A newly discovered trove of fossils in southwestern China is shifting the timeline of when complex animals evolved.
The diversity and complexity of animal life is thought to have increased rapidly beginning around 539 million years ago, in an evolutionary burst known as the Cambrian explosion. But the new fossil site suggests that some of that complexity was already present several million years before the Cambrian explosion, during the end of the Ediacaran period (roughly 635 million to 539 million years ago).
