Stegouros

Stegouros is an extinct ankylosaur genus that lived during the Late Cretaceous period in the southernmost region of Chile, Magallanes. The generic name combines the Greek stegos, meaning “roof” and oura, meaning “tail”, referring to the roof-like covering of the tail end. 

Measuring approximately 2 meters in length, Stegouros was a relatively small herbivorous dinosaur. It possessed a unique tail weapon, unlike any other known dinosaur, characterized by a flat, frond-like structure formed by pairs of laterally projecting osteoderms that covered the distal half of its tail. While exhibiting ankylosaurian cranial features, its postcranial skeleton was largely primitive, with some stegosaur-like traits.

Phylogenetic analyses have placed Stegouros within the group Ankylosauria, and it is specifically related to Kunbarrasaurus from Australia and Antarctopelta from Antarctica. These three dinosaurs form a clade of Gondwanan ankylosaurs, which diverged earliest from all other ankylosaurs. Notably, Antarctopelta’s large osteoderms and specialized tail vertebrae also suggest the presence of a tail weapon similar to that of Stegouros.