The fossils were uncovered at a site in Yunnan Province, southwestern China. The study detailing the find was published in the journal Science, and the research was led by scientists from Oxford University and Yunnan University. This extensive collection provides new insights into the early diversification of animal life.
The significance of this discovery lies in its challenge to previous evolutionary timelines. Previously, it was thought that the rapid diversification of complex animal life, known as the Cambrian explosion, began around 535 million years ago, but these fossils indicate that many complex animals existed in the Ediacaran period, earlier than previously demonstrated by fossil evidence. According to Dr Gaorong Li, lead author of the study, this demonstrates for the first time that many complex animals, normally only found in the Cambrian, were present in the Ediacaran period, meaning they evolved much earlier than previously shown by fossil evidence.
The presence of these ambulacrarians in the Ediacaran period is really exciting.
This shift suggests that the roots of modern animal groups extend further back in time, though how exactly these complex animals evolved and diversified during the Ediacaran period remains unclear. Specific findings from the fossils include the oldest known relatives of deuterostomes, the group that encompasses vertebrates like humans and fish. Ancestors of starfish and acorn worms, part of the Ambulacraria group, were also identified among the fossils.
According to Dr Frankie Dunn, a co-author and paleontologist at Oxford University's Museum of Natural History, the presence of these ambulacrarians in the Ediacaran period is really exciting. These identifications help bridge gaps in the evolutionary tree, but what specific new, undescribed animal forms were found among the fossils has not been detailed, leaving room for further study. Contextually, the fossil site is near a United Nations Chengjiang world natural heritage site known for other fossils.
This really is the first window we have into how basically the modern animal-dominated biosphere was formed and developed and came through this weird Ediacaran transitional interlude.
This proximity suggests the region holds rich paleontological potential, yet what environmental or ecological factors drove the transition from simple to complex animal life earlier than previously thought is still unknown. According to Dr Gaorong Li, the discovery closes a major gap in the earliest phases of animal diversification. Additionally, Frankie Dunn noted that this provides the first window into how the modern animal-dominated biosphere was formed and developed through the Ediacaran transitional interlude.
Ross Anderson, another study co-author at Oxford's Museum of Natural History, added that now researchers know what's making them because they have those fossils for the first time. However, whether there are other similar fossil sites that could provide further evidence of early complex animal life remains an open question, and how this discovery impacts the broader timeline of evolutionary history, including the origins of vertebrates, is still being assessed by researchers.
Now we know what's making them because we have those fossils for the first time.