Overview

• An MIT-led study in PNAS reports detection of C30 and C31 sterane biomarkers in Ediacaran-age rocks.
• Samples were analyzed from eastern Siberia, the southern Oman salt basin, and India’s Bikaner-Nagaur basin, all older than 541 million years.
• The steranes are interpreted as chemical fossils of demosponge ancestors, indicating sponge-like animals among Earth’s earliest fauna.
• Researchers present three complementary lines of evidence to argue the molecules were produced by organisms rather than abiotic processes or contamination.
• The authors note unresolved questions about organismal form and precise ages and plan broader global sampling to refine the timeline.