A Duke University press release notes the discovery of a large (1 inch diameter) marine amoeba that moves slowly and leaves distinctive tracks behind.
The distinctive trail that the Gromias leave is identical to mud tracks found in the fossil record, which throws a big wrench into one long-standing argument in biology. The fossil tracks pre-date the so-called “Cambrian explosion” 530 million years ago, which was a blossoming of multicellular life and complex body plans from what had previously just been simple, blobby life forms. Many paleontologists and evolutionary biologists have argued that such a trail couldn’t possibly have been made by a simple organism, meaning complex body plans were around before the Cambrian explosion. But the Gromia show that simple blobs can indeed move and make tracks in the light, silty bottom.
We’re confident that drawing attention to these bizarre mega-protists will provide a powerful new spin to the debate,” said biologist Mikhail Matz of the University of Texas at Austin, who is first author on the paper in Current Biology. Matz worked out the genetics of the new creature and found it’s a giant amoeba closely related to similar blobs found in the Gulf of Oman, near Antarctica, off Guam, and in the Mediterranean. None of them are known to move.