Sunday, September 10, 2006

 

Meet your ancestor: Fish Tetrapod, Vertebrate 'Missing Link' (Tiktaalik roseae)

Frasnian Traits Panderichthys Acanthostega Tiktaalik roseae (Evolution Research: John Latter / Jorolat)

At first, Ted Daeschler thought the fossil was just a fragment of a lungfish snout - interesting, but not earth-shaking. He and his colleagues were after bigger quarry. They had come to Ellesmere Island, high in the Canadian Arctic, in search of the fish that first dragged itself out of water nearly 400 million years ago, the evolutionary forebear to all land vertebrates - and, as such, our own very distant ancestor.

Daeschler carefully packed up the fragment and set it aside to study another day. It sat for months in a drawer...

...That unassuming fragment of bone [subsequently] helped lead Daeschler and his colleagues, Neil Shubin of the University of Chicago and Farish Jenkins of Harvard University, to one of the most important fossil finds of the decade: several specimens of an almost perfect intermediate between fish and land vertebrates, or tetrapods. All are so beautifully preserved that the researchers could see almost every detail of their skeleton. The new creature, which they named Tiktaalik - from the Inuit name for a large, shallow-water fish - gives us a rare and vivid glimpse of how, and why, vertebrates took their first tentative steps toward land.

Other experts are ranking Tiktaalik roseae with some august company. "Everybody points to Archaeopteryx as a link between reptiles and birds," says Jennifer Clack, a palaeontologist at the University of Cambridge, referring to the iconic fossil found in all the textbooks... [Missing Link]
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The above feature article from New Scientist referes to two papers from the journal Nature:

"A Devonian tetrapod-like fish and the evolution of the tetrapod body plan" (Abstract)

"The pectoral fin of Tiktaalik roseae and the origin of the tetrapod limb" (Abstract)

An earlier news report contains a video link: "Fossil shows how fish made the leap to land"

Also see the Tiktaalik roseae website

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