About Utahraptor
| Scientific Name (Genus) | Utahraptor |
| Meaning of Name |
Utah thief
Utah [place name] - raptor (thief) [Latin] |
| Classification | Saurischia, Theropoda, Dromaeosauridae |
| Total Length | Approx. 6 - 7m |
| Diet | Carnivorous |
| Period | Early Cretaceous (approx. 139 - 135 million years ago) |
| Sub-classification / Species Name | Utahraptor ostrommaysi |
| Year of Paper Publication | 1993 |
| Genus Name Publication |
A large dromaeosaur [Theropoda] from the Lower Cretaceous of Utah.
Hunteria. 2. by Kirkland, J.I.; Burge, D.; Gaston, R. 1993. |
Utahraptor: Features and Latest Appearance
Utahraptor is one of the largest carnivorous dinosaurs of the Dromaeosauridae family, living in North America during the Early Cretaceous (about 139 to 135 million years ago). Previously thought to have lived about 125 million years ago, recent geological dating has revealed that it lived more than 10 million years earlier.
Utahraptor differed from its smaller, delicately built, and agile relatives. Its skeleton was robust, especially its short, stout hind legs. With a total length of about 6 to 7 meters and an estimated weight of up to 777 kg, it is thought to have had a massive body and overwhelming muscle strength comparable to a modern polar bear.
Additionally, since many feathered fossils have been found among the Dromaeosauridae family, it is highly likely that Utahraptor was also fully covered in feathers.
Formidable Hunting Tactics
The second toe of Utahraptor's hind legs developed a giant sickle-shaped claw that was about 24 cm long just in the bone core. For a long time, this giant claw was thought to be a weapon for "slashing" the flesh of prey.
However, in recent years, this hypothesis has been rejected.
Recent biomechanical research has shown that the inside of the claw lacked a sharp edge, making it unsuitable for slashing. It is now believed that, like modern hawks and eagles, it was used to pierce deeply into prey and "pin it down (restrain it)".
A hunting hypothesis in which, like birds of prey when hunting, it jumps and clings to prey with sharp claws, using its own weight and grip strength to pin the prey to the ground and restrain it.
Furthermore, it has been revealed that the front claws, which were previously confused with the hind claws in reconstructions, were shaped like extremely curved "meat hooks." Utahraptor likely jumped onto herbivorous dinosaurs as large as or larger than itself, clinging with its hind claws while embracing the prey with its sharp front claws, delivering a fatal blow with its powerful jaws.
A behavior in birds where flapping their wings while climbing steep slopes generates aerodynamic downward force (traction) to increase foot grip. It is thought that Utahraptor, when jumping on struggling prey, furiously flapped its feathered, giant forelimbs (wings) to maintain balance and avoid being thrown off.
Dinosaur Quicksand Hell: A 9-Ton Fossil Block
The possibility that Utahraptor hunted in packs was supported by a massive 9-ton block of fossils discovered in Utah.
Inside this rock mass, which is thought to have once been quicksand (a mud trap), dozens of Utahraptors of various ages, including 1 adult, 10 juveniles (subadults), and 3 babies, were entombed along with their prey, an iguanodontian herbivorous dinosaur (such as Hippodraco).
Researchers outline a scenario: "First, a herbivorous dinosaur got stuck in the mud, and a pack of Utahraptors that spotted it attacked, but they too lost their footing in the mud one after another and were buried alive." This discovery suggested that Utahraptors acted in packs and possessed social behavior, cooperating to hunt prey larger than themselves.
Discovery and Description
The first fossils were discovered in 1975 at the Dalton Wells Quarry in eastern Utah, USA, but they did not attract attention at the time. Later, in 1991, the discovery of a characteristic large foot claw at the Gaston Quarry in Utah brought it into the spotlight, and it was described as a new genus and species by paleontologist James Kirkland and others in 1993.
There is a famous anecdote regarding the description of the species. At the time, the right to name the species was offered for sale in exchange for funding the research, and a proposal was made by film director Steven Spielberg, famous for the movie "Jurassic Park," to make the type species name "Utahraptor spielbergi." However, the funding amount did not reach an agreement, and the director's name was not adopted.
Ultimately, the species name ostrommaysi was adopted, derived from paleontologist John Ostrom, who proposed the phylogenetic link between birds and theropods, and Chris Mays, the founder of an animatronics company.
After naming, since it was derived from two people's names, there was a proposal to correct it to "ostrommaysorum" according to Latin grammar rules, and it was written that way for a long time. In recent years, however, strict application of the International Code of Zoological Nomenclature found no error in the original description of "ostrommaysi," and the original name has returned to being used as the valid name.
Utahraptor Stamp and Fossil Gallery
