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

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.



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