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Re: polarity of bipedality in dinosaurs (real long--TOO long)



Jeffrey Martz wrote:

>      I'm not sure that bats and pterosaurs are valid comparisons. <snip>
>      However,it is my impression that in mass reduction in this way would be
> more likely served by shrinking all digits down equally, rather than just by
> lopping off a couple digits. Pterosaurs and bats reduced ALL of the digits
> that weren't being used for flight equally (I think).   <snip>
>      If "dino-birds" were going to retain claws for climbing, might not a
> bunch of short, clawed fingers (like squirrils have, or like pterosaurs might
> have used for climbing) be better than a couple long clawed fingers(on the
> other hand, this raises the question of what a terrestrial
> bipedal theropod might find more handy about fewer, longer fingers)

I just wanted to interject that some bats have a specially developed
'thumb' on the wing wherein (I get to use the word 'wherein', hah!)
the thumb has re-formed into a disk so that the bat can use it as a
wedge to better grip loose tree bark.  I believe the claw on this
digit is lost completely.  Therefore the analogy that all digits on
bats except the ones used in the wing-flying membrane itself are
shrunk down equally is incorrect, because these disk-winged bats have
a specially adapted thumb, that serves a function on the wing other
than flight and nose-scratching.  So your pterasaurs or early birds
might also have other functions to their wings and the remaining
digits of the wing are not necessarily vestigal.

-Betty