540-Million-Year-Old Fossils Reveal a Huge Surprise About Early Life on Earth

A Brazilian fossil study reclassifies 540-million-year-old “animal traces” from the Tamengo Formation as microbial communities, not tiny seafloor animals.

Researchers found preserved cellular structures and organic material consistent with fossilized bacteria or algae.

The reinterpretation pushes back against earlier claims about early meiofauna and shifts the timeline for animal evolution.

The findings support the idea that low oxygen levels in Ediacaran oceans may have limited complex life before the Cambrian explosion.