Re: early birds, etc.

[rowe (Mickey Rowe)]

Ronald Orenstein, one of our subscribers, is having difficulty with
mail routing from his machine, so I'm sending out the following
message for him.  My address will be in the Reply-to: line.  If you
wish to send mail only to Ronald, please edit the header of your
response accordingly.

While I'm here, though, I'd like to throw in a bit of administrivia.
I will be away from the internet from April 22nd to April 30th.  With
luck you won't notice that I'm gone, but if anything flaky happens I
can't guarantee that anyone here will be able to fix it in my absence.
Please pray to your favorite net.gods that nothing untoward occurs
during that time!

The rest of this message is from Ronald:
-------------

>Adaptations for terrestriality and arboreality are not mutually exclusive.
>The modern felids (from wild cats and ocelats upt to jaguars and leopards)
>work very well both on the ground and up in trees.

I confess that I do not understand the whole arboreal/cursorial
"dilemma".  The modern Cracidae (curassows, guans and chachalacas)
and some other phasianid birds are more or less highly arboreal,
but certainly wouldn't match most people's idea of tree-dwelling
birds.  Why couldn't Archaeopteryx have been something like a
chachalaca, spending time both in trees and on the ground (or in
low scrubby bushes as chachalacas do)?  For that matter are we to
assume that small dromaeosaurids were incapable of pursuing
lizards, etc. up trees or into bushes?  If so, why?  They do't
have to have been canopy specialists to do so.

>This is probably true for Sinornis' lineage.  However, almost all other
>Mesozoic birds (Icthyornis, Hesperornis, Patagopteryx, the
>Enatornithoformes, etc.) are demonstrably nonarboreal.  Thus, Sinornis shows
>that birds were capable of evolving arboreal forms, but is phylogenetically
>distant from the common ancestor of modern perchers/tree dwellers.

The same is true throughout the avian fossil record, because larger
water birds fossilize more frequently than smaller forest birds. 
The Cretaceous record should surprise no one.  I suspect we have
the same bias in pterosaur fossils.  I have no evidence for this
except a gut feeling that Anurognathus couldn't have been the only
small forest dwelling pterosaur when there were so many
specializations among the fish-eaters. 


--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
Home: 1825 Shady Creek Court                  Messages: (416) 368-4661
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