Temporal range: Early Cretaceous
|A restoration of Utahraptor ostrommaysorum|
Kirkland, Gaston & Burge, 1993
Kirkland, Gaston & Burge, 1993
Utahraptor (meaning "Utah thief") is extinct genus of carnivorous dromaeosaurid from the Barremian stage of the Early Cretaceous, living in what is now North America. Related to Deinonychus and Velociraptor, Utahraptor is the largest dromaeosaur known to science. Utahraptor is also a member of the Dromaeosaurinae, a group of dromaeosaurids that relied heavily on their jaws to kill their prey. Utahraptor was closely related to Dromaeosaurus, Achillobator, and Dakotaraptor among others based on cladistic analysis.
In 2018, it was proposed that Utahraptor be the Utah state dinosaur, an act that was approved by the Senate. Initially Utahraptor would have replaced another dinosaur, Allosaurus, as the state's official fossil, but it was decided that Utahraptor would be another symbol of the state.
Discovery and naming
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.
Utahraptor is a member of the family Dromaeosauridae, a clade of theropod dinosaurs commonly known as "raptors".
Utahraptor was a very large dromaeosaur, one of the biggest members of its' family. It was about 1.7-2 meters tall, 6-7 meters long, and weighed about 1,000 pounds/453 kg. It lived from 131 to 126 mya during the Barremian Stage of the early Cretaceous and is closely related to Achillobator and Dromaeosaurus. Its skeletal design was birdlike; with bones that were hollow, but strong. Recent fossil discoveries of more complete skeletons of Utahraptor by James Kirkland et al. paint a picture also of a dromaeosaur that was more heavily-built and stocky than the "typical" Deinonychus body plan generally associated with other dromaeosaurs. The legs were short and stocky, while the tail was also relatively short in comparison to that of related forms. The jaws were most unusual, with the front of the lower jaw bent forward and down in a case of convergence with the unrelated Masiakasaurus.
Utahraptor and other dromaeosaurs might have had binocular vision, like that of an eagle. Its hearing was probably excellent. Scientists recently discovered that raptors in general could best hear low f-equency sounds. Dromaeosaurs like Utahraptor, regardless of size, were all covered in feathers according to cladistic analysis. Though feathers from the arms were known to be true feathers in other dromaeosaurs such as Dakotaraptor and Velociraptor, the rest of the dinosaur's plumage is speculative (though fossil finds of smaller species exhibit many of the same types of feathers that are found in modern birds, In Utahraptor, the exact plumage type is not known).
The feathers on the arms of young dromaeosaurids would have enabled a special type of locomotion called wing-assisted incline running, or WAIR for short. Discovered by Ken Dial, a Montana zoologist, this is a behavior used by modern birds that combines flapping the wings back and forth while running up the sides of trees. This flapping pushes the feet of the bird against the tree, allowing it to run vertically up the trunk. This indicates, but does not prove, that small dromaeosaurs lived part-time in the trees. In larger species, the wing feathers may have helped to maintain balance while attacking prey.
Utahraptor’s diet consisted predominantly of large herbivorous dinosaurs. In the formations where it was found (the Yellow Cat and Poison Strip members of the Cedar Mountain Formation, respectively), Utahraptor lived alongside such dinosaurs that it preys on such as Gastonia, Iguanodon, Hippodraco, Cedrorestes, Iguanacolossus, Martharaptor, and Falcarius. Sauropods such as Venenosaurus and Cedarosaurus were also on its menu and also found here, as were other predators that it live with such as Nedcolbertia and Geminiraptor. Any one of these was a potential prey item, though the smaller animals such as Necolbertia would have been little in the way of a meal for such a predator as Utahraptor. As with all predators, Utahraptor likely targeted animals such as the infirm, weak and inexperienced. Scavenging was also probably a preferable opportunity when there was access to a carcass. Like most dromaeosaurine dromaeosaurids, Utahraptor probably relied on its jaws to kill prey more than other subfamilies of dromaeosaurs did. As a result and based on the analysis of related species like Dromaeosaurus, which included bone in its diet, Utahraptor probably had an extremely powerful bite as a result.
Speed and Agility
Utahraptor was likely an ambush predator. Given its robust, stocky build and short legs, it was not particularly fast, but given that its prey was likely slower, what it lacked in speed it made up for with power and agility.
Utahraptor's habitat was a series of floodplains and open woodlands with riverine forests. The wet season was short in this habitat and the climate was semi-arid. As Utahraptor was not fast, it likely used the available cover to lie and wait for prey.
In 2001, Kirkland et al, pursued a graduate student's discovery of a bone protruding from a 9-ton fossil block of sandstone in eastern Utah. It was determined to contain the bones of at least seven individuals, including an adult measuring about 4.8 meters, four juveniles and a hatchling about 1 meters long. Also fossilized with the predators are the remains of at least one possible iguanodont herbivore. Kirkland speculated that the Utahraptor pack attempted to scavenge carrion or attack helpless prey mired in quicksand, and were themselves mired in the attempt to attack the herbivore. Similar sites such as the Cleveland-Lloyd Quarry and California's La Brea Tar Pits house such predator traps. Examination of the fossils are ongoing after a decade of excavation, but if Kirkland is correct, it may be one of the best-preserved predator traps ever discovered. The fossils may further reveal aspects into the behavior of Utahraptor, such as whether it might have hunted in groups like Deinonychus was believed to have done. Whether all the Utahraptor individuals were mired simultaneously or were drawn in, one-by-one is unclear. Further examination of the block suggests that the number of Utahraptor remains maybe double the amount previously assumed.
While the social and complex behavior of the dromaesauridae can merely be theorized, it was later discovered in 2020 that Deinonychus may not have had complex social behavior seen in some pack-hunting animals in the modern era.
In the Media
- Utahraptor appears in the Walking with Dinosaurs series shown hunting a herd of the herbivore Iguanodon. It lacks feathers, is shown inaccurately with pronated hands, and most inaccurately of all, is shown living in Europe.
- A Utahraptor appears in Jurassic Fight Club fighting a Gastonia. (In a drought.)
- It also appears in the popular PC game Zoo Tycoon 2 where it is inaccurately oversized.
- In Primeval Series 1, Ep 4, Helen Cutter mentions meeting a Utahraptor in the Jurassic, but in reality, the dinosaur is actually from the Cretaceous. A Utahraptor is set to appear in Primeval: New World, where it fights a Pteranodon.
- An accurate version of Utahraptor appears in Dinosaur Revolution, and its film version, Dinotasia as a predator of Cedarosaurus.
- The novel Raptor Red focuses on a female Utahraptor named Red.
- A pair of Utahraptors appeared in an Animated Dinosaur Documentary while hunting an Iguanadont Dinosaur. “Only a couple stock footages of the Animated Documentary they came from what was seen in Really Wild Animals: Dinosaurs & other Creature Features. The real Documentary is a mystery. Probably from Dinosaurs on Earth, Then... and Now by the National Geographic Society.”
- Two panels of each Dinosaur Comics features a Utahraptor.
There is a purple "Utahraptor" with yellow quills in Dinosaur King.
- Utahraptor can be created in Jurassic Park: Builder. At first, it could only in the Jurassic card packs purchasable by real money. Since February 12th 2016, it became a DNA tournament limited edition. Unlike most dromaeosaurids in the Jurassic Park franchise, this depiction of Utahraptor has fur-like feathers all over its body and even wings, although it is shown inaccurately to be able to pronate its hands.
- Utahraptor can be created in Jurassic World: The Game. Unlike most dromaeosaurids in the Jurassic Park franchise, this depiction of Utahraptor has fur-like feathers all over its body and even wings, although it is shown inaccurately to be able to pronate it's hands in battle.
- The ARK: Survival Evolved Raptor is a fictional species of Utahraptor. It is inaccurately mainly scaly with only a small amount of feathers on parts of the body. They also are inaccurately able to pronate their hands.
- Utahraptor will be Jurassic World: Alive. Unlike most dromaeosaurids in the Jurassic Park franchise, this depiction of Utahraptor has fur-like feathers all over its body and even wings, although it is shown inaccurately to be able to pronate it's hands.
- The Utahraptor appears as an anthromorphic creature in the Battlesaurs group in Toy Story That Time Forgot.
- Utahraptor appears in the adult science-fiction novel Primitive War and its spin-offs written by Ethan Pettus. In this novel, Utahraptor serves as the primary dinosaur antagonist, and they are depicted as being intelligent, having green, brown, and black feathers to blend in with the undergrowth, and can camouflage themselves as bushes and trees to sneak up on their prey before killing it in a gruesome fashion by eviscerating them. These and many other dinosaurs appear in the human era in Vietnam after a Soviet device called the "Collider" accidentally opens wormholes into multiple time periods, bringing forth a huge pack of Utahraptors to the years of the Vietnam War. The Utahraptors ultimately begin replacing the native predators in the valley surrounding the Soviet base, as well as developing a taste for human flesh. Throughout the novel, they pursue the main characters, the soldiers of Vulture Squad, and manage to wound or kill three members of the unit as well as most of the main human antagonists. Eventually, after the Collider is destroyed, the remaining members of Vulture Squadron, reformed into Stalker Squadron, begin to hunt the Utahraptors, only to have them escape the fenced-off valley created by the U.S. Military that keeps the dinosaurs contained.
- A bunch are seen in Inspector Gadget.