Shunosaurus

Chapter • Meet the dinosaur

Overview

Shunosaurus was a comparatively small sauropod, reaching about 9–11 metres in length and an estimated 2.5–4 tonnes in weight. Next to the later giants of its group it looks almost compact: the neck held only twelve vertebrae, the body was barrel-shaped and the limbs were short and pillar-like. The skull was blunt and relatively deep, packed with numerous closely spaced, spoon-shaped teeth — more teeth than most other sauropods carried. Its most striking feature, however, sat at the far end: the tail tip was fused into a bony club bearing two pairs of short spikes, a weapon known from only a handful of sauropods. Like all sauropods it walked on four legs, holding its tail clear of the ground and its backbone roughly horizontal; no trackway shows sauropods dragging their tails. The tail club is usually interpreted as a defensive weapon against predators such as Gasosaurus, though it may equally have been used in display or in contests between members of its own species. Because the neck was short, Shunosaurus probably browsed at ground level and up to perhaps four metres, rather than reaching into the canopy the way the long-necked Omeisaurus and Mamenchisaurus could. Its diet consisted of ferns, horsetails, cycads, ginkgos and conifers. The crowded, spatulate teeth cropped and stripped plant material, while the real work of digestion happened in a large fermentation chamber in the gut. Heavy tooth wear and rapid replacement rates show that the animal fed on tough, abrasive vegetation day after day. Shunosaurus lii was described in 1983 by Dong Zhiming, Zhou Shiwu and Zhang Yihong, based on material from the Dashanpu quarry near Zigong in Sichuan, China. The site turned out to be one of the world's richest Jurassic bone beds, and more than twenty individuals of Shunosaurus have been recovered there, several with skulls preserved. That makes it one of the best-known sauropods of all — its skull is among the very few nearly complete sauropod skulls from the Middle Jurassic. The tail club came to light only later, at the end of the 1980s, and took palaeontologists by surprise.

Chapter • Where it lived

Habitat

Shunosaurus lived during the Middle Jurassic, roughly 170–160 million years ago, in what is now Sichuan in south-western China. All confirmed remains come from the Xiashaximiao Formation, above all from the Dashanpu bone bed just outside the city of Zigong. The setting was a humid, subtropical floodplain of meandering rivers, lakes and shallow channels, framed by dense stands of ferns, horsetails, cycads, ginkgos and conifers. The bone bed preserves an entire ecosystem: the sauropods Omeisaurus and Datousaurus, the spiky stegosaur Huayangosaurus, the small plant-eaters Agilisaurus and Xiaosaurus and the predator Gasosaurus, alongside fish, turtles and crocodile relatives.

Chapter • Wild behavior

Behavior & Ecology

Did you know?

Chapter • Scientific place

Taxonomy