Utahraptor (meaning "Utah's predator") is a genus of large dromaeosaurid (a group of feathered carnivorous theropods) dinosaur that lived during the Early Cretaceous period from around 135 to 130 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.

As a heavily built, ground-dwelling, bipedal carnivore, its large size and variety of unique features have earned it attention in both pop culture and the scientific community.

The jaws of Utahraptor were lined with small, serrated teeth that were used in conjunction with a large "killing claw" on its second toe to dispatch its prey.

Fossil remains of several individuals of various ages have been found together, suggesting that Utahraptor was gregarious (social) and practiced degrees of post nestling care.

The first specimens of Utahraptor were found in 1975 by Jim Jensen in the Dalton Wells Quarry of Utah, near the town of Moab, but did not receive much attention.

The specific name, ostrommaysi, is in honor to John Ostrom for his investigations on Deinonychus and its relationships to birds, as well as Chris Mays, who helped in the research of Utahraptor by founding Dinamation.

[2] Earlier, it had been intended to name the species "U. spielbergi" after film director Steven Spielberg, in exchange for him funding paleontological research, but no agreement could be reached on the amount of financial assistance.

[1] In the revised diagnosis conducted by Turner et al. in 2012, Utahraptor differs from other dromaeosaurids in having an elongate nasal process of the premaxilla, a distal end of metatarsal III that is smooth, not ginglymoid, an L-shaped quadratojugal without a posterior process, the presence of a well-developed notch between the lesser trochanter and greater trochanter, and dorsal vertebrae that lack pleurocoels.

[24] While dinosaur behavior can only be theorized, it was later discovered in 2020 that Deinonychus may not have practiced mammal-like pack hunting, based on differing dietary preferences in adults and juveniles.

According to the authors of its description, Utahraptor had an important ecological role as a major carnivore of the paleofauna of the present-day Arches region during the Early Cretaceous, and could probably attack prey larger than itself.

[27] Using advanced methods of radiometric and palynological dating, Joeckel et al. (2019) concluded that the Yellow Cat Member is indeed older than previous estimations.

[29] Utahraptor was unearthed from the Yellow Cat Member, which during the Berriasian to Late Valanginian was a semiarid area with floodplain prairies, riverine forests, and open woodlands predominated by conifers (Pinophyta), ferns (Polypodiopsida), hornworts (Anthocerotophyta) and other vascular plants.

This is supported by the presence of charred spores and other carbonized plant debris in the pollen maceral that indicate the occurrence of ancient wildfires ignited during periods of low precipitation.

[22][28] Paleofauna that were contemporaneous with the dromaeosaurid in the upper Yellow Cat Member included numerous dinosaurs, such as the medium-sized iguanodonts Hippodraco and Cedrorestes, the smaller theropods Martharaptor and Nedcolbertia, the nodosaurid Gastonia, and the sauropods Cedarosaurus and Moabosaurus.

[32] Other non-dinosaur or avian taxa known from the Member include the fish Ceratodus and Semionotus, the turtles Glyptops and Trinitichelys, Aquatilavipes (fossilized bird tracks), the rhynchocephalian Toxolophosaurus, and the indeterminate remains of hybodontid and polyacrodontid sharks.

[29] A neochoristodere unearthed from the Upper Yellow Cat Member, represented by a partial left femur,[33] shows that aquatic paleofauna was present and diverse during the Early Cretaceous of the Cedar Mountain Formation.

Written by paleontologist Robert T. Bakker, it was positively regarded by mainstream reviewers, though updates to the science have rendered some of the story line facts presented untrue and the paleontology community was critical of fossil record inaccuracies.

[38][39][40] In 2018, it was proposed by a 10-year-old elementary school student, Kenyon Roberts, that Utahraptor be the Utah state dinosaur, an act that was approved by the Senate.