A.H.; Makovicky, P.J.; Norell, M.A. (2007). "Feather quill knobs in the dinosaur Velociraptor". Science 317 (5845): 1721. doi:10.1126/science.1145076. PMID 17885130.
  8. Kirkland, J.I. and Madsen, S.K. 2007. The Lower Cretaceous Cedar Mountain Formation, eastern Utah: the view up an always interesting learning curve. Fieldtrip Guidebook, Geological Society of America, Rocky Mountain Section. 1-108 p.
  9. "Unnatural history? Deconstructing the Walking with Dinosaurs phenomenon." Media Culture & Society, 25(3): 315-332. Template:Doi
  10. Haines, T. (2000). Walking with Dinosaurs: A Natural History. London: BBC Publishing.
  11. Whaley, K. (2006). "Tall Poppy Interview: Ryan North of Dinosaur Comics." The Torontoist, 17 May 2006. accessed online 16 Sep 2010, [

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