Period: Early Jurassic
Order, Suborder, Family: Ornithischia, Thyreophora, Scelidosauridae
Location: Europe (England)
Length: 13 feet (4 meters)
Scelidosaurus was first discovered in the middle of the 19th century in Early Jurassic rocks from southern England. Sir Richard Owen, creator of the name Dinosauria, described its remains. He named it Scelidosaurus, which means "limb reptile," referring to its large legs.
It was the earliest known ornithischian dinosaur and one of the most complete for its time. However, with the discovery of Lesothosaurus and Heterodontosaurus in the 1960s and 1970s, scientists know that Scelidosaurus is not the oldest ornithischian. But it still remains an important animal in the history of dinosaurs. It tells scientists much about the early evolution of ornithischians, particularly stegosaurs and ankylosaurs, the armored dinosaurs from later in the Mesozoic Era.
Scelidosaurus was a plant-eating dinosaur that grew to about 13 feet. It was a heavily built animal. The most unusual feature of Scelidosaurus was that it had many bony plates in the skin of its back and rib cage. These plates were not like the high, thin plates that extended from the backbone of stegosaurian dinosaurs. These plates were similar to the bony armor of ankylosaurs.
The large head of Scelidosaurus was equipped with somewhat simple, leaf-shaped teeth. From the teeth and the shape of the skeleton, scientists know that Scelidosaurus was a plant-eating animal. It likely ate a mixture of leaves of shrubs and low-lying branches, but may also have fed on succulent fruits and even eaten insects as a hatchling and juvenile.
The legs of Scelidosaurus were stout and the feet had four toes. The size and shape of the legs show that Scelidosaurus walked on all four legs. The tail of Scelidosaurus was long compared to most other ornithischian dinosaurs. The tail also had armor in the skin.
Recently, new discoveries of Scelidosaurus have been found from the area where the original fossils were unearthed. These include skull bones and the impressions of small, rounded scales in the skin. These skin impressions are rare fossils. They are helpful for scientists when they try to reconstruct the appearance of dinosaurs and to understand the biology of these extinct animals.
Scelidosaurus is one of the most primitive armored dinosaurs, along with its close relative Scutellosaurus, which also lived in the Early Jurassic. Both are early members of the group of dinosaurs that contains both stegosaurs and ankylosaurs (Thyreophora). Scelidosaurus is closely related to the Late Jurassic stegosaurs Huayangosaurus and Stegosaurus. It is also related to the Late Jurassic ankylosaur Sarcolestes and the Late Cretaceous ankylosaur Shamosaurus. Lusitanosaurus may also be related; it is known only from a fragment of the snout and was found in Late Jurassic rocks along the coast of Portugal.