An assemblage of fossil organisms found in deposits of Maotianshan shale in Chengjiang County, Yunnan Province, China, dating from the lower Cambrian (about 525 million years ago). Discovered in 1984, the Chengjiang fossils represent a great diversity of animal forms, including well-preserved soft tissues, and are comparable in importance with the slightly younger Burgess shale fossils. Some 250 fossil species have been identified, including numerous arthropods, worms, sponges, cnidarians, and ctenophores, plus several chordates, including a jawless fish named Myllokunmingia, discovered by Chinese palaeontologist Degan Shu in 1999. It resembles a hagfish and is one of the oldest known fossil vertebrates to date. Another fossil vertebrate, the eel-like Zhongjianichthyes, was found in 2003. UNESCO gave the site World Heritage status in 2012. See also cambrian explosion.