Utahraptor ostrommaysorum was a bipedal predator that haunted the land that became the United States of America during the early Cretaceous, 126 million years ago. The name of the animal means “Utah’s thief”, referring to the state where the first fossils were unearthed in 1993.

The Paleontologists

The specific name of this dinosaur is a tribute to the famous paleontologists John Ostrom and Chris Mays. Originally the name proposed was spielbergi, after director Steven Spielberg, in exchange for palaeontological research funds but an agreement was never reached.

Predators with feathers

This animal was a large dromaeosaurid theropod that reached 7 meters in length and 500 kgs of weight. Unlike the popular depictions of “raptors”, fast and highly intelligent reptile-like dinosaurs, these animals were feathered ambush predators.


Did you know that Utahraptor had a 26 centimeters long “sickle claws” on each foot? It used these claws to get a grip on its prey while maintaining balance with its wings and biting the victim with its jaws. U.ostrommaysorum probably hunted large dinosaurs around at the time. These included the armoured Gastonia, the sauropod Cedarosaurus and the iguanodontian Cedrorestes.

New discoveries

The information on this dinosaur is constantly updating because new digsites are always bringing new fossils that consistently change the image of this animal. The new discoveries give us a different animal than initially thought: from a light and agile animal to a bulkier one with a shorter but more mobile tail, a shorter torso and powerful legs.

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