Yacimiento fosilífero de Chengjiang

The Chengjiang Fossil Site covers 512 hectares of hill country in Yunnan province, north of Lake Fuxian, and preserves the most complete record known of an Early Cambrian marine community. The core of the property is Maotianshan, a low hill running north-east to south-west, 3.71 by 2.56 kilometres, which contains a complete sequence of exposed and unexposed fossil-bearing strata, with an internal relief of barely 156 metres.

Its value lies in the exceptional quality of the preservation. The fossils retain the anatomy of hard and soft tissues across an enormous variety of organisms, invertebrate and vertebrate, because the shallow, muddy seabed on which they lived allowed fossilisation of extraordinary detail. At least sixteen phyla have been documented, along with several groups of enigmatic affinity and around 196 species, and some sources put the figure at more than 300 forms from more than twenty phyla. Among them are the oldest known fossil chordates, the phylum to which all vertebrates belong.

Chengjiang documents the Cambrian explosion, the episode of rapid diversification some 530 million years ago in which practically all today's major animal groups appeared, and it shows that complex community structures were established very early in that process, with food webs already topped by sophisticated predators and a wide variety of ecological niches. The site was discovered in 1984, declared a national geopark in 2001 and inscribed on the World Heritage List in 2012. There is no industrial activity and no permanent population within its boundaries, which are largely covered by secondary forest and scrub, and since 2017 it has had specific provincial protection legislation passed by the Yunnan People's Congress.