Jurassic Jurassic The Jurassic (; from Jura Mountains) was a geologic period and system that spanned 56 million years from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period Mya. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles. The start of the period was marked by the major Triassic–Jurassic extinction event. Two other extinction events occurred during the period: the Pliensbachian-Toarcian extinction in the Early Jurassic, and the Tithonian event at the end; however, neither event ranks among the "Big Five" mass extinctions. The
Wasson Bluff dinosaur tracks, at his Parrsboro Rock and Mineral Shop and Museum. One of them, also found at Wasson Bluff, is a track that may have been made by a primitive, two-legged, crocodile-like creature that was nearly long. In January 1986, American paleontologists Paul Olsen and Neil Shubin announced they had recovered hundreds of thousands of bones at Wasson Bluff, the largest fossil find in North America dating from the geological period 200 million years ago known as the Triassic-Jurassic boundary. It was a time when massive lakes of lava spewed from fissures in the earth as the supercontinent Pangea broke