Lesothosaurus

Phylogeny: Dinosauria > Ornithischia > Genasauria > Thyreophora (?)

Overview: The exact phylogenetic status of Lesothosaurus has been debated. It clearly belonged to the Ornithischia, but the specifics of its relationship with others in the group aren’t fully clear. Originally, the genus was seen as a basal ornithopod, possibly belonging to the supposed family Fabrosauridae. In most modern studies, the Fabrosauridae has been shown to be an invalid grouping, however. Later, Lesothosaurus was classified as a basal member of the Neornithischia – the clade leading to “duck-billed” and horned dinosaurs. Alternatively, however, Lesothosaurus has also been classified as one of the most basal known members of the clade Thyreophora, which contained the heavily armored stegosaurs and ankylosaurs. Its skull features do imply this to be the case, but it lacked armor. Early thyreophorans, however, probably did have limited armor, were lightly built, and walked bipedally.

Lesothosaurus was a rather small dinosaur at maybe two meters long. It was slender and probably fast on its feet, its agility being the best defense it had without armor adaptations. The animal had a fairly narrow, pointed snout, tipped by a keratinous beak. Small teeth were situated farther back in its mouth, which were somewhat similar to those seen on some thyreophorans. Lesothosaurus may’ve been a selective browser, preferring certain ground-level plants. It itself may’ve been prey for dinosaurs like Dracovenator – a possible relative of North America’s Dilophosaurus. Fossils of both Lesothosaurus and Dracovenator come from the upper layers of the Elliot Formation, in what is now South Africa and Lesotho. The first specimen of Lesothosaurus was found in the latter, back in the late 1950’s. Described in 1978, its generic name honors its nation of origin.