4.4" Fossil Dinosaur (Ankylosaurus) Scute - South Dakota

Ankylosaurus was the namesake of the Ankylosaurid family of dinosaurs to which it belonged, and one of the last ones to live before the Cretaceous-Paleogene extinction event 65 million years ago. Residing in western North America, Ankylosaurus was an herbivorous dinosaur with a low, squat body, a short neck with a square head, and a long tail ending with a large, bony club which it likely used for self-defense against predators like T.rex. Perhaps most notably, Ankylosaurus was one of the most heavily armored dinosaurs of all time. Ankylosaurs were known for their heavy bone armor all over the top half of their bodies, as well as bony knobs protruding all over their backs and face. Even their eyelids were protected against potential attack.

At adult size, these impenetrable behemoths measured about 25-30 feet and 4 to 8 tons. At that size, even an adult Tyrannosaurus would have had difficulty getting close enough to try and flip it to get at Ankylosaurus's less armored underbelly. Dinosaurs like Ankylosaurus prove indubitably that herbivores were just as impressive and dangerous as their carnivorous counterparts.

Because of its age and sedimentary composition, the Hell Creek Formation has become one of the most paleontologically studied areas in the world. 158 genera of animals and 64 genera of plants are known from the formation and new discoveries are made frequently. In addition to Tyrannosaurs, Ceratopsids, and Hadrosaurs, the formation has yielded remains of amphibians, reptiles, lizards, snakes and turtles, fish and sharks, avian and non-avian dinosaurs, and mammals. The Hell Creek Formation gives the most complete understanding of the environment just before the Cretaceous-Paleogene extinction.