GRACILITY IN TETRAPODS

["D.W.Naish" <dwn194@soton.ac.uk>]

I need some thoughts on a fairly simple issue, and thus start here with a
relatively simple question. Does anybody know of, or can they think of, any
mechanisms that might encourage the evolution of gracility in a lineage? Besides
the obvious speed-race theories. I am trying to find out if there is any
evidence suggesting that molecular, ontogenetic or phylogenetic factors can
create or exasperate such a change.

On the soft-part/molecular levels, evidence can obviously only pertain to extant
forms. Any hypothetical models might be applicable to dinosaurs, however. They
provide us with some of the best progressively-more-gracile lineages of all
time. As you'll know of course....

Many thanks for any thoughts, this is grossly applicable to dinosaurs I say
again!

DARREN 'parents now home' NAISH