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...and how ranks don't work was Re: Sauropodz r kewl



Am 18.04.2012 17:01, schrieb Anthony Docimo:

 We've demolished groups such as Pachyderma, relocating its members
 (rhinos, elephants, etc) to their true relatives...and yet the
 tuatara, aardvark and pangolin are set aside in their own groups with
 no near extant relatives. so, if there is no way to quantify it, why
 do we keep them separate?

Because we think in trees.

Rhynchocephalia and Squamata are sister-groups. To put *Sphenodon* (and the extinct rhynchocephalians) into Squamata would just mean we'd confuse everyone and need to come up with a new name for what we used to call Squamata. Note how I wrote this without mentioning a rank once.

As Mike Keesey explained, it works the same way for the aardvark and the pangolins.

> So the differences that make up the phyla represent 'huge'
> differences that accumulated over a long period of time, and
> therefore the phyla originated in the pre-Cambrian. Orders in the
> Cretaceous, etc. Again, not advocating that, but I think that's the
> idea behind it.

 ah, okay; yeah, that makes sense for things further away in deep
 time.

Only because the fossil record isn't any better. If it were, we'd run into the problem I just explained using birds.