Re: Prolacertiformes and Protorosauria

[Mike Habib <habib@jhmi.edu>]

David Peters wrote:

> Once again, if sister taxa don't bear a family resemblance, you have  
> to doubt the results.

Wait - I'm confused: don't the sister taxa bear "family resemblance"  
*by definition*?  The tree constructs the best estimate of ancestry,  
using some kind of estimate of family resemblance.  For morphological  
character sets, this usually means using a parsimony algorithm, with  
is optimizing the distribution of characters and using synapomorphies  
to define clades.  Since you're joining taxa using shared derived  
character states, they *must* bear resemblance.  The fact that those  
taxa may have some kind of qualitative or intuitive lack of  
"resemblance" doesn't mean you screwed up.


> I added breaks at nodes that did either had closer excluded sisters  
> or just plain did not make sense. Without an overall understanding  
> of amniote relations, studies such as this one, undertaking such a  
> huge gamut with too few real sisters will bear little real results.

How do you determine which groupings make sense - isn't that the point  
of constructing the tree in the first place?  What's a "real sister"?

Cheers,

--Mike



Michael Habib, M.S.
PhD. Candidate
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280-0181
habib@jhmi.edu