Talk:Polyphyly
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This is a nice image, but I don't think it actually describes a polyphyletic group. The common ancestor of amphibians and mammals was a land vertebrate, and although the illustration does not show this, the lower land vertebrates are usually meant to include it. As such, this is a paraphyletic group, comprising all its descendants except the mammals (and I would think the birds). Might a better illustration might be the warm-blooded animals, highlighting Mammalia and Aves separately? Josh
Well, are you sure that the warm-blooded animals are a polyphyletic group? Was the most recent common ancestor of birds and mammals warm-blooded or cold-blooded? I think this picture actually shows a paraphyletic group, doesn't it? Because the yellow curve includes the fork between Mammaila and Aves? I don't know, I'm no biologist. Keenan Pepper 19:50, 21 July 2005 (UTC)
I'm not sure what to make of that picture. It's generally understood that the ancestral amniotes were cold-blooded, and crocodylians are too. Also, although it technically falls under the definition we give for paraphyletic, that group would still be polyphyletic since it leaves out connecting forms - the difference is whether the tree is topologically connected. I'm not entirely sure how to word this. Josh
How about this text? A picture highlighting mammals and birds separately would go great with it. Keenan Pepper 23:12, 22 July 2005 (UTC)
That sounds fair. The image would be easy to adapt, but it's on the commons and I don't know where the update should go. Josh
