Re: Livezey and Zusi's big bird morph analysis [...]

[Tim Williams <twilliams_alpha@hotmail.com>]

Evelyn Sobielski wrote:

> But the case for convergence confounding analyses has
> been made, time and again, for exactly this clade. It
> is THE showcase example where parsimony is likely to
> run into a wall*, and has been since more than a
> decade (in fact, try doi:10.1007/BF01908745). This
> cannot be dismissed out of hand. Basically they
> reiterate a cold case; this is not good.

But why do you assume that the morphological characters shared by grebes and 
loons *are* due to convergence?  I agree with David here.  When it comes to 
assessing relationships between grebes and loons, why is the 
convergence/homoplasy hypothesis better supported than the common ancestry 
hypothesis?  Why can't the characters associated with foot-propelled diving 
also be potential synapomorphies?

This issue also comes up with plotopterids and penguins w.r.t. subaquatic 
diving characters; with birds of prey (traditional falconiforms and 
strigiforms) w.r.t. to predatory characters; with theropods and herrerasaurs 
too w.r.t. predatory characters; with euhelopodids and mamenchisaurs w.r.t. 
neck elongation; with dinosaurs and pterosaurs w.r.t. bipedalism...  And so 
on.

Cheers

Tim

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