570 Million Years Ago, Earth's Oldest Animals Formed Complex Ecological Communities

A new analysis is shedding light on the earth’s first macroscopic animals: the 570-million-year-old, enigmatic Ediacara biota.

Ediacaran fossils have a slightly bizarre appearance not shared by any modern animal groups. For decades, researchers believed these enigmatic fossils were ecologically simple. However, borrowing a method from modern ecology – fitting species to relative abundance distributions – Vanderbilt University paleontologist Simon A.F. Darroch and his team learned that these organisms were more like modern animals than once thought.

The analyses showed that a majority of fossil assemblages bear the hallmarks of being ecologically complex, and Ediacara biota were forming complex communities tens of millions of years before the Cambrian explosion. The creatures lived partially submerged in what was once the ocean floor, some of them suspension feeding, others filter feeding, still others passively absorbing nutrition. A few were even mobile.

Simon A.F. Darroch, assistant professor in the of Department of Earth & Environmental Sciences, doing field work in Namibia.