A locale in southwestern China harbors a remarkable collection of unusual life-forms that predated the Cambrian explosion, pushing back the genesis of intricate life by eons.
An artist’s reconstruction of Jiangchuan biota (~554-539 million years ago).(Image credit: Xiaodong Wang)Subscribe to our newsletter
A recently unearthed cache of fossils in China’s southwest region is altering the chronology of when sophisticated animals came into being.
The proliferation and sophistication of animal existence are believed to have surged commencing around 539 million years ago, during a period of rapid evolutionary advancement termed the Cambrian explosion. However, the new fossil site indicates that some of this complexity was already in existence several million years preceding the Cambrian explosion, during the latter part of the Ediacaran period (approximately 635 million to 539 million years ago).
“One fossil bears a striking likeness to the sandworm from the novel Dune,” remarked study co-author Frankie Dunn, a researcher specializing in Ediacaran organisms at the Oxford University Museum of Natural History, in a statement.
While certain basic multicellular organisms, such as sponges, first emerged during the Ediacaran period, the majority of extant animal phyla appeared during the subsequent Cambrian explosion, which lasted 13 million to 25 million years, encompassing chordates, the phylum to which humans and other vertebrates belong.
The Haootia-like fossil (an early cnidarian – the phylum that includes jellyfish, sea anemones and corals) from the Jiangchuan Biota (~554-539 million years old). (Image credit: Gaorong Li & Xiaodong Wang.)
The novel fossil discovery suggests that a degree of that complexity had already emerged by the late Ediacaran. Discovered as part of the Jiangchuan Biota fossil assemblage in southwestern China, the collection encompasses over 700 specimens of fossilized fauna and flora dating from 554 million to 539 million years ago. Researchers documented these findings on Thursday, April 2, in the journal Science.
“Upon initial examination of these specimens, it became evident that we were dealing with something entirely novel and unanticipated,” stated study co-author Luke Parry, a paleobiologist affiliated with the University of Oxford.
The fossils from this location primarily consist of flattened impressions of organisms on the surrounding rock, known as carbonaceous films. Unlike three-dimensional impressions left by robust bodily components like bones and shells, carbonaceous films preserve certain details of an organism’s soft anatomy, including its digestive tract and feeding apparatus.
This less-prevalent preservation method might offer an explanation for why scientists have not previously encountered evidence of these more intricate animals in the Cambrian period.
“Our findings imply that the apparent scarcity of these complex animal groups at other Ediacaran sites may stem from variations in preservation rather than genuine biological absence,” explained study co-author Ross Anderson, a researcher at the Oxford University Museum of Natural History who investigates the evolution of complex life. “Carbonaceous compressions, such as those found at Jiangchuan, are uncommon in rocks of this geological age, suggesting that comparable communities may not have been preserved elsewhere.”