Re: New Ichthyostega reconstruction (Nature)

[David Marjanovic <david.marjanovic@gmx.at>]

> 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"