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Re: Mats and boles, relatively? (bipedism)

Not just vertebrate morphology: competition for height
led to the evolution of woody plants even before
vertebrates arrived on land.  Thus, an arena of
competition among vertebrates was ready and waiting
for them.  As speculation, this arena may have favored
endoskeletons over exoskeletons.

Glen Ledingham

--- don ohmes <d_ohmes@yahoo.com> wrote:

> If one views the biosphere through time, from zero
> hour to present, there is logically a point at which
> the only terrestrial vertebrates were effectively
> "sprawling quadruped(s)". It follows that the
> transition through vertical space from a condition
> of maximal vertebrate competition to minimal (i.e.,
> zero) vertebrate competition was abrupt, possibly
> mere centimeters, and any small advantage in
> vertical reach could make a huge difference in the
> probability of reproductive success. 
> This is an excellent reason for hauling one's self
> up on one's hind legs; or hauling one's self up a
> tree, or learning to fly, for that matter ... the
> advantage of vertical access has obviously been a
> huge driver of vertebrate morphology.
> Don
> [Sidebar -- I dimly remember reading a paper
> (published I think in the
> '60's) that explored this idea of an early land of
> milk and honey mere centimeters over your head, and
> it's effect on vertebrate evolution, but can't
> remember the author. Hell, I am not totally sure I
> read such a paper; does this concept ring a bell w/
> anyone, so I can get a re-read?]
> ----- Original Message ----
> From: "Dinogeorge@aol.com" <Dinogeorge@aol.com>
> To: VRTPALEO@usc.edu
> Cc: Dinogeorge@aol.com; george.olshevsky@gmail.com
> Sent: Saturday, November 17, 2007 10:48:33 PM
> Subject: Re: Bats and moles, relatives? (ptero
> launch)
> In a message dated 11/17/2007 6:19:04 P.M. Pacific
> Standard Time,  
> tijawi@yahoo.com writes:
> >>Another reason (much better supported) why birds
> never lost  their 
> hindlimbs as locomotor organs is because, as
> theropods, they are
>  descended  from 
> bipeds that came to use their forelimbs for aerial
> locomotion.  As
>   theropods 
> developed flight, their hindlimbs never deviated
> from their ancestral
>   function in 
> bipedal locomotion. <<  
> How did this  "ancestral biped" come into existence?
> What sequence of 
> selection events caused  a sprawling quadruped to
> haul itself up onto
>  its hind legs 
> and start walking and  running around?
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