The discovery of leaf-thin, seaweed-like fossils in China nudges back the moment when ancient life went from microscopic to merely tiny. At 600 million years old, the new fossils—called the Lantian Formation—are 27 million years older than the so-called Avalon fossils found in Canada and England, which, until now, were the earliest known fossil assemblage of multicellular life. The new specimens, some resembling modern day seaweeds, represent 15 or so photosynthetic algae  researchers report online today in Nature. Unlike the Avalon fossil organisms, which thrived in deep-water environments, these ancient "seaweeds" lived in shallow marine seas. That means paleontologists need to rethink their theory that oxygenation of the deep oceans triggered the rise of more complex organisms.
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