Chengjiang Fossil Site, World Heritage Site, China
The rocks and fossils of the Chengjiang Fossil Site present an extraordinarily preserved record that testifies to the rapid diversification of life on Earth during the early Cambrian period, 530 million years ago. In this geologically short interval, almost all major groups of animals had their origins.
The diverse geological evidence from the Chengjiang Fossil Site presents fossil remains of the highest quality of preservation. It is also one of the earliest records of a complex marine ecosystem and a unique window of understanding into the structure of early Cambrian communities.
The site was discovered in 1984 and was inscribed on the World Heritage List in 2012, following IUCN’s recommendations. It is one of the most important paleontological sites in the world representing an outstanding example of a major stage in the history of life.
Featuring in Sir David Attenborough’s latest documentary series, The Rise of Animals, it is coined by the distinguished conservationist as “a site of a thrilling discovery that has given us new evidence for the very first vertebrates.”
The exceptional record of rare anatomical detail and beauty includes fossils from 152 different species. Many of these species, especially the soft-bodied ones, are unique to this fossil site and provide direct evidence of the origin of animal diversity.
Size and location
Chengjiang Fossil Site is a relatively small strip of land located in the eastern part of Chengjiang County in south China’s Yunnan Province. The area consists of a hilly land with an elevation of 156m. Its well-defined boundaries encircle over 500ha and are surrounded by a 220ha-buffer zone that does not form part of the World Heritage property.
The natural site includes a sequence of exposed and unexposed strata, and fossil horizons. Today it is largely covered with secondary forest and shrub and there is no industrial activity or permanent human habitation. It is also protected under a zoning scheme associated with Chinese Geoparks.
Fauna and flora
Pushing the emergence of proto-vertebrates back in time to the Early Cambrian, Chengjiang’s fossil record is extremely important for our understanding of early multi-cellular life. Two species found within the site, Yunnanozoon lividum and magnificissimi, may be the oldest known hemichordates, a wormlike marine animal.
Fauna appears in beds dating back as far as 530 million years ago and is estimated to be from a geological interval of a 2- to 3-million-year duration. Fossils are found in the yellowish-weathering grey mudstone and shale found in a formation known as the Yu’anshan Member. This area can be divided into four sections.
The bottom section, made of black siltstone, contains the oldest trilobites in China, such as Parabadiella, together with the bradoriids Hanchiangella, Liangshanella and Nanchengella, amongst others.
We then find an interval of black siltstone and shale featuring mainly trilobites, such as Tsunyidiscus and Wutingaspis, and the bradoriids Hanchungella and Emeillopsis, but none of Chendjiang’s key soft-bodied fauna.
The soft-bodied fossils are found in the higher interval, a yellowish-green shale interbedded with siltstones and sandstones. This contains a extremely rich variety of arthropods such as Naraoia, Leanchoilia, Isoxys, Kunmingella, Eoredlichia and Yunnanocephalus, as well as lobopodians, eldoniids, worms and sponges.
The highest section, above the 100m mark, is a yellow silty sandstone with less fauna fossils. Only some trilobites can be seen, such as Eoredlichia and Yunnanocephalus, some bradoriid such as Kuanyangia and Kunmingella, and the brachiopods Lingulella and Lingulepis.
Chengjiang Fossil Site has clear boundaries and contains the most significant rock exposures of the region. It has a buffer zone that provides wider protection, although some fossil evidence exists beyond the boundaries and buffer zone.
In 2004, the buffer zone counted 14 phosphate mining operations, which have all been closed down since 2008. Restoration is ongoing and will take some time. Thankfully, the site itself has not been affected by mining activity and the County and Provincial governments have committed not to open or re-open mines.
The construction of a path and a museum in the two key fossil sites has had an impact on the integrity of the property. However, future infrastructure development within the World Heritage boundaries has been restricted and any development with a potential impact will be reviewed before being approved.
Visitor numbers are expected to grow from 4-5,000 in 2012, most of whom are locals or individuals from neighbouring areas and visiting scientists, to an estimated 30-40,000. This increase will need to be strategically managed and carefully regulated by providing guides, designating restricted areas and banning fossil collecting.
Long-term conservation of Chengjiang Fossil Site will require effective land-use planning in surrounding areas. In particular, fossil sites outside boundaries can provide context for understanding the value of this precious gift of nature.