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Re: Turtles and Crocodylians are not Reptiles - no? What are they?



On Sun, Jul 27, 2008 at 8:04 PM, Tim Williams
<twilliams_alpha@hotmail.com> wrote:
>
> True.  Again, Nick said the same thing, and I agree with it.  But I disagree 
> with the inference that this makes cetaceans *closer* to hippos than to 
> mesonychians.  Just because Mesonychia is outside the least inclusive clade 
> that contains whales and hippos does not necessarily make whales *closer* to 
> hippos.  To use an analogous example, _Deinonychus_ is outside the least 
> inclusive clade that contains _Archaeopteryx_ and _Passer_; but 
> _Archaeopteryx_ is still *closer* to _Deinonychus_ than it is to _Passer_.  
> (Phew, I finally managed to work in something to do with dinosaurs!)

Nick was obviously using "closer" in the sense of "sharing closer
common ancestry with". Of course, that's not the only possible use of
the word, but I think it was fairly clear in the context.

Speaking of possible uses, which metric *are* you using? Generational
distance? Chronological? Genetic? Morphological?
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