Paleontologists from the Australian National University have described a new species of ancient fish, after unearthing the largest fossilized lobe-finned fish skull ever found in rocks of Devonian period.
Life-size model of Edenopteron keithcrooki built by Baz Crook (Australian National University)
The paleontologists were excavating the skeleton of an extinct armored fish from 360 million-year-old rock near Eden, Australia, when the bones they uncovered suggested there was more in the site than met the eye.
“As we lifted out the block, we noticed a very large fang, at least 4 cm long,” said Dr Gavin Young. “Armored fish don’t have teeth, so we knew there must be a much larger predator also preserved at the site. We uncovered an almost complete skull and shoulder girdle of an enormous lobe-finned fish, with jaws about 48 cm long.”
The paleontologists used traditional methods of acid etching and casting, but also experimented with the latest surface scanning techniques to reconstruct the bones, and used high resolution CT scanner to investigate the internal structure of the teeth.
“We compared the shape and structure of the preserved bones with about 100 fossil fish species from elsewhere in the world. It turns out that we have not only a species new to science, but also a new genus of lobe-finned fish, which we have named Edenopteron after the town of Eden,” Dr Young said.
The new species, described in the journal PloS ONE, was named Edenopteron keithcrooki after Prof Keith Crook of the former Australian National University’s Geology Department.
“The discovery of this new species has implications for the classification of other Devonian lobe-finned fish,” Dr Young said. “This animal had some unusual features compared to Devonian fish fossils from the Northern Hemisphere, including extra bones in its palate, and strange ornamentation on the scales.”
When E. keithcrooki was alive, Australia and Antarctica were joined in the great southern supercontinent of Gondwana. “It’s pretty clear that we had an endemic lobe-finned fish group in this part of the world, and that has very interesting consequences for hypotheses of where the first land animals evolved,” Dr Young said.
The next step for the team is to continue excavating the site to see if the body of Edenopteron might be preserved deeper in the rock.
“That would be a massive excavation because it would be 2 to 3 m long, but would most definitely be an absolutely spectacular find,” Dr Young concluded.
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Bibliographic information: Young B et al. 2013. A Gigantic Sarcopterygian (Tetrapodomorph Lobe-Finned Fish) from the Upper Devonian of Gondwana (Eden, New South Wales, Australia). PLoS ONE 8 (3): e53871; doi: 10.1371/journal.pone.0053871
