LATE CRETACEOUS PERIOD: 70 - 65 million years ago
Fossils of Thescelosaurus neglectus were first discovered in 1913 in the upper layer of the Late Cretaceous in North America. It gets its "neglected" name from the fact that it was not further studied or identified until 22 years after its discovery. This dinosaur is considered a member of the small ornithopod or "bird-hipped" dinosaurs.
The most fascinating recent discovery surrounding this dinosaur relates to a specimen unearthed in South Dakota, U.S.A. in 1992. Preserved internal remains were subjected to a CAT scan and revealed a strong, advanced four-chamber heart like mammals, not reptiles! This has caused great controversy and further adds proof that dinosaurs were warm-blooded creatures.
Thescelosaurus was an herbivore. Unlike some of its relatives, this dinosaur was bulkier and likely not a swift runner. With its long tail, Thescelosaurus grew to a length between 10 to 13 feet with a height of around 3.5 feet. A full-grown dinosaur may have weighed up to 500 pounds. Small armor plates afforded protection down its back and five-finger hands and four-toe feet possessed pointed claws. Unique to this dinosaur and different to hypsilophodonts ('high ridge tooth") are the presence of teeth in the front of Thescelosaurus' upper jaw and five fingers on each hand instead of three or four. Thescelosaurus' thigh bone is the same length as its shin bone whereas hypsilophodonts have longer shin bones. This feature indicates Thescelosaurus was not a graceful sprinter but moved in a more deliberate and slower manner.
Thescelosaurus bones, other than toe phalanges, are rare in the fossil record because the bones are hollow and therefore fragile. While individual bones have been discovered, articulated or associated skeletons are extremely rare.
Thescelosaurus fossils have been found only in North America.