Sauropelta: The armoured plant-eater of the Early Cretaceous

Sauropelta is the museum dinosaur that looks as though it is wearing a suit of armour: its back is covered in bony plates and large spikes rise from its shoulders. It was a nodosaurid ankylosaur that lived during the Early Cretaceous in western North America. Unlike the better-known club-tailed ankylosaurs, Sauropelta had no bony club at the end of its tail.

Its body

Sauropelta had a low, sturdy body carried on four legs. Its most striking feature is the rows of bony plates, or osteoderms, running from its neck over its back, each like a small rounded shield. Large, thick spikes also stick out from the sides of its neck and shoulders, like natural shoulder pads. In life, these plates and spikes were probably covered by a horny sheath, so the living animal looked fuller and warmer than the bare fossil.

Its head was small for its body, with a beak-like mouth for cropping low plants.

Where it lived and what it ate

Sauropelta was a plant-eater, feeding on ferns, cycads and shrubs near the ground. Its low body suggests it may have browsed close to the ground like many herbivores today. Although it had no tail club, its back armour and shoulder spikes may have offered some defence. Whether it lived in herds or alone is not yet clear from the evidence.

Where its fossils were found

Most Sauropelta fossils come from western North America, especially the United States. The name Sauropelta means "shield", a very fitting label for its shape. One exceptionally preserved specimen has revealed a great deal about the structure of its osteoderms and their horny covering.

What the fossils tell us — and what they do not

Fossils reveal the arrangement and general shape of the armour, but the colour of the horny sheath, the pattern on its body and exactly how it moved day to day have to be inferred. So the colours and details here are evidence-informed reconstructions.

A note for grown-ups

You could help a child compare "armour" with "tail club": both are ankylosaurs, so why does one have a club and the other not? Learning to compare is the first step to understanding biological diversity.