Phys.org has a story about the origin of sharks. It has been thought that sharks had a more primitive beginning than other types of fish. This was due to their distinctive, all-cartilage skeleton. But now, a new fossil find from the Gogo in the Kimberly in Western Australia has revealed a surprise 'missing link' to earlier somewhat bony forms of fish. The original paper appeared in the journal PLOS One.
Published today in the scientific journal PLOS One, research by Flinders University palaeontologist Professor John Long substantially strengthens the theory that the modern shark is less primitive than previously believed.
In testing fossil remains discovered by Professor Long in July 2005 at Gogo in the Kimberley in Western Australia, detailed CT scanning analysis has shown that the three-dimensional remnant skeleton contains a small proportion of bone as well as cartilage.
Professor Long said the fossil, which dates from the Devonian Period (380 million years old), reveals an ancient shark caught in evolutionary transition.
Because sharks and rays have entirely cartilaginous skeletons, Professor Long said it was traditionally thought that they were part of a primitive evolutionary pathway, and that bone in other fish was the more advanced condition.
But a series of discoveries in recent years has suggested that sharks are "more evolutionarily derived", and are likely to be descended from bony ancestors.
