Gromia sphaericaThe BBC has this report on an interesting marine biology discovery, relevant to explaining trace fossils.  Unfortunately it’s a bit vague (exemplified by its title – ‘Grape’ is key to fossil puzzle), and doesn’t have a link to the original research paper in Current Biology. Personally, I think it looks less like a grape and more like a truffle.  The picture to the left shows a cleaned up example – the real things roll around the sea floor covered in mud.

Greg Laden’s Blog – Giant Gromia (amoebas) may account for ancient sea floor tracks presents a rather more coherent account of the paper, and includes a citation.  Unfortunately my university doesn’t have an online subscription to Current Biology.  Rats! Rats!

Another ScienceBlogs article, on Mike the Mad Biologist, Gromia sphaerica: It’s a Cool…Macrobe? has a little more, but focusses on the Discovery News article.  Mike observes that there is actually a frog species that’s smaller than this single-celled organism!

Why the excitement?  Well,  trace fossils are fossilised remains of animal activity – e.g., movement traces, burrowing, etc, and had always been thought to depend on presence of a bilaterally symmetrical (or, I suppose, radially symmetrical such as an echinoderm) metazoan animal.  The research team from the University of Texas (Austin) found these big protists sort of roll around and in time leave tracks very similar to those found dating from the pre-Cambrian era, well over 500 million years ago.  These trace fossils look like they are due to worm activity, but of course no corresponding fossils could be found, and they probably pre-date bilaterally symmetrical metazoans.

Unable to get my mitts on a pdf of the paper, I can’t really review it in detail.  Those of you more fortunate than I can get to it via this citation:

M Matz, T Frank, N MAarshall, E Widder, S Johnsen (2008). Giant Deep-Sea Protist Produces Bilaterian-like Traces Current Biology DOI: 10.1016/j.cub.2008.10.028