Fossils from China show complex life evolved millions of years earlier than once thought

Key Points:

• Newly discovered fossils from the Jiangchuan Biota site in southwestern China, dating to the Ediacaran period (554-539 million years ago), reveal detailed impressions of complex animals, pushing back the emergence of complex life by at least 4 million years before the Cambrian explosion.
• The fossils include a variety of creatures such as goblet-shaped jellies, sausage-like worms with visible guts, and segmented, tentacled animals resembling Cambrian species, blurring the distinction between Ediacaran and Cambrian life forms.
• Many specimens exhibit bilateral symmetry, a trait common in modern animals, and some fossils potentially represent early deuterostomes, the group that includes vertebrates, indicating vertebrate ancestors existed during the Ediacaran.
• The exceptional preservation of these fossils allows unprecedented insight into early animal evolution, but classifying these ancient species remains challenging due to limited fossil features and lack of DNA evidence.
• While the Cambrian period still marks significant diversification and emergence of new animal phyla, these findings suggest the evolutionary groundwork began earlier, prompting further research into the biology and ecology of these ancient organisms.