Missing Link In Shark Evolution Found
A 380m-year-old fossil found in Western Australia has revealed that sharks once had bone cells
The fossil found at the Gogo formation in Western Australia's Kimberly region shows that the ancient predator's skeleton was comprised of cartilage as well as bone cells, suggesting that sharks came from a less primitive evolutionary lineage than previously thought.
'That idea of shark evolution has been completely turned on its head,' palaeontologist John Long of Flinders University, who discovered the fossil, told The Guardian. 'Cartilage is seen as the precursor to bone, so sharks must be primitive because they never developed bone. This fossil suggests sharks went in the opposite direction because modern sharks lost bone.'
The find suggests that modern-day sharks have evolved from bonier fish and developed a cartilage skeleton making them a lighter, quicker and more successful predator.
'This is a big part of the puzzle when it comes to sharks. They appear 250m years before the last dinosaur and they haven’t changed much in that time, they’ve hit a winning formula. But while there hasn’t been much change in their appearances, there have been lots of subtle changes in their tissues.,' Long said.
Long, who already found the shark fossil in 2005, published his findings in the scientific journal PLOS One last month.