New Ichthyostega reconstruction (Nature)

[Tim Williams <twilliams_alpha@hotmail.com>]

Ahlberg, P.E., Clack, J.A. and Blom, H. (2005).  The axial skeleton of the 
Devonian tetrapod _Ichthyostega_.  Nature 437: 137-140.

Abstract.  "_Ichthyostega_ was the first Devonian tetrapod to be subject to 
a whole-body reconstruction1, 2, 3.  It remains, together with 
_Acanthostega_4, one of only two Devonian tetrapods for which near-complete 
postcranial material is available.  It is thus crucially important for our 
understanding of the earliest stages of tetrapod evolution and 
terrestrialization.  Here we show a new reconstruction of _Ichthyostega_ 
based on extensive re-examination of original material and augmented by 
recently collected specimens.  Our reconstruction differs substantially from 
those previously published and reveals hitherto unrecognized regionalization 
in the vertebral column.  _Ichthyostega_ is the earliest vertebrate to show 
obvious adaptations for non-swimming locomotion.  Uniquely among early 
tetrapods, the presacral vertebral column shows pronounced regionalization 
of neural arch morphology, suggesting that it was adapted for dorsoventral 
rather than lateral flexion."