yoo' - taw - rap" - tor
The utahraptor (thief from Utah) is a member of the dromaeosauridae (swift lizard) family, thought to be the smartest family of dinosaurs. A well-preserved skeleton was found in Gaston Quarry near Moab, Utah in the western United States in 1991, and it was named by paleontologists James Ian Kirkland, Robert Gaston and Donald Burge in 1993. The Gaston Quarry is extremely important in paleontology because a large number of new and poorly known dinosaur fossils have been found there, helping to fill in a 30 million year gap in what we know about North American dinosaurs. The utahraptor lived about 125 million years ago, in the early Cretaceous period, which indicates that members of the dromaeosauridea family got smaller as it evolved.
The utahraptor looked very similar to the famous velociraptor, except bigger. It was 2 meters (6 feet) tall and weighed nearly 1,000 kg (2,000 pounds). It was built for fast, agile bipedal running, with a long, thick tail used for balance both when running and also when attacking. And it must have been very good at attacking. It was covered in weapons, literally from head to toe. Its 500 cm (1.5 foot) skull was filled with 5 cm (2 inch) long, serrated teeth like steak knives. The claws on the end of its fingers were shaped like blades for slashing and holding. In addition, the large eyes would have given it keen eyesight to spot prey and its large brain cavity indicated that it was probably the smartest dinosaur of its time period.
But its main weapon was the sickle-shaped 20 cm (8 inch) long slashing claw on each foot. This claw was normally held extended up to avoid contact with the ground while running, which kept it sharp, and could be flexed downward by a large tendon in the foot for attacking. Estimates based on utahraptor's size indicate that it might have been able to make a nearly 2 meter slash with this claw in a devastating kick which would have been able to disembowel prey much larger than itself. It may have even used its hands to hold on to prey while delivering multiple kicks.
If the utahraptor was a pack hunter, roaming packs of these deadly carnivores would have been able to tackle pretty much any prey it wanted to, including sauropods. Although there is no direct evidence that they were pack hunters, they are closely related to deinonychus (based on special features found in the tail bones unique to dromaeosauridae), which probably was. One fossil find shows several deinonychus skeletons surrounding the skeleton of a plant-eater, which provides strong evidence to its hunting habits.
Interestingly enough, the discovery of this huge dromaeosaurid came right around the time dinosaur fans were complaining about the size of the velociraptors in the 1993 Steven Spielberg movie Jurassic Park. In order to make the stars of the movie scarier, they were increased from their real size of 1 meter tall to a more intimidating 2 meters, meaning the creatures called velociraptors in the movie were actually a fairly good representation of the utahraptor.