Stegouros

Stegouros was a small, extraordinarily specialised armoured dinosaur discovered in the Late Cretaceous Dorotea Formation of Chilean Patagonia. Measuring barely two metres in total length, it represents a distinctive southern lineage of armoured dinosaurs known as the Parankylosauria. Unlike northern ankylosaurids that bore heavy bony clubs or nodosaurs with prominent shoulder spikes, Stegouros developed a unique weapon resembling an Aztec macuahuitl flat war club, constructed from seven pairs of fused dermal osteoderms encasing the rear of its tail. It walked low to the ground on four legs, using its cropped beak and leaf-shaped teeth to feed on low-growing shrubs and fern greenery. Its near-complete fossil preservation sheds vital light on Gondwanan dinosaur evolution, revealing that southern armoured dinosaurs followed a distinct evolutionary path.

Its tail weapon resembled a macuahuitl, formed of fused osteoderms encircling the tail tip like blade-like fronds.

Where and when

Stegouros lived in the Late Cretaceous, from 74.9 to 71.7 million years ago (Campanian-Maastrichtian age). Its remains come from Chile, in the Dorotea Formation.

The numbers

Length 1.9 m (estimates run from 1.8 to 2 m). Mass about 98 kg. Hip height about 0.5 m. That is 1.1 human-lengths, or 0.17 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.

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