ˌdīnəˈsȯrēə noun plural
Usage: capitalized
Etymology: New Latin, from din- + -sauria
: a group of extinct reptiles widely distributed from the Triassic to the Mesozoic initially differing little from the generalized long-tailed quadrupedal common ancestors of modern birds and crocodilians but later becoming specialized for chiefly terrestrial carnivorous or herbivorous modes of life into distinct bipedal and quadrupedal groups, the latter including the largest known land animals — compare brontosaurus , diplodocus , ornithischia , saurischia , thecodontia