August 18, 2011
Protoanguilla palau: 'first eel'. Photo by: Jiro Sakaue.
"The equivalent of this primitive eel, in fishes, has perhaps not been seen since the discovery of the coelacanth in the late 1930s," says Dave Johnson, ichthyologist at the Smithsonian's National Museum of Natural History and lead author of the team's research, in a press release. Before its discovery in the 1930s, the coelacanth was only known from fossils dating back 70 million years. However, even the eel fossil record has never shown anything quite like this.
The new species, named Protoanguilla palau, sports a second upper jaw bone and less than 90 vertebrate. These two features have only been seen in fossil eels going going to the Cretaceous. But another feature breaks all the rules: the animal has a complete set of 'rakers' in its gill arches, which has only been seen in bony fish, never before in eels either alive or fossilized. To determine its truly relationship to eels and bony fish, the researchers analyzed the animal's mitochondrial DNA and found that it is a 'true eel'. The animal likely appeared some 200 million years ago, just at the very end of the Triassic period.
"We believe that such a long, independent evolutionary history, [...] retention of several primitive anatomical features and apparently restricted distribution, warrant its recognition as a living fossil," says Johnson.
The eel's genus, Protoanguilla, created for this one species, means 'first eel'.
"The discovery of this extraordinary and beautiful new species of eel underscores how much more there is to learn about our planet," Johnson adds. "Furthermore, it brings home the critical importance of future conservation efforts—currently this species is known from only 10 specimens collected from a single cave in Palau."
CITATION: G. David Johnson, Hitoshi Ida, Jiro Sakaue, Tetsuya Sado, Takashi Asahida and Masaki Miya. A 'living fossil' eel (Anguilliformes: Protoanguillidae, fam nov) from an undersea cave in Palau. Philosophical Transactions of the Royal Society B, Aug.16, 2011.
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