Re: paraphyletic Dromaeosauridae (Variraptor)

["Jaime A. Headden" <qilongia@yahoo.com>]

Ken Kinman (kinman@hotmail.com) wrote:

<Of course, some of this may be a rooting problem of some kind.  I can't 
help but wonder if their isn't some bias (in computer programs or deep in 
people's brains) to have smaller forms like Microraptor split off earlier
and larger forms then appear more derived by default.>

  I see it easier to have smaller forms start out with larger forms
developing later. This is how primates and mammals generally work,
lizards, snakes, etc. Typical forms are small, and get larger with
evolution. Just look at all the early 1900's work on brontotheres. 

  However, back to rooting, this isn't a problem. In these analyses, birds
were not the only taxa in the matrix, so were oviraptorosaurs and
troodonts and ornithomimes. To root a taxon in a cladistic matrix, you
have to explicitly tell it that taxon is the outgroup, and this is only
done if the group appears at the base or is not a member of the groups
studied to begin with. so a non-maniraptoran would be chose, e.g.,
ornithomimes, and the rest "fall as they may." It would be very unwise,
and unpracticed to my knowledge, for the taxa to be rooted on birds.


=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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