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Re: DINOSAUR BEHAVIOR



At 02:24 PM 2/23/97 -0600, Joe Daniel wrote:
>Generally, drawing a link between an adaptation and its function is a
>pretty good idea.
        Of course, but overemphasis on funcitonality to the exclusion of
other considerations leads to inflexible thinking.  If we wish to understand
an adaptation, we must look at the path along which it developed, not merely
the end result.
        Sorry, I'm not making myself as clear as I should.
        :)

>Your comment was exactly my point.  I said that
>arboreality was not the prime reason for the big claw.  Their regular
        It is certainly not the reason that the claw became huge and
recurved, but might explain the initial isolation of the organ from the
cursorial locomotor apparatus.

>claws would work, they didn't need a special claw.
        Arboreal primates don't necessarily need prehensile tails either,
but some have them.  If a "peton claw" conferred an advantage, it might be
selected for, even if it was not necessarily a part of the arboreal
theropod's "minimum kit".

>If the claw became secondarily adapted for hunting, then it is no longer a
>specific adaption for arboreality which was the point I was trying to make.
        Certainly no arguments here.

>The claw was not an adaptaion for climbing as seemed to be the idea
        It *could* have been an exaptation of an adaptation for climbing,
however, which I would guess was the point of the post to which you were
responding (I beg forgiveness, I can't go burrowing for the post you were
responding to right now...).

>Huh?  No, I don't think our feet were evolved for climbing.  This is
>pretty obvious.  Humans are not arboreal.  We can use our feet for
>climbing but we aren't very good at it.  So, what was your point? 
        We went through an arboreal stage.  Our feet were wide with longer
digits, adapted for grasping branches and skittering about trees.  At least,
that's how I learned it.  They are secondarily reduced and strengthened for
a ground-bound existance.  Our feet show evidence of this transition, just
as one might construe the sickle claw as showing evidence of being used as a
climbing peton.  My point was, as I'm positive that you know, was that you
can't just take a trait and say "it must have evolved for it's current use".
        This is the gaff I believe Feduccia makes when he insists that
feathers evolved for flight (apart from some flaws in the logic of his
argument).  He cannot see what so many others have seen so often in the
fossil record, the exaption of a structure to a function different from it's
origional purpose (yup, that's redundant...).

>far as I know, no one has seriously considered monkeys as branching off
>from ground dwelling hominids.
        Of course not.  The natural conclusion then being that we exapted
our dogs from the foot morphology of other primates.

        Does it occur to you that we're arguing from two sides of the same
point?  :)

        Wagner

"That boy just ain't right..."
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| Jonathan R. Wagner                    "You can clade if you want to,     |
| Department of Geosciences              You can leave your friends behind |
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|       *** wagner@ttu.edu ***           Then they're no friends of mine." |
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