Chengjiang fossil site, Yunnan

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A Cambrian Lagerstätte in the Maotianshan Shales near Chengjiang in Yunnan Province, southwest China, found by Hou Xianguang in 1984 and roughly ten million years older than the Burgess Shale at about 518 million years. Chengjiang matters for two reasons that the Burgess Shale cannot supply on its own. First, it preserves a comparably diverse soft-bodied fauna on the opposite side of the Cambrian world, which shows that the Burgess assemblage is not a local peculiarity. Second, being older, it sits closer to the radiation itself, and it contains the earliest widely accepted chordates — Myllokunmingia and Haikouichthys, small fish-like animals with what appear to be a notochord, myomeres and gill structures. Preservation at Chengjiang differs chemically from the Burgess Shale, with soft tissues often replicated in iron-rich minerals rather than as carbon films, which means the two deposits filter their faunas differently and comparing them is not straightforward. The site was inscribed as a UNESCO World Heritage Site in 2012.