ANKYLOSAURUS(ang-KYL-o-sawr-us) "Stiffened Lizard" (Greek ankylo = stiffen = sauros = lizard, because of its stiffened dermal armor) Sometimes mistakenly called EUOPLOCEPHALUS.

One of the largest and best known of the ANKYLOSAURS. The body, head, and TAIL of this "REPTILIAN tank" were covered with bony plates set close together in thick, leathery SKIN. A row of short SPIKES protected each side of the body. The TAIL was short and thick and ended in a bony club. This peaceful plant eater lived in western North America during the CRETACEOUS PERIOD. It was 25 feet (7.5 m) long, 6 feet (1.8 m) wide, and over 4 feet (1.2 m) tall. It weighed about 5 tons (4.5 metric tons). Ankylosaurus was one of the very last kind of dinosaurs to die out. It is known from fairly complete material found in Montana.

Ankylosaurus is sometimes called Euoplocephalus, but it is now believed that these were two different animals.

Classification: Ankylosauridae, Ankylosauria, Ornithischia