Northwest University Confirms 38 Fossils Place Bryozoans in Cambrian, Solving 500-Million-Year Gap
Updated
Updated · ScienceAlert · Jun 12
Northwest University Confirms 38 Fossils Place Bryozoans in Cambrian, Solving 500-Million-Year Gap
3 articles · Updated · ScienceAlert · Jun 12
Summary
Thirty-eight exceptionally preserved fossils from southern Shaanxi let researchers confirm bryozoans existed during the Cambrian explosion, closing a 500-million-year gap in the animal fossil record.
Microscopic imaging revealed soft tissues including muscle fibers and membrane sacs inside honeycomb-like colonies, allowing the team to identify two species—Protomelission gatehousei and the new Dayingomelission hexaclitia—as true bryozoans.
That evidence also settles debate over whether P. gatehousei was algae and suggests these fossils were already relatively advanced colonial forms, pushing bryozoan origins even earlier than the Cambrian.
The Nature study resolves one of Cambrian paleontology's longest-standing anomalies: every other major animal phylum already had Cambrian representatives, while bryozoans had previously appeared only in Ordovician fossils about 50 million years later.
If 520-million-year-old fossils were already advanced, what does this imply about life before the Cambrian explosion?
How did an animal's soft tissues survive for half a billion years, and what other evolutionary secrets can be found?
500-Million-Year-Old Bryozoans Found: Closing the Cambrian Fossil Gap and Rewriting Animal Evolution
Overview
On June 12, 2026, researchers made a major discovery that shed new light on the early evolution of bryozoans. By performing detailed microscopic imaging and analyzing intricate features like muscle fibers and membrane sacs preserved in ancient fossils, they successfully identified two distinct bryozoan species: the previously known Protomelission gatehousei and a newly described Dayingomelission hexaclitia. This thorough analysis definitively classified these species as bryozoans, resolving a long-standing debate about Protomelission gatehousei’s identity. The findings have broader implications, offering important insights into the evolutionary history of bryozoans and their early development.