Re: Thou Shalt Not Climb!

[mariusromanus@aol.com]

Well, what I'm saying is a bit different though... I'm thinking that 
some of the pre-perching aspects of these basal birds and related 
theropods were selected for climbing before flight took off in 
theropods, and before perching took place in birds... (greater range of 
motion on the front limb, large digits, bigger pectoral region, 
possible use for the "killing toe" was dual, or even "scansorial" 
before it was predacious etc....)


Kris
Saurierlagen@gmail.com


-----Original Message-----
From: T. Michael Keesey <keesey@gmail.com>
To: Dinosaur Mailing List <dinosaur@usc.edu>
Sent: Fri, 29 Jun 2007 4:06 pm
Subject: Re: Thou Shalt Not Climb!


On 6/29/07, mariusromanus@aol.com <mariusromanus@aol.com> wrote:Â
> Â
> Were basal birds up in the trees before they had the modern traits weÂ
> now use to define a bird as arboreal??? If yes, what were the traitsÂ
> that allowed them to be there? If not, then why did selection favorÂ
> characteristics for an arboreal lifestyle?Â
Â
Aren't most terrestrial vertebrates (below a certain size) capable ofÂ
getting into trees? There's even at least one non-tetrapod capable ofÂ
it: mudskippers.Â
Â
I would imagine that archosaurs (and amniotes and crown-tetrapods)Â
have "ability to get into a tree" as the ancestral condition, onlyÂ
absent in some lineages due to derived conditions (large size,Â
fossorial or aquatic adaptations, armor, etc.).Â
Â
Seeing as few pan-avian subclades have derived conditions like theseÂ
(except for "large size"), and seeing as they all began life at aÂ
relatively small size, I would think most were capable of getting intoÂ
trees. The preconditions for arboreality are pretty old, I think.Â
-- Mike KeeseyÂ


________________________________________________________________________
AOL now offers free email to everyone.  Find out more about what's free 
from AOL at AOL.com.
=0