Ankylosaurus is a genus of ankylosaurid dinosaur. Fossils of Ankylosaurus are found in geologic formations dating to the very end of the Cretaceous Period (between about 68–66 million years ago) in western North America. This particular Ankylosaurus is showcased in the Walt Disney feature film Dinosaur.
Ankylosaurus was a large animal by modern standards. The largest known skull measures 64.5 cm (25.4 inches) long and 74.5 cm (29.3 inches) wide. Based on this skull, and using the body proportions of smaller specimens, the largest specimen has been estimated to be 6.25 m (20.5 feet) long, 1.5 m (4.9 feet) wide, and 1.7 m (5.6 feet) tall at the hip.
The body shape was low-slung and quite wide. It was quadrupedal, with the hind limbs longer than the forelimbs. Although its feet are still unknown, comparisons with other ankylosaurs suggest Ankylosaurus probably had five toes on each foot. The skull was low and triangular in shape, wider than it was long. Like other ankylosaurs, Ankylosaurus had small, leaf-shaped teeth, which were the smallest relative to the body size, than in any other ankylosaurid species, and lacked the tooth batteries of the contemporaneous ceratopsid and hadrosaurid dinosaurs. Bones in the skull and other parts of the body were fused, increasing their strength.
