Tiktaalik: Fish-Tetrapod Transitional Fossil

A new transitional fossil between fish and tetrapods is described in today's Nature. It's called Tiktaalik roseae and from what I've read so far it is an interesting story. Back in 1999 the researchers specifically targeted a remote area of Canada based on geological information and hoped to find this type of fossil. It's a nice example of a prediction fulfilled in paleontology.

As Martin Brazeau, a graduate student in paleontology and blogger at The Lancelet said,

The key is that the object of the Daeschler and Shubin mission is very rare. To pinpoint where one might find such rare fossils, a lot of things have to go right: the age of the rock formation needs to be known (and correct). The type of environment it was deposited in needs to be correct. Marine-type sediments very rarely have tetrapods or their nearest relatives. Thirdly, your prediction based on the evolutionary sequence seen in the rest of the fossil record has to be accurate. In essence, multiple independent lines of historical evidence are being put to the test. Each one converges to pinpoint where the right fossils of the right type and age will be found.

The Lancelet has a two-part post: the setup and the description.

Pharyngula also has some analysis along with additional pictures and graphics.

Here is a news article from Nature.

Update: Carl Zimmer chimes in with an excellent post that puts this in historical context. Don't miss it. (Zimmer's book, At the Water's Edge, dealt with the sea-to-land transition.)

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