Re: secondary flightlessness

[david.lessin@walgreens.com]

>I agree. Preservational bias would tend to work against exactly the
 >sort of small, delicate arboreal forms that might have formed such
 >transitional forms". I have always been a punctuated equilibrium
 >person myself. Something is either well adapted to what it does or
 >it doesn't exists. The term "transitional form" tends to suggest some 
 >sort of directionality, being somewhere between one state and another,
 >which to me at least smacks of creationism (sorry Mickey - the dreaded
 >C word). I can't see the usefulness of being sort of able to fly and
 >sort of not. Hence my belief that such evolutionary leaps are rapid
 >( geologically speaking of course). Natural selection doesn't grant
 >pardons because a species swears that, in a few million years more,
> it will be really well adapted to a new niche.  :)

I would naturally agree with the statement that preservational bias is going 
lessen the odds of finding a smaller, more delicate, arboreal form, however...I 
think it is important to realize that "transitional form" is human convention 
and should only be applied to a fossil in that context. There are no 
"transitional forms" in nature, only those  organisms, genotypically and 
phenotypically suited for the environment in which it lives, and those which 
are not.  "Transitional Form" is a semantic artifice, that  we can use in lieu 
of the simple phrase " I do not know," or "I do not have enough data to answer 
that yet," etc..."transitional form" is also based on at least one working 
hypothesis. The "transitional form" that Greg is looking for, undoubtedly 
differs from the one that Alan is looking for. Selectional pressures do not 
grant pardons, and for that reason alone, the fossil record is more likely to 
produce an organism that is at least adequately adapted to its environment, if 
not greatly adapted.


_Dave Lessin