'Missing
link' in shark evolution found in 380m-year-old Australian fossil
Fossilised skeleton found in Kimberley shows sharks
once had bone cells within cartilage, suggesting a sophisticated evolutionary
path.A 380m-year-old fossil found in Western Australia
has been hailed as the “missing link” in shark evolution, revealing the marine
predator has a far more sophisticated lineage than previously thought.The
fossilised skeleton, jaws and teeth, found at the Gogo formation in the
Kimberley region of WA, shows the ancient shark had a small amount of bone as
well as cartilage.As modern-day sharks have fully cartilage skeletons, the
fossil suggests they evolved from an earlier, bonier fish, transforming to a
cartilage skeleton to make them lighter, more nimble and quicker through the
water.It was previously thought that sharks came from a primitive lineage that
didn’t ever develop bone, unlike other fish.
“That idea of shark evolution has been completely turned on its head,” said
palaeontologist John Long of Flinders University, who discovered the fossil.
“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.”
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