|1.||of, denoting, or formed in the second period of the Mesozoic era, between the Triassic and Cretaceous periods, lasting for 55 million years during which dinosaurs and ammonites flourished|
|2.||the Jurassic the Jurassic period or rock system|
|[C19: from French jurassique, after the |
|Jurassic (j-rās'ĭk) Pronunciation Key
The second and middle period of the Mesozoic Era, from about 208 to 144 million years ago. During this time the supercontinent Pangaea continued to split up and numerous shallow seas inundated the new continents. Dinosaurs were the dominant form of terrestrial animal life, and the earliest birds appeared. Marine life was dominated by ammonites and belemnites, and sponges, corals, bryozoa, and gastropods all flourished. Gymnosperms and cycads were the dominant land plants. See Chart at geologic time.