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

[David Marjanovic <david.marjanovic@gmx.at>]

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.