Twin-Nested Heirarchy

Have those studies been confirmed? It is a very surprising result: it has long been believed that the split between anapsids (turtles) and diapsids (the other reptiles) occurred very, very early.Color me skeptical, at least until further studies confirm this one.Added by edit:I should add the classical phylogenic tree from Palaeos. It shows the split between anapsids and diapsids occurring very early in the reptile lineage -- not long after the split between reptiles and synapsids (mammal ancestors) in fact. In fact, if I recall, it was debated for a short time whether the synapsids or the anapsids were the first to split from the main amniote line.Of course, our understanding of the evolution of any taxon is subject to change as new information comes to light. I was just under the impression that the classical understanding of the diapsid/anapsid split was pretty well established by palaeontology.Edited by Chiroptera, : No reason given.

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Computers have cut-and-paste functions. So does right-wing historical memory. -- Rick Perlstein

I just looked at mark's post, the one that started this: Since most people think that the synapsids (mammals) split from the diapsids/anapsids (birds and tortoises) before anapsids and diapsids split, then marks point is valid: we would expect that warm-blooded birds would share more molecular similarities to cold-blooded tortoises than to warm-blooded mammals.

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Computers have cut-and-paste functions. So does right-wing historical memory. -- Rick Perlstein