Thursday, September 4, 2014

New enigma

Way back in 1986, researchers from the University of Copenhagen collected organisms at 400 and 1000 meters depth on the south-east Australian continental slope. Only just recently they were able to isolate two types of mushroom-shaped organisms that they couldn't assign to any existing phylum.

These new organisms are multicellular and mostly non-symmetrical, with a dense layer of gelatinous material between the outer skin cell and inner stomach cell layers. The organisms were classified as two new species in a new genus, Dendrogramma enigmatica and Dendrogramma discoides, in the new family, Dendrogrammatidae. The researchers found similarities between the organisms and members of Ctenophora and Cnidaria suggesting that they may be related to either of these phyla. However, they also found similarities to the 600 million year-old and extinct Ediacara fauna.

The Ediacara fauna consisted of enigmatic tubular and frond-shaped, often sessile organisms which lived during the Ediacaran Period (ca. 635–542 MYA). The first Ediacaran fossils were discovered here in Canada in rocks around Newfoundland. In the BBC documentary First Life, Richard Attenborough shows some of the finds (about 23:16 in, but by all means watch the entire episode if you haven't already):

Many scientists belief that these Pre-Cambrian life forms represent early but failed attempts at multi-cellular life. If the authors of the new study were true this might shine some new light on those theories.

Unfortunately, the authors originally preserved the specimens in neutral formaldehyde and stored them in 80% ethanol, which makes them unsuitable for molecular analysis. Who can blame them for that as back in the 1980s nobody did molecular work on an ongoing basis. However, they suggest attempting to secure new samples for further study, which may provide further insight into their relationship to other organisms and perhaps the true status of the Ediacara fauna.

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