This work is an international collaboration between Yunnan University, University of Exeter, the University of Saskatchewan, the Chinese Academy of Sciences, the University of Lausanne, and the University of Leicester. Maximiliano Paz, a postdoctoral fellow at the University of Saskatchewan who specializes in fine-grained systems, added: 'Access to sediment cores allowed us to see details in the rock which are commonly difficult to appreciate in the weathered outcrops of the Chengjiang area.' Gabriela Mángano, a palaeontologist at the University of Saskatchewan, who has studied other well-known sites of exceptional preservation in Canada, Morocco, and Greenland. 'It is hard to believe that these animals were able to cope with such a stressful environmental setting,' said M.

This contrasts with earlier research suggesting that similar animals colonised deeper-water, more stable marine environments. The results of this study are important because they show that most early animals tolerated stressful conditions, such as salinity (salt) fluctuations, and high amounts of sediment deposition. 'Application of this recently acquired knowledge to the study of fossiliferous deposits of exceptional preservation will change dramatically our understanding of how and where these sediments accumulated.'

'Our understanding of how these muddy sediments were deposited has changed dramatically during the last 15 years. 'Storm floods transported these organisms down to the adjacent deep oxygen-deficient settings, leading to the exceptional preservation we see today.'Ĭo-author Luis Buatois, a paleontologist and sedimentologist at the University of Saskatchewan, said: 'The Chengjiang Biota, as is the case of similar faunas described elsewhere, is preserved in fine-grained deposits. 'The unstable environmental stressors might also contribute to the adaptive radiation of these early animals.'Ĭo-lead author Farid Saleh, a sedimentologist and taphonomist at Yunnan University, said: 'We can see from the association of numerous sedimentary flows that the environment hosting the Chengjiang Biota was complex and certainly shallower than what has been previously suggested in the literature for similar animal communities.'Ĭhangshi Qi, the other co-lead author and a geochemist at the Yunnan University, added: 'Our research shows that the Chengjiang Biota mainly lived in a well-oxygenated shallow-water deltaic environment. 'The discovery of a deltaic environment shed new light on understanding the possible causal factors for the flourishing of these Cambrian bilaterian animal-dominated marine communities and their exceptional soft-tissue preservation.

'The Cambrian Explosion is now universally accepted as a genuine rapid evolutionary event, but the causal factors for this event have been long debated, with hypotheses on environmental, genetic, or ecological triggers,' said senior author Dr Xiaoya Ma, a palaeobiologist at the University of Exeter and Yunnan University.

Life of delta