Ankylosaurus magniventris is the namesake and possibly the largest known member of the ankylosaurid family of dinosaurs, with a body mass of around four tons. A native of North America around 68 to 65 million years ago in the Late Cretaceous, the plant-eating Ankylosaurus would have been a contemporary of both the Triceratops and the Tyrannosaurus. Its spiky body armor and club-like tail would have provided it with natural protection against even the fiercest and hungriest tyrannosaur.