Thin layers of sediment point to early arrival of life on land

Thin layers of sediment point to early arrival of life on land

by Kristin Strommer, Museum of Natural and Cultural History, University of Oregon

New clues emerging from fossils found in the oldest soils on Earth suggest that multicellular, land-dwelling organisms possibly emerged much earlier than thought.

The evidence for such a conclusion emerged from fossil assemblages, previously considered to be ocean organisms, found in thin layers of silt and sand located between thicker sandstone beds in South Australia. The sediments date to between 542 million to 635 million years ago – during a geological period known as the Ediacaran.

“These Ediacaran organisms are one of the enduring mysteries of the fossil record,” said Greg Retallack, fossil collections director at the University of Oregon’s Museum of Natural and Cultural History. “Were they worms, sea jellies, sea pens, amoebae, algae? They are notoriously difficult to classify, but conventional wisdom has long held that they were marine organisms.”

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