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Re: BADD BCF



In a message dated 95-12-07 16:20:42 EST, ornstn@inforamp.net (Ronald
Orenstein) writes:

>If you are talking about lifestyle, then you must, I think, to have BCF say
>anything new, separate adaptations to arboreality from adaptations to flight
>and show that the LATTER are present in forms usually regarded as derived
>from non-volant ancestors.  Which brings me back to the point above - are
>you really talking about anything other than the evolution of a few
>terrestrial taxa you see as secondarily flightless?  If so, then except for
>these few taxa (which, if I am not mistaken, all postdate Archaeopteryx so
>cannot be, in themselves, bird  ancestors), BCF and BADD are not just in
>agreement, they are phylogenetically identical - and therefore identical
>with respect to the origin of birds.  The question then becomes not what did
>birds evolve from, but what did post-Archaeopteryx terrestial maniraptors
>evolve from.

In BCF, flight--not powered flight but some kind of forelimb-controlled
gliding flight--comes much earlier in the phylogeny than in BADD, maybe as
early as the Middle Triassic. The phylogenies have always been in substantial
agreement--how could they not be? The characters are there in the terminal
taxa for all to see. It is the _interpretation_ of these features--why they
appeared--that differ between the two scenarios.