Ankylosaurus

Chapter • Meet the dinosaur

Overview

Ankylosaurus magniventris was among the most heavily armoured animals ever to walk on land. Its body was low, broad and barrel-shaped — the species name magniventris literally means "great belly" — and could measure up to about 1.5 metres across the hips. The back, neck and flanks were covered in bony plates called osteoderms, embedded in the skin to form a continuous mosaic of armour. Even the eyelids were reinforced with bone, and four pyramid-shaped horns projected from the rear corners of the skull. At the end of the stiffened tail sat a massive club of fused bone. Recent work by Victoria Arbour and Jordan Mallon (2017) puts the animal at roughly 6–8 metres long and 5–8 tonnes in mass. Ankylosaurus walked on all fours on broad feet with sturdy, slightly splayed limbs; no feathers or feather-like structures are known from armoured dinosaurs.

Chapter • Where it lived

Habitat

Ankylosaurus lived during the very last two million years of the Cretaceous, in the Maastrichtian stage roughly 68–66 million years ago, in what is now western North America. The landscape was a mosaic of broad coastal floodplains along the retreating Western Interior Seaway, with meandering rivers, damp conifer and fern woodland, and more open ground dotted with early flowering plants. Fossils come from the Hell Creek Formation of Montana and South Dakota, the Lance Formation of Wyoming, and the Scollard and Frenchman formations of Alberta and Saskatchewan in Canada. The holotype, AMNH 5895, was collected by Barnum Brown in Montana in 1906 and described in 1908, while the Canadian skull CMN 8880 is the largest specimen known. Ankylosaurus was one of the last non-avian dinosaurs on Earth, disappearing in the asteroid impact 66 million years ago.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy