Pinacosaurus

Pinacosaurus is a quintessential Asian ankylosaur discovered during the famous Central Asiatic Expeditions of the 1920s. Known from dozens of specimens spanning both Mongolia and China, it is among the best-documented armoured dinosaurs in the fossil record. Adults reached lengths of around five metres, bearing a light and slender skull compared to those of its relatives. The snout featured multiple complex nasal openings whose exact function remains debated. Pinacosaurus is especially notable for remarkable fossil beds containing groups of young individuals resting together, pointing towards social behaviour and herd grouping among juveniles. These groups were probably caught and smothered simultaneously during severe Cretaceous sandstorms. Armed with a bony tail club and protective osteoderms, it was an effective defender against dromaeosaurids and tyrannosauroids.

Spectacular bonebeds have preserved groups of juvenile Pinacosaurus huddled together, likely buried by sandstorms.

Where and when

Pinacosaurus lived in the Late Cretaceous, from 80 to 75 million years ago (Campanian age). Its remains come from Mongolia and China, in the Djadokhta Formation.

The numbers

Length 5.3 m (estimates run from 5 to 5.5 m). Mass about 1.7 t. Hip height about 1.4 m. That is 3.1 human-lengths, or 0.47 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.

Compare Pinacosaurus with a bus Place on the timeline