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The Radio weblog of Hal Rager

Wednesday, July 3, 2002

Fishy fossil reveals first steps on land A four-legged fossil from Scotland is finally shedding light on the mystery of how animals first crawled onto land. "The new creature, a type of tetrapod, is the only intact skeleton from this time period ever unearthed. It resembles an ungainly crocodile with a whip-like tail and the three-foot long amphibian had the sensory apparatus of a fish, but limbs and feet adapted for life on solid ground. The unique fossil is around 345 million years old and has been dubbed Pederpes, meaning rock crawler. "It's by far the earliest leg that looks like it could have been used on land," says Jennifer Clack of the University Museum of Zoology in Cambridge UK, who reports the discovery Nature. Previously, only a few fragments of tetrapod legs and shoulders had been found in Canada from this time gap. Before the gap, tetrapods had evolved limbs for paddling, but not walking. Immediately after the gap, they were running all over the land. (...) The discovery was a stroke of luck, says Clack. The fossil was collected in 1971. But it was misidentified as a type of fish called a rhizodont and the fossil was relegated to the basement of the Hunterian Museum in Glasgow. It lay there for 25 years until one of Clack's graduate students picked it up while trawling for rhizodonts for his dissertation work. When he brought it back to Cambridge, Clack saw immediately that it was in fact an early tetrapod. "When we combined it with the date, it was like finding the Holy Grail," she says." Journal reference: Nature (vol 418, p 72) [New Scientist] 7:10:46 PM    comment   trackback []