Pale, wormlike tubes in 890-million-year old rock may be ancient sea sponges, a new study concludes. If confirmed, that controversial claim would push back the origin of the earliest sponges by about 350 million years and make the tiny squiggles the oldest known fossils of animals, by far.
Crucially, these fossils would imply that animals emerged in environmental conditions previously thought unworkable for animal life, geologist Elizabeth Turner reports July 28 in Nature.
Early in Earth’s history, the ocean mostly lacked oxygen. It wasn’t until a large pulse of the gas to the atmosphere about 800 million to 540 million years ago, known as the Neoproterozoic Oxidation Event, brought
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