Dinosaurs / Cretaceous / Ankylosaurus
Ankylosaurus
Cretaceous ang-KYE-loh-SAWR-us, “fused lizard”
Ankylosaurus is among the most famous armoured dinosaurs and one of the last non-avian dinosaurs to evolve before the Cretaceous-Paleogene extinction. Inhabiting western North America alongside Tyrannosaurus and Triceratops, this enormous quadruped reached lengths of up to eight metres and weighed as much as an elephant. Despite its fame, a fully complete skeleton has never been unearthed, so much of its reconstruction is inferred from close relatives. Its body was encrusted with bony plates called osteoderms embedded in thick skin, while its broad skull sported backward-pointing triangular horns. At the tip of its stiffened tail sat an imposing bony club capable of shattering the legs of large attacking predators. It grazed low-lying vegetation using small, leaf-shaped teeth and an expansive, fermenting digestive gut.
Its massive tail club was composed of modified dermal osteoderms fused tightly around the terminal vertebrae.
Where and when
Ankylosaurus lived in the Late Cretaceous, from 68 to 66 million years ago (Maastrichtian age). Its remains come from United States and Canada, in the Hell Creek Formation.
The numbers
Length 7.5 m (estimates run from 7 to 8 m). Mass about 6.3 t. Hip height about 1.7 m. That is 4.4 human-lengths, or 0.67 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.