Sharks have a distinctive, all-软骨 skeleton, but now a fossil from Western Australia has revealed a surprise ‘missing link’ to an earlier, more bony form of the fish.
Published today in the scientific journal 公共科学图书馆一个, re搜索 通过 Flinders University palaeontologist 约翰·朗教授 substantially strengthens the theory that the modern shark is less primitive than previously believed.
Professor Long said the fossil, which dates from the 泥盆纪时期 (380 million years old), reveals an ancient shark caught in 演化ary transition.
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But a series of discoveries in recent years has suggested that sharks are “more 演化arily derived”, and are likely to be descended from bony ancestors.
“Our shark more or less nails that theory, because here we have a heavily mineralised type of 软骨 in the skeleton, which contains remnant bone cells,” Professor Long said.
Professor Long said the re搜索 indicates a direction in their 演化 that shows that sharks to be much more specialised than previously thought.
The Gogo formation, which is the remains of a tropical reef now located far inland, has proved to be one of the most important sources of Devonian fossil fish in the world.
“This is a really interesting discovery,” said 每阿尔伯格教授, a palaeontologist at Uppsala University in Sweden, which was not involved in the study.
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The find also represented a breakthrough in that it was the first specimen of a shark discovered at the Gogo site in 60 years of investigation.
“It means that we can go back and find more sharks with continued collecting,” said Professor Long, who will head back to the site later this year.