Ankylosaurus is a familiar animal, often purported in popular culture, needless to say inaccurately. It was one of last genera of non-avian dinosaurs to have existed, & would've lived alongside the Tyrannosaurus. This is not to say, however, that Ankylosaurus was prey to large animals; it was coated in bony armor unlike a turtle's shell, more akin to a crocodile.
Two chunks of bone on the end of tail acted as active defense, similar to Stegosaurus' tail spikes, only this 'club' would have broken bones instead of piercing flesh. Ankylosaurus has often been likened to a living tank, supported by experiments that show Ankylosaur's armor was bullet-proof, & at least one genus' armor was constructed in a very similar fashion to modern-day bullet-proof vests.
Consequentially their legs were strong & dense. Ankylosaurus was a Thyreopean, like Stegosaurus, & ate low-lying vegetation. It has not been found with gizzard stones, suggesting its jaw was powerful enough to break up plants, & it probably possessed more than one stomach, like a modern day cow.