567-Million-Year-Old Fossils Rewrite the Dawn of Animal Life

Researchers have discovered an unusually rich fossil site in a remote region of Canada's Northwest Territories, revealing new details about some of the earliest complex animals on Earth. The fossils belong to the Ediacaran biota, a collection of mostly soft-bodied organisms that lived on ancient seafloors more than 500 million years ago.

Some specimens appear to be about 567 million years old. Their age suggests that animal movement and sexual reproduction began 5–10 million years earlier than previous evidence indicated. The study, led by scientists at the American Museum of Natural History and Dartmouth, was published in Science Advances.

Ediacaran organisms came in many unfamiliar forms, including flat discs, leafy shapes, and ribbed ovals. Their fossils provide the earliest direct record of multicellular animal life. Some Ediacaran species have been connected to animal groups that still exist, including mollusks, nematodes, comb jellies, and cnidarians. Other species resemble nothing alive today.

Scientists identified more than 100 fossils at the site, including six groups that had never previously been recorded in North America. Among the remarkable finds were Dickinsonia, a flat animal that traveled across the seafloor absorbing nutrients; Funisia, a tube-shaped organism providing the oldest known fossil evidence of sexual reproduction; and Kimberella, an early relative of mollusks that moved with a muscular foot and scraped food from the seafloor.

The fossils indicate that these organisms lived in deeper water than scientists had previously associated with this period. This supports a developing idea that early animals may have first appeared in offshore, deep marine environments before gradually spreading into shallower coastal waters — the reverse of what became more common in later animal evolution.

The stable conditions of the deep ocean may have offered a favorable setting for the earliest stages of animal diversification, providing key opportunities to support early animal life when temperature and oxygen levels fluctuated less than in shallow waters.