Huayangosaurus

Chapter • Meet the dinosaur

Overview

Huayangosaurus was a small, stocky stegosaur, roughly four to nearly five metres long and probably weighing somewhere between half a tonne and a tonne — no bigger than a large car. It walked on all fours, but its forelimbs were relatively long compared with later relatives such as Stegosaurus, so its back sloped less steeply and its posture was more level. A double row of plates and spikes ran along the neck, back and tail, narrower and spikier than the broad plates of Stegosaurus, and the tail ended in four long defensive spikes — a thagomizer. A stout parascapular spine also jutted sideways from each shoulder, a feature later stegosaurs lost.

Chapter • Where it lived

Habitat

Huayangosaurus lived in the Middle Jurassic, about 168–161 million years ago, in what is now Sichuan Province in southern China. Every known specimen comes from the Lower Shaximiao (Xiashaximiao) Formation in the famous Dashanpu quarry outside the city of Zigong, where dozens of dinosaur skeletons have been excavated since the late 1970s. The setting was a humid, subtropical river valley with broad floodplains, meandering channels, lakes and forests of conifers, ginkgoes, ferns and cycads. Huayangosaurus shared this landscape with long-necked sauropods such as Shunosaurus and Omeisaurus, the small ornithopod Xiaosaurus and the predator Gasosaurus.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy