mammals morphologically evoluated a lot since the Ceno zoïcum, invertebrates did not.Why?

[B.J.Tindall]

Dear Hans,
I would conclude that you mean that there is little (visible) morphological
change. However, at other levels there may well be comparable changes in
the gene or protein sequences which do not reuslt in visible changes in
morphology. Isn't this a topic which is the basis for the theory of "mode
and tempo" in evolution by G.G.Simpson - largely based on morphological
changes and the fossil record? Back in the 1970's A.C.Wilson also started
to link this topic to "biochemical evolution".
Brian

At 14:03 07.02.06 +0100, Hans Henderickx wrote:
>Dear colleagues,
>
>Especially based on amber fossils, it can be concluded that invertebrates
>did not evoluate significant since the early Cenozoïcum. They were other
>species, but very much alike the recent ones and often from the same genus.
>(Lourenço, Henderickx & Weitschat 2005 (scorpions), Vitali 2005
>(Coleoptera),  Heiß (Heteroptera). Francesco Vitali and I are discussing
>this paradox. The evolution of insects, pseudoscorpions and spiders is
>practically motionless for millions of years, and the ancient forms are
>often even more specialized (f.i. Pseudogarypus.) That is very different
>from the evolution of Mammalians. This fact is very strange because mammals
>are able to have only few generations each century. Hence, their evolution
>should be much slower than that of arthropods. Instead we are observing the
>contrary. Is it because mammals are a much more recent group and have not
>reached a stabilized status yet? Who can help us finding an explanation to
>this fact?
>
>Hans Henderickx
>


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