A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract and used to grind food in animals lacking suitable grinding teeth. Polished pebbles occasionally found within skeletons of giant herbivorous sauropod dinosaurs are very likely to be gastroliths.
The Utahraptor could grow up to 7 meters (20 feet) long and weigh almost a ton. A close relative of the Velociraptor, this dinosaur was a fierce predator. Like other dromaeosaurids, it had a huge, blade-like claw on its second toe. With this 20 centimeter talon, it is believed that the Utahraptor could make a deep cut 5 to 6 feet long with one swipe, enabling it to kill dinosaurs much larger than itself.
Although there have probably been dinosaur discoveries dating back thousands of years -- there are, for instance, references to "dragon bones" found in ancient China -- the first documented dinosaur discovery took place in 1676 when a jawbone and teeth were unearthed in Oxford, England. In 1824, famed paleontologist William Buckland (1784-1856) finally named this first dinosaur Megalosaurus. Megalosaurus was a large meat-eater that stood up to 9 meters (30 feet) tall and weighed about 1 ton.