Tuojiangosaurus

Chapter • Meet the dinosaur

Overview

Tuojiangosaurus was a stegosaur roughly seven metres long, with a small, narrow skull, a strongly arched back and a tail that was carried clear of the ground rather than dragged. Around fifteen pairs of bony plates ran from the neck along the back and down the tail, becoming progressively more pointed towards the rear: the front ones were low and roughly triangular, while the rear ones turned into tall, spike-like structures. Two pairs of long spikes at the tail tip formed a thagomizer that the animal could swing sideways. The hind limbs were far longer than the forelimbs, giving the body its distinctive forward slope. Like all stegosaurs it walked on all fours and moved slowly. The head was held low, probably no more than half a metre above the ground, and the limb proportions suggest it was incapable of running at any real speed. The tail spikes, however, were a genuinely effective weapon against predators such as Yangchuanosaurus, which shared the same landscape. The back plates carry grooves for blood vessels and have been interpreted both as display structures and as armour, though in Tuojiangosaurus they were smaller and narrower than in the North American Stegosaurus. Its jaws held small, leaf-shaped teeth with no real chewing ability. Tuojiangosaurus therefore browsed on low vegetation – ferns, horsetails, cycads and young conifer shoots – and left the breakdown of that tough material to microbes in a capacious gut. The small mouth combined with a broad body implies that it spent a very large part of each day feeding. The fossils were found in 1974 during dam construction near Wujiaba in Zigong, Sichuan Province, China, in beds of the Upper Shaximiao Formation. The species was described in 1977 by Dong Zhiming together with Li Xuanmin, Zhou Shiwu and Zhang Yihong. The name means roughly "Tuo River lizard", while the species name multispinus refers to its many spines. The skeleton is one of the most complete stegosaur specimens from Asia and has become a museum favourite around the world.

Chapter • Where it lived

Habitat

Tuojiangosaurus lived about 163–157 million years ago, in the Late Jurassic (Oxfordian), in what is now the Sichuan Basin of southern China. The landscape was one of broad river floodplains and lakes surrounded by lush forest of conifers, cycads and ginkgoes, with dense ground cover of ferns. All known fossils come from the Upper Shaximiao Formation, above all from the Wujiaba locality near Zigong – an area that today hosts one of the richest dinosaur museums in the world.

Chapter • Wild behavior

Behavior & Ecology

Did you know?

Chapter • Scientific place

Taxonomy