Utah Dinosaur 'death trap' reveals tove of predators

A nine-ton block of sandstone that was pulled from a Utah mountain in 2014 holds the biggest fossil trove ever found of the giant predatory dinosaur known as Utahraptor. Utahraptor was covered in feathers, with a huge sickle claw on each second toe. All the Utahraptor fossils are contained within a large block of sandstone that was once what geologists call a "dewatering feature," or quicksand. The Utahraptor was the largest of a group of lightly-built carnivores, called the dromaeosaurs ('swift lizards'). It had large eyes, long grasping hands and powerfully clawed feet.

It was carnivorous and relied on a hooked, slashing claw on each foot rather than the jaws and teeth of a typical predator. Its toe joints were specially enlarged so that its massive claw could be raised upward and backward to avoid damage while running.

The dromaeosaur group also included Velociraptor, made famous by Steven Spielberg in 'Jurassic Park'.

By chipping off smaller pieces of the block, researchers uncovered bones from a 16-foot-long adult Utahraptor, four juveniles, and a baby that would have been only about three feet long.

Other bones at the site belong to a beaked, bipedal herbivore called an iguanodont. The dinosaurs may have been what attracted the Utahraptor group to the site.