Scientists have determined that structures once seen as traces of tiny animals in 540-million-year-old Brazilian rocks are actually fossilized communities of bacteria and algae. The reexamination uses advanced imaging to reveal preserved cells and organic material.
Researchers focused on microfossils from the Tamengo formation in Mato Grosso do Sul. Earlier work had interpreted the marks as evidence of wormlike creatures moving through seafloor sediment during the Ediacaran period, just before the Cambrian explosion of complex life. New analysis with microtomography and Raman spectroscopy at the Sirius particle accelerator showed cellular structures instead of animal trails.