2-Billion-Year-Old Fossils May Be Earliest Known Multicellular Life

"A newly discovered group of 2.1 billion-year-old fossil organisms may be the earliest known example of complex life on Earth. They could help scientists understand not just when higher life forms evolved, but why.

The fossils — flat discs almost five inches across, with scalloped edges and radial slits — were either complex colonies of single-celled organisms, or early animals. Either way, they represent an early crossing of a critical evolutionary threshold, and suggest that the crossing...