Re: Bird reduce their "heating bills" in cold climates

[Dann Pigdon <dannj@alphalink.com.au>]

On Tue, Jul 6th, 2010 at 1:42 PM, Tim Williams <tijawi@yahoo.com> wrote:

> Jura <pristichampsus@yahoo.com> wrote:
> > Hardly anything about the skeleton of green iguanas,
> > screams arboreal either. 
> 
> This is true.  And, as commonly noted, even goats can climb trees.
> 
> However... if one were to hypothesize that a particular fossil taxon was 
> habitually arboreal,
> then this hypothesis will stand or fall based on its arboreal-related 
> characters.  So far, no
> ornithopod (including _Leallynasaura_ [sic] ) shows any adaptations for 
> climbing or perching.  

Neither do tree kangaroos, arboreal ant-eaters or arboreal foxes. 

The ant-eater's prehensile tail is a bit of a giveaway, but if it were known 
only from fossils then 
chances are the distal caudals would probably be missing in most cases (as they 
are for all 
Leaellynasaura, come to think of it). Plus a prehensile tail doesn't 
necessarily indicate arboreality 
(bettongs, for instance).

Given how well hooved quadrupeds like goats can climb, I'd say that small 
ornithopods could easily 
have had the necessary physical traits for the occasional (or even frequent) 
mad scramble up 
something. I wouldn't expect anything particularly graceful - although lack of 
grace doesn't seem 
to stop tree kangaroos doing their thing.

Generally speaking it's easier to say what *is* arboreal than it is to say what 
*isn't*.

-- 
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Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
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