Early animals might have caused a mass extinction event, says new evidence

New fossils discovered in the southwest African country of Namibia reinforce a theory that Earth's first mass extinction was caused by the planet's earliest animals, known as metazoans. These animals, which comprise most common forms of life today including vertebrates and arthropods, arrived on the scene roughly 540 million years ago. The effects of the diversification and spread of animals across the globe is known as the Cambrian explosion, and scientists now think it may have also led to the extinction of Earth's first multicellular organisms, known as Ediacarans.

"These new species were 'ecological engineers' who changed the environment in ways that made it more and more difficult for the Ediacarans to survive," said Simon Darroch,...