Scelidosaurus

Scelidosaurus is a genus of herbivorous armored dinosaurs from the Early Jurassic period, known from fossils found in what is now England. It is one of the earliest members of the Thyreophora, the group that later gave rise to stegosaurs and ankylosaurs, and is often considered a basal or stem member near the origin of armored dinosaurs. The type species, Scelidosaurus harrisonii, was named by Richard Owen in the 1860s after the early fossil discoveries in Dorset.

Anatomy and posture of Scelidosaurus suggest a relatively small to medium-sized animal, with an elongated body and a cover of bony osteoderms (scutes) along the back and sides. The limbs indicate a capable, possibly primarily quadrupedal gait, though some reconstructions have allowed for occasional bipedal movement. The skeleton reveals a long tail and a skull adapted to processing vegetation, including a beak-like mouth and teeth suitable for cropping plant matter. Early reconstructions sometimes portrayed it as more bipedal, but the available evidence supports a herbivorous body plan with stout, armored protections.

Classification and significance place Scelidosaurus as a crucial early example of dinosaur armor and as a key data point in studying the evolution of Thyreophora. Its fossils, primarily from the Early Jurassic rocks of Dorset, England, contributed to understanding the early diversification of ornithischian dinosaurs and the morphological experimentation that led to later armored dinosaurs. Scelidosaurus remains one of the best-known early dinosaurs due to its relatively complete skeleton and its historical importance in dinosaur research.