Open Paleo

Utahraptor

Kirkland et al., 1993 YOO-tah-RAP-tor

Named for the state of Utah, USA, where the fossils were found, combined with Latin 'raptor' meaning 'robber' or 'plunderer'.

137.1–132.6 million years ago Valanginian, Early Cretaceous
Early Cretaceous stages

Utahraptor is a genus of large dromaeosaurid (a group of feathered carnivorous theropods) dinosaur that lived during the Early Cretaceous period from around 139 to 135 million years ago in what is now the United States. The genus was described in 1993 by American paleontologist James Kirkland and colleagues with the type species Utahraptor ostrommaysi, based on fossils that had been unearthed earlier from the Cedar Mountain Formation of Utah. Later, many additional specimens were described including those from the skull and postcranium in addition to those of younger individuals.

Diagnosis

  1. Manual claws more specialized as cutting blades than other dromaeosaurs, with H/W ratios 26-37
  2. Lachrymal with distinctly parallel mesial and outer sides, elongate subrectangular in dorsal view
  3. Premaxilla with base of nasal opening parallel to premaxillary tooth row
  4. Very large size, at least 100% larger than Deinonychus
  5. Manual claws more laterally compressed than pedal unguals

Species

Utahraptor ostrommaysi Kirkland et al., 1993

Type species

Named for paleontologist John Ostrom, for investigations on Deinonychus and its relationship to birds, and for Chris Mays, who helped fund research on Utahraptor through Dinamation.

Holotype
CEUM 184v.86 , College of Eastern Utah Prehistoric Museum
Material
Right second pedal ungual.
Notes
The associated first manus ungual, tibia, lachrymal, and premaxilla figured with the holotype are separately cataloged referred hypodigm elements, not part of the holotype.
Horizon
upper Yellow Cat Member, Cedar Mountain Formation, Valanginian, Early Cretaceous , 137.1–132.6 million years ago
Locality
Gaston Quarry, Utah, United States

Notable specimens

  • BYUVP 15465

    Earth Sciences Museum, Brigham Young University largest individual

    The largest specimen assigned to Utahraptor, with a femoral length of 56.5 to 60 cm, establishing the maximum known size of what is regarded as the largest dromaeosaurid; basis for body-length and mass estimates of the taxon.

    Kirkland et al. (1993)Molina-Pérez & Larramendi (2019)

References

  1. Molina-Pérez, R.; Larramendi, A. (2019). Dinosaur Facts and Figures: The Theropods and Other Dinosauriformes. Princeton University Press. molina-pérez2019a
  2. Kirkland, J. I.; Burge, D.; Gaston, R. (1993). A large dromaeosaur (Theropoda) from the Lower Cretaceous of eastern Utah. Hunteria 2(10): 1-16. kirkland1993a
  3. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the appearance features.

    paul2024a
  4. Kirkland, J. I.; Suarez, M.; Suarez, C.; Hunt-Foster, R. (2016). The Lower Cretaceous in east-central Utah — the Cedar Mountain Formation and its bounding strata. Geology of the Intermountain West 3: 101-228. Utah Geological Association. doi:10.31711/giw.v3.pp101-228

    Places the Gaston Quarry in the medial upper Yellow Cat Member, which the 1993 description predates by four years.

    kirkland2016a