Re: Perching

["John V Jackson" <jjackson@interalpha.co.uk>]

-----Original Message-----From: Stanley Friesen <sarima@ix.netcom.com>Date:
25 April 1998 08:41


>What I see in the smaller
>members of the basal coelurosaurs are animals adapted as scansorial - mixed
>arboreal and cursorial.  Such animals climb straight up all sorts of trunks
>as easily as they run along the ground.

Yes, I'm sure they were often like that, much more so than is often
appreciated.

>>  Maybe the ability to cling
>>to both a vertical large diameter trunk and a more horizontal small
>>twig is a very specialised late adaptation - even now, many birds
>>would find the former difficult,
>
>Actually, I would consider that a *loss* - due to the loss of claws on the
>hands (presumably for aerodynamic efficiency).

Yes - modern birds have lost the exact method by which eg _A_ did it, but
some have developed a new way of doing it using only the feet.

>On the other hand, at least some researchers have claimed that Archy's feet
>are *not* well suited to perching - due to a difference in the curvature.
>(The opposite has also been claimed, and I am not quite clear enough on the
>arguments to adequately judge who is right here).


Though there is uncertainty here over it's perching ability, I believe it
was perfectly adapted (with it's feet more squirrel-like than modern birds
for one thing) for scaling trunks and standing primate-like on horizontal
branches if it found them and running along bigger ones.  (And I still claim
that the the idea that _A_ has no obviously arboreal adaptations is possibly
the most ??? statement ever, palaeontologically speaking!)

JJ

By the way - Protoarchaeopteryx - tibiae big compared to arm bones?  Arms
longish but much shorter than legs?  That feather - pretty symmetrical?  Is
it just the one headless specimen?