These 567-Million-Year-Old Fossils Are Rewriting the Story of Life on Earth

Ancient deep-sea organisms suggest movement, sexual reproduction, and complex animal life began earlier than previously thought.

Every animal alive today, from jellyfish to humans, traces its ancestry back to a pivotal moment when complex life first emerged from a world dominated by simple microbes. Yet the fossil record from this evolutionary turning point remains frustratingly sparse, leaving major questions about when early animals first evolved key traits and how they spread across ancient oceans.

Researchers have uncovered an exceptionally rich fossil site in Canada’s Northwest Territories that could help fill some of those gaps. The fossils, belonging to the enigmatic Ediacaran biota, reveal that some hallmarks of animal life, including movement and sexual reproduction, may have evolved 5 to 10 million years earlier than previously recognized. The findings, published in Science Advances, were led by researchers at the American Museum of Natural History and Dartmouth.

“For 3 billion years, life on Earth was dominated by microbes. Then, all of a sudden, we get these strange-looking marine animals big enough to see and capable of behaviors we would find familiar today,” said the study’s lead author Scott Evans, assistant curator of invertebrate paleontology at the American Museum of Natural History. “If we want to understand this transition, when life first became large, complex, and unmistakably animal, this new site has tremendous potential.”

Fossils capture early animal complexity

Ediacaran fossils come in forms ranging from flat disks and leaf-like fronds to ribbed ovals. They provide the earliest direct fossil evidence for multicellular animal life.

Some Ediacaran species are connected to broad animal groups such as mollusks, nematodes, comb jellies, and cnidarians (a group that spans jellyfish and corals). Others have no clear modern equivalent, but they include the oldest animals known to move in search of food or reproduce sexually.

Because Ediacaran organisms lived before most animals evolved shells, bones or other hard body parts, they were usually soft-bodied. That makes their fossils difficult to preserve and rare to find. Although Ediacaran fossils have been discovered on every continent except Antarctica, only a small number of sites contain more than 10 species. Those rare places offer some of the best evidence from a crucial interval of about 40 million years in Earth’s history.

North America fills a gap

Scientists group Ediacaran life into three main assemblages that mark different periods in the fossil record: the Avalon assemblage (575-559 million years ago), the White Sea assemblage (559-550 million years ago), and the Nama assemblage (550-538 million years ago). Before this discovery, fossils from the White Sea assemblage had been found in Europe, Asia, and Australia, but not in North America.

In the new study, scientists identified clear White Sea assemblage fossils in ancient rocks of the Mackenzie Mountains in Canada, on the traditional lands of the Sahtú Dene and Métis, who guided the research group and gave permission to access the site.

The work builds on earlier geological studies in the area, but it marks a major advance. The scientists found more than 100 fossils, including six groups that had never before been recorded in North America. The most surprising result was their age. Some specimens are estimated to be about 567 million years old, making them 5 to 10 million years older than previously known White Sea fossils and placing them partly within the time of the older Avalon assemblage. The fossil layers also sit below hundreds of feet of rock that may contain more fossils.

“Not only is this new site highly diverse, but also it is from a part of the rock succession where we have previously lacked fossil remains,” said study co-author Justin Strauss, an associate professor of Earth and Planetary sciences from Dartmouth, who has been exploring this area for about 15 years. “This is really exciting. Given our understanding of the regional geology in northwestern Canada, there is great potential here to revisit our understanding of Ediacaran Earth history.”

Rare species extend key behaviors

Among the discoveries reported for the first time in North America are:

• Dickinsonia, a flat organism that moved across the sea floor. It had no mouth and instead absorbed bacteria and algae through its entire underside. Evans describes it as a “bathmat” or “pancake” with a divided circular body.
• Funisia, an immobile tubular organism that lived in clusters of similar sized individuals. It provides the oldest fossil evidence of sexual reproduction, likely involving the coordinated release of sperm and eggs into the water column, similar to corals.
• Kimberella, an organism with a muscular foot that fed by scraping the sea floor. It is widely interpreted as an early relative of mollusks and may now be the oldest known fossil bilaterian. Bilaterians are animals with a distinct front, back, top, and bottom, along with left-right symmetry, and they make up more than 99% of known animal species.
• Eoandromeda, a possible comb jelly with eight spiral arms.

Deep waters may have mattered

The scientists also found that these organisms lived in deeper water environments than had previously been recognized for the White Sea assemblage. The result supports the emerging idea that early animals may have first developed in offshore, deep marine settings before spreading into shallower water. That pattern runs counter to the more typical direction of animal evolution after this time.

“These results suggest a pattern where evolutionary innovation begins in deeper environments and later spreads toward the coast,” Evans said. “We think of the deep ocean as a dark, inhospitable place, but it is also relatively stable, with few fluctuations in things like temperature and oxygen essential to most animal life. This stability may have provided key opportunities to support early animal life.”

Reference: “Discovery of White Sea assemblage fossils from Laurentia” by Scott D. Evans, Erik A. Sperling, Kimberly V. Lau and Justin V. Strauss, 20 May 2026, Science Advances.
DOI: 10.1126/sciadv.aed9916

This work was supported by a NASA Exobiology grant (# 80NSSC25K7024); a U.S. National Science Foundation (NSF) grant (# EAR-20 2143164); and NSF Frontier Research in Earth Science grants (# EAR-2021324 EAR-2021176).

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