Ankylosaurus is a very famous armored dinosaur. All other armored dinosaurs belong to the class Ankylosauria, which gets its name from this dinosaur.
Ankylosaurus was one of the last armored dinosaurs to live, and indeed one of the last dinosaurs of any type to live.
During the time period that Ankylosaurus roamed the North American continent, a number of large, dangerous predators were also on the prowl, including Tyrannosaurus. Ankylosaurus was a slow moving herbivore and needed protection from these hungry hunters.
This protection came in the form of sharp spikes, and a long heavy hammer tail that could be used to break the legs of its enemies. Even the eyelids of Ankylosaurus were plated for protection.
Ankylosaurus was nearly 2.5 meters (8ft) wide and 10 meters (33ft) long. Yet it only stood about 1-2 meters (3-6.5ft) off the ground.