二叠纪和三叠纪是衔接古生代和中生代的两个地质时代，在这个地质时期内，世界上出现了板块大联合--泛大陆，发生了地史上最大规模的生物更替。从早二叠世开始到晚二叠世，世界上发生过巨大规模的海退，显示出古气候、古海洋方面许多变化，对古地理环境造成了巨大的影响。早三 The Permian and Triassic are two geological times connecting the Paleozoic and Mesozoic. During this geologic period, there appeared a great association of plates in the world - the Pan-Continental. The largest biological alteration took place in history. From the beginning of the Early Permian to the late Permian, a huge scale regression occurred in the world, showing many changes in paleoclimate and ancient oceans, which have had a tremendous impact on paleogeography. As early as three