Jiangchuan Biota: 700 Exceptionally Preserved 3D Fossils from Yunnan Push Cambrian Explosion Origins Back Millions of Years

A landmark Science paper published in April 2026 has rewritten the timeline of animal evolution. Researchers from Yunnan University and Oxford University’s Museum of Natural History have described the Jiangchuan Biota—more than 700 three-dimensionally preserved animal fossils from Yunnan Province, China, dating to 554–539 million years ago in the late Ediacaran Period.

These carbonaceous compression fossils capture complex, mobile animals with preserved guts, feeding structures, and internal organs—features previously known only from Cambrian deposits. Among the finds are early deuterostomes (ancestors of starfish, sea urchins, and vertebrates including humans), worm-like bilaterians, and other mobile creatures that lived three-dimensional lives in the water column.

“This discovery closes a major gap,” said lead author Gaorong Li. “For the first time, we demonstrate that many complex animals normally found only in the Cambrian were already present in the Ediacaran, meaning they evolved much earlier than fossil evidence previously showed.”

The Jiangchuan ᴀssemblage bridges the enigmatic Ediacaran world of simple, often sessile organisms with the explosive diversification of the Cambrian. It reveals that key animal body plans and ecological roles had already emerged at least four million years before the conventional start of the Cambrian Explosion (~538–530 Ma).

Exceptional preservation—rare for Ediacaran rocks—allowed detailed reconstruction of soft tissues, showing these animals actively moved, fed, and interacted in ways once thought impossible before the Cambrian. The site demonstrates that the “explosion” was not a sudden burst but the culmination of a longer, more gradual diversification already underway in the Ediacaran.

The Jiangchuan Biota transforms our view of life’s early history: complex animals did not appear overnight 535 million years ago—they had deep roots stretching back into the Precambrian. China’s fossil-rich beds have once again delivered a game-changing window into the true tempo of animal origins.