Sauropelta

Chapter • Meet the dinosaur

Overview

Sauropelta was a nodosaurid ankylosaur, roughly five metres long and built like a low, armoured tank on four short, pillar-like legs. Its back and flanks were covered in rows of bony plates called osteoderms, embedded in the skin to form a continuous shield from the neck to the tip of the tail. Most striking of all were the long, tapering spines along the sides of the neck and shoulders, which grew larger towards the front; the foremost pair reached several tens of centimetres. The skull was low and triangular with a fairly narrow snout, and unlike the later ankylosaurids, Sauropelta had no tail club at all. Instead its tail was unusually long, making up close to half the total body length. Nodosaurids had scaly skin and osteoderms rather than feathers. Weighing somewhere around 1,500–2,000 kilograms, Sauropelta was no sprinter. It almost certainly moved at a steady walk, body held horizontally and the long tail carried clear of the ground. The broad hips and heavy shoulder girdle supported the armour, and the best defence was probably simply to stand its ground: a predator such as Deinonychus or Acrocanthosaurus would have faced a wall of bone and a hedge of forward-pointing neck spines. Those spines may also have served in display between individuals, for instance in contests over mates or territory. Sauropelta was a low browser, feeding on ferns, horsetails, cycads and other ground-level plants. The comparatively narrow snout suggests slightly more selective feeding than in some of its relatives. Its small, leaf-shaped teeth were too weak to grind tough plant matter thoroughly, so food was only roughly cropped and then fermented in a capacious gut — hence the broad, barrel-shaped body. The animal was named in 1970 by the American palaeontologist John Ostrom, working on material from the Cloverly Formation of Montana and Wyoming. The name means roughly "lizard shield", and the species name honours the Edwards family, on whose land fossils were collected. The epithet was originally published as edwardsi but has since been corrected to edwardsorum because it refers to more than one person. Sauropelta is one of the best-known nodosaurids, thanks to several partial skeletons preserving the armour in its original arrangement.

Chapter • Where it lived

Habitat

Sauropelta lived during the Early Cretaceous, roughly 115–108 million years ago, in what is now Montana and Wyoming, USA. Its fossils come mainly from the Cloverly Formation, especially the Little Sheep Mudstone Member. The landscape was a broad floodplain crossed by meandering rivers, with seasonal flooding, marshy patches and stands of conifers, ginkgoes and cycads, while ferns and horsetails carpeted the ground. Flowering plants were appearing but not yet dominant. The same environment was home to Tenontosaurus, Deinonychus and Acrocanthosaurus.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy