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Re: New Ichthyostega reconstruction (Nature)



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

"[...] _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."

GAH! And this shortly after the same people found out that *I.* did have internal gills, plus a unique middle ear* adapted for hearing in water!


The Editor's Summary** says lateral movement was practically impossible, and describes a movement that evokes a seal (especially if I assume *I.* is still thought incapable of putting its hindfeet on the ground).

* The plesiomorphic condition, retained by salamanders and caecilians, is not to have a middle ear at all.

** Here in my "apartment" ( = room) I don't have access to Nature. Will have to wait for tomorrow.

On another note...

"This week marks a landmark in the study of our closest living relative: the publication by the Chimpanzee Sequencing and Analysis Consortium of the initial sequence of the chimpanzee genome, together with a comparison with the human genome. The paper describes changes that have shaped human and chimpanzee species since the split from our common ancestor, and hints at what makes us uniquely human: 35 million single-nucleotide substitutions, 5 million small insertions and deletions, local rearrangements and a chromosome fusion."

"The final research paper in this collection fills a big gap in our knowledge: the first chimpanzee fossils ever found show that chimps and early humans inhabited the same environments in which they evolved and diverged. The fossils -- three teeth -- are from half-million-year-old sediments in Kenya that also yielded fossils of *Homo*."

-- Editor's summary of "The chimpanzee genome"