New research reveals that a remarkable collection of over 700 Ediacaran fossils from the late Ediacaran period indicates that significant animal groups, including the early ancestors of vertebrates, began diversifying millions of years earlier than previously believed.
The Ediacaran-Cambrian transition marked one of the most crucial turning points in Earth’s biological history.
However, the fossil evidence presents a fragmented view of this significant change, as Ediacaran biological communities are quite different from those of the Cambrian, leaving key moments of evolution elusive.
Dr. Gaorong Li from the University of Oxford states, “Our findings bridge a critical gap in the narrative of early animal diversification.”
“For the first time, we show that complex organisms typically associated with the Cambrian existed during the Ediacaran, indicating they evolved much earlier than fossil records previously suggested.”
In their study, Li and colleagues analyzed over 700 specimens from recently identified fossils in Yunnan province, China.
This fossil group, dating back 554 to 539 million years, is part of the intriguing Egawa biota.
Unlike many Ediacaran fossil sites that predominantly showcase traces of life on sandstone, these fossils are preserved as carbonaceous membranes, mirroring preservation styles found in renowned Cambrian sites like Canada’s Burgess Shale.
Dr. Luke Parry from the University of Oxford commented, “This groundbreaking discovery offers insight into a transitional phase in biological communities. The unique characteristics of Ediacaran life paved the way for the recognizable groups we categorize today.”
“Upon first examining these specimens, we recognized their uniqueness and the unexpected nature of our findings.”
The fossil group includes some of the earliest known relatives of deuterostomes, a category which now encompasses humans and vertebrates such as fish.
Among the specimens are ancestors of modern starfish alongside their close relative, the acorn worm (Ambulacraria), characterized by a U-shaped body attached to the seafloor with a stalk and tentacles for food capture.
Dr. Frankie Dunn from the University of Oxford noted, “It’s captivating that such exotic organisms thrived during the Ediacaran period.”
“We’ve discovered fossils that are distant relatives of starfish and sea cucumbers, and the search for more continues.”
The bicephalic fossils from the Egawa biota suggest that chordates (animals with backbones) also existed during this period.
Other noteworthy discoveries among the fossils include worm-like bilateral animals featuring complex feeding adaptations, as well as rare specimens believed to be early comb jellies.
Many specimens display unique anatomical features that do not correspond to any known Ediacaran or Cambrian species.
Dr. Ross Anderson from the University of Oxford stated, “Our findings suggest that the apparent scarcity of these complex faunas in other Ediacaran sites may highlight preservation discrepancies rather than an actual lack of diversity.”
“Carbonaceous compactions like those found in Egawa are uncommon in rocks of this age, indicating that similar communities may remain unpreserved elsewhere.”
For more on this pivotal discovery, refer to the research paper published in Science.
_____
Gaorong Li et al. 2026. Dawn of the Phanerozoic: The late Ediacaran transitional fauna of southwestern China. Science 392 (6793): 63-68; doi: 10.1126/science.adu2291
Source: www.sci.news
