Re: Feduccia's delusion

["Tim Williams" <tijawi@hotmail.com>]

David Marjanovic wrote:

>         In his 1999 second edition of his 1996 book, he writes (judging 
> from a review; I haven't read the book) that all similarities >between 
> Compsognathus and Archaeopteryx are due to convergence. Then he argues that 
> Compsognathus, like Sinosauropteryx, was an aquatic lake dweller, while 
> Archaeopteryx is totally arboreal!

Well put David.  This is the Achilles' heel of Feduccia's "convergent 
evolution" argument.  If you're going to argue that two groups are 
anatomically very similar because of convergent (or parallel) evolution, 
then you cannot claim in the same breath that the two groups also had highly 
divergent ecologies.  You can't have your cake, and eat it too.

> From 'The Origin and Evolution of Birds':
"Although it is relatively easy to uncover superficial whole-animal 
resemblance caused by convergence, such as the examples of birds just 
mentioned [e.g. great auks and penguins], or in vertebrates - fish and 
dolphins, and bats and pterosaurs - convergence is often so complete, so 
elusive and subtle, that clues can be difficult to ascertain.  One case of 
massive or whole-animal convergence is that of Mesozoic, toothed divers 
(_Hesperornis_) and modern loons..."

_Hesperornis_ looks like a loon presumably because it had a similar 
lifestyle as a foot-propelled diving bird.  (Statement of the Bleeding 
Obvious #1)

However, _Parahesperornis_ looks like _Hesperornis_ because it had a similar 
lifestyle AND because the two are closely related (SOTBO #2).  The 
similarities between small maniraptorans and _Archaeopteryx_ extend far 
beyond just overall morphology ("bauplan").  _Archaeopteryx_ and small 
maniraptorans share a long list of derived theropod characters in common, 
which is why cladistic analyses consistently come up with phylogenies that 
show _Archaeopteryx_ nesting comfortably inside the Maniraptora.



Tim

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