Guanling Formation

The Guanling Formation is a Middle Triassic marine formation in Guizhou Province, southwestern China, roughly two hundred and forty million years old, preserving an exceptionally diverse fauna of marine reptiles, fish and invertebrates within finely layered limestone, most famously at the Luoping fossil site. The formation has yielded some of the best evidence anywhere for the rapid recovery of marine ecosystems after the end-Permian mass extinction.