Animal life exploded in diversity and form during the Cambrian period about 500 million years ago. An international team of paleontologists has discovered an early Cambrian fossil site in China — the Qingjiang biota — that contains a variety of specimens, more than half of which are previously undescribed. The 518 million-year-old fossil site rivals previously described Cambrian sites, such as the Burgess Shale of British Columbia and the Chengjiang fossil site in China’s Yunnan province, and should help to elucidate biological innovation and diversification during the Cambrian period.

A little more than 500 million years ago, early animal life on Earth exploded in diversity and form in an evolutionary event that would graft the initial branches of most major animal phyla onto the tree of animal life — the Cambrian explosion.

Much of what is known about the Cambrian explosion has been learned from the fossil record at sites where the geological echoes of this early life have been preserved.

Perhaps no other assemblages to date have been more important to our understanding of the Cambrian explosion than the Burgess Shale and Chengjiang localities — both of which contain large and diverse collections of well-preserved fossils, including soft-bodied organisms, which rarely make it into the fossil record.

The discovery of the Qingjiang site — new Burgess Shale-type Lagerstätte (a geologist’s term for a deposit of extraordinarily well-preserved fossils) — was made by Northwest University’s Dr. Dongjing Fu and colleagues from Guizhou University, Northwest University and Pomona College almost by accident.

The paleontologists were working in the mountains and came down to the banks of the Danshui River, located in Hubei Province, when they noticed some rocks had an odd pin-striped pattern — a telltale sign of layers of mud deposited rapidly by ancient storms similar to those found at the famous Chengjiang site.

In addition to the high taxonomic diversity, Qingjiang fossils are characterized by near-pristine preservation of soft-bodied organisms — including juvenile or larval forms, arthropod and worm cuticles and jellyfishes — and such soft-tissue features as eyes, gills and guts.

More than 4,000 specimens have already been collected, with 101 species identified — of these species, 53 are new to science and names have to yet to be assigned.

“This finding enriches our view of the early animal world and offers us really remarkable views of the simplest animals,” said team member Professor Robert Gaines, from Pomona College.

“One of the most incredible things about this finding is the pristine condition of many of these specimens — fossils that haven’t been substantially affected by impacts of time, and in them you can clearly see soft tissues like eyes, tentacles and gills.”

“The discovery promises to shed light on the evolution of Cambrian ecosystems across space and time. Nowhere do have a more pristine fossil record of early Cambrian life and such a diversity of organisms — and this is just the beginning.”

A paper reporting this discovery is published in the journal Science.

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Dongjing Fu et al. 2019. The Qingjiang biota — A Burgess Shale-type fossil Lagerstätte from the early Cambrian of South China. Science 363 (6433): 1338-1342; doi: 10.1126/science.aau8800