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Re: Deinonychus claw, er, no, still Catch-22, really...



On 12/15/2011 8:00 PM, Tim Williams wrote:

> The trouble with this hypothesis is that the overall morphology of
> theropods (their bauplan, if you will) was so poorly adapted for
> arboreality.

The trouble w/ *that* hypothesis is that vertical-climbing, refuge, roosting and even perch-hunting are very limited forms of arboreal locomotion, and do *not* require "arboreal adaptations", which occur in animals that *live* in trees.

Some smaller theropods appear to have been physically competent to accomplish such exploits -- making a ground-foraging tree-roosting lifestyle (GFTR) viable.

> Even if (and it is still an*if*) certain characters in
> the hands and feet improved trunk-climbing or branch-holding ability,
> these characters must be set against the rest of the skeleton, which
> remained resolutely terrestrial.

Why? The same can be said of birds.

This is why comparisons between theropods and mammals are so inapt -
including goats.

I would not call pointing out that many surprising "bauplans" occasionally encroach on tree-space "making a comparison".

Even fresh-water turtles sometimes get up into trees a short distance (personal observation).

Theropods lacked the flexible
vertebral columns and range of motion at the joints which, by and
large, are present in mammals.

And theropods need these traits to climb vertically or roost? Why?

> Theropod backbones and joints lack
> even the most basic requirements for arboreality.

No one argues (in this thread) that theropods were arboreal - or if they did, I missed it...