Utahraptor is an extinct genus of theropod dinosaurs. It lived during the Early Cretaceous epoch. Utahraptor ostrommaysorum, the type species, is the only recognized species belonging to this genus. It is the largest known member of family Dromaeosauridae. The name Utahraptor ostrommaysorum was given by Burge, Kirkland and Gaston in 1993.

Behavior

It is believed that Utahraptors stayed and hunted in packs. At times, they attacked their prey when they bogged down in thick mud or quicksand. In fact, they also attacked even large sauropods and ankylosaurids.

Physical appearance

Utahraptor’s holotype specimen is fragmentary. It only had skull fragments, claws, a tibia as well as some caudal (tail) vertebrae. Phylogenetic evidence suggested that they had feathers. Their bones were hollow, but strong. They had robust short legs that were primarily made for strength rather than speed. However, they are known to be a fast sprinter. They had large and sharp claws on their second toes.

Discovery

The exact range of this species is not known. The first fossil sample of this genus was found in 1975 by in Jensen in the Dalton Wells Quarry in Utah, near Moab town. It got much attention after a large foot-claw was found by Carl Limoni in October, 1991. In the same year, more skeleton remains were uncovered in Grand County, Utah. Radiometric dating showed that parts found in Cedar Mountain Formation were deposited around 124 million years ago. In the year 2001, Kirkland and others found a fossil block of sandstone in Utah carrying six individuals that includes one adult, four juveniles and one baby.

Interesting Facts

• The type specimen, named CEU 184v.86, is kept at College of Eastern Utah Prehistoric Museum. However, the largest collection of Utahraptor fossil samples is at Brigham Young University.
• Utahraptor ostrommaysorum was intended to be named “Utahraptor spielbergi”, after film director Steven Spielberg, in exchange of research fund for palaeontological studies. But, in the end, no agreement was reached.
• Since its discovery, Utahraptor has appeared in several films and documentary, such as ‘Walking with Dinosaurs’ produced by BBC.
• The Utahraptor type species – Utahraptor ostrommaysorum honors the well known American paleontologist John Ostrom and dinosaur robotics pioneer Chris Mays. Today, majority of paleontologists accept Ostrom’s theory that raptors like Deinonychus were distant ancestors of modern birds.
• Scientists believe that Dromaeosaurus and Achillobator were closely related to Utahraptor.
• Raptor Red, a novel by Robert T. Bakker, deals with the struggles of a female Utahraptor and her family.
• Utahraptor has the largest brain for any known dinosaur.