Researchers have discovered an unusually rich fossil site in Canada’s Northwest Territories, pushing back the timeline for early animal movement and sexual reproduction by five to ten million years, according to a study published in Science Advances.
Discovering Ediacaran Fossils in the Mackenzie Mountains
The newly identified site in the Mackenzie Mountains contains fossils belonging to the Ediacaran biota, an assemblage of mostly soft-bodied organisms that inhabited ancient seafloors more than 500 million years ago. According to the study led by scientists at the American Museum of Natural History and Dartmouth, some specimens date back approximately 567 million years. Before this find, White Sea assemblage fossils had been documented in Europe, Asia, and Australia, but not previously in North America. The discovery sits on the traditional lands of the Sahtú Dene and Métis, whose communities provided the researchers with guidance and permission to study the region.
Unprecedented Diversity in North America
Scientists identified more than 100 fossils at the Canadian location, including six groups never before recorded in North America. The assemblage includes flat discs, leafy shapes, and ribbed ovals that represent some of the earliest multicellular animal life. Because these organisms lived before the common evolution of hard shells and bones, their soft tissues rarely survived the fossilization process without exceptional environmental conditions. According to Justin Strauss, an associate professor of Earth and Planetary Sciences at Dartmouth and co-author on the study who has explored the area for about 15 years, the site fills a critical gap in the rock succession where researchers previously lacked fossil remains.
Did You Know? Ediacaran organisms lived during a roughly 40-million-year period before skeletal hard parts became common. Sites containing more than 10 species from this era are exceptionally rare globally.
Ancient Seafloor Creatures and Early Behaviors
The recovered specimens reveal complex behaviors among Earth’s earliest large animals, including locomotion and sexual reproduction. Scott Evans, assistant curator of invertebrate paleontology at the American Museum of Natural History and lead author of the study, noted that life shifted rapidly from microbe-dominated ecosystems to large, complex marine animals capable of familiar behaviors. Among the notable specimens identified in the Mackenzie Mountains are several unique taxa:
- Dickinsonia: A flat, pancake- or bathmat-like animal that traveled across the seafloor, absorbing nutrients through its lower surface without a mouth.
- Funisia: A stationary, tube-shaped organism found in clusters, providing the oldest known fossil evidence of sexual reproduction through the coordinated release of gametes.
- Kimberella: An early relative of mollusks that moved using a muscular foot to scrape food, potentially representing the oldest known fossil bilaterian.
- Eoandromeda: A possible comb jelly featuring eight arms arranged in a spiral pattern.
Deep-Water Origins of Early Evolution
Position analysis of the fossils indicates that these organisms inhabited deeper water than researchers previously associated with the White Sea assemblage. According to Evans, this distribution supports the hypothesis that evolutionary innovation began in deeper marine environments before spreading toward shallower coastal waters, reversing the typical pattern seen in later animal evolution. The relative stability of the deep ocean, featuring minimal temperature and oxygen fluctuations, likely provided a favorable setting for early animal diversification.
Future Preservation and Research
The newly collected fossils will eventually join the permanent collection at the Prince of Wales Northern Heritage Centre in Yellowknife, Northwest Territories. With hundreds of feet of overlying rock still remaining to be fully explored at the site, researchers anticipate uncovering additional specimens. The study was supported by grants from NASA Exobiology (# 80NSSC25K7024), the U.S. National Science Foundation (# EAR-20 2143164), and NSF Frontier Research in Earth Science grants (# EAR-2021324 and EAR-2021176), with additional co-authors from Stanford University and The Pennsylvania State University.
Frequently Asked Questions
What are Ediacaran fossils?
Ediacaran fossils are the remains of mostly soft-bodied, multicellular organisms that lived on ancient seafloors more than 500 million years ago, representing the earliest direct record of complex animal life.
Why is the new Canadian fossil site significant?
The site in the Northwest Territories is the first White Sea assemblage location found in North America. It contains specimens dated to approximately 567 million years old, pushing back the timeline for early animal movement and sexual reproduction by five to ten million years.
Where will the fossils be housed permanently?
The fossils will become part of the permanent collection at the Prince of Wales Northern Heritage Centre in Yellowknife, Northwest Territories.
What are your thoughts on this discovery? Share your perspective in the comments below, or subscribe to our newsletter for ongoing updates on paleontology and Earth history.