Tiny spheroidal fossils from a formation in South China provide insights into the early evolutionary history of complex multicellular life, according to scientists from Virginia Tech and the Chinese Academy of Sciences. While the exact identity and affinities of these 600 million-year-old fossils remains unclear, there is evidence that they are multicellular organisms with differentiated cells.
Dubbed Megasphaera, the fossils were found in the Doushantuo Formation, located in China’s Guizhou Province. 600 million years ago, the area was a shallow marine environment. Megasphaera measure only about 0.3 inches (0.7 millimeters) in diameter, but what has piqued scientific interest is that their constituent cells are different from each other.
The reason this is important is that differentiated cells generally have differentiated functions, suggesting that these organisms, whatever they were, had already reached an important evolutionary threshold of multicellular complexity. It still remains unclear precisely what the Megasphaera organisms were, but the two leading explanations are that they represent either very early animals or complex algae.