Sunday, 4 January 2015

Ichthyostega and the first tetrapods

Reconstruction of Ichthyostega by Dr. Günter Bechly Stuttgart (CC)
Recently I visited the Zoological Museum in Copenhagen to see its new exhibition "Precious Things." On show is the skull of Ichthyostega, a fossil from Northeast Greenland that caused quite a stir when discovered in 1932. It was hailed as the missing link between fishes and land vertebrates, an early tetrapod.

Reconstruction of the Copenhagen skull of Ichthyostega
Wikimedia Commons uploaded by FunkMunk (CC)
Current research suggests Ichthyostega would have spent most of its time in the water, perhaps hauling itself up on to land to bask in the sun. It did not have the skeletal adaptations required for walking (here).

More recently discovered fossils such as Tiktaalik from Ellesmere Island offer better clues about the transition from water to land (here) but Ichthyostega has not yet lost its iconic status.

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