Bones in the skull and other parts of the body were fused to increase their strength. Ankylosaurus did not share the grinding tooth batteries of the contemporaneous ceratopsid and hadrosaurid dinosaurs, indicating that very little chewing occurred. These teeth were smaller, relative to the body size, than in any other ankylosaurid species.

Like other ankylosaurs, Ankylosaurus was herbivorous, with small, leaf-shaped teeth suitable for cropping vegetation. The largest known skull measures 64.5 centimeters (25 in) long and 74.5 cm (29 in) wide. The skull was low and triangular in shape, wider than it was long. Although its feet are still unknown, comparisons with other ankylosaurids suggest Ankylosaurus probably had five toes on each foot. Ankylosaurus was quadrupedal, with the hind limbs longer than the forelimbs. The body shape was low-slung and quite wide. Ankylosaurus may have weighed over 6,000 kilograms (13,000 lb).

Another reconstruction suggests a significantly smaller size, at 6.25 m (20.5 ft) long, up to 1.5 m (5 ft) wide and about 1.7 m (5.5 ft) high at the hip. Some scientists have estimated a length of 9 meters (30 ft). Illustration of Ankylosaurus.In comparison with modern land animals the adult Ankylosaurus was very large.

Walking with dinosaurs ankylosaurus