RE: Yet more on pterosaur quad arm posture

[Jason Brougham <jaseb@amnh.org>]

It counts as climbing.

What you probably meant to say is that, though flightless, it has inherited 
features from ancestors, such as the hallux, that allow it to do this.

Again, for perching adaptations to evolve, there was a population of animals 
that went into elevated perches WITHOUT such adaptations, and that provided the 
selection pressure for them to evolve. Were basal paravians all doing that, and 
did it take until, say the Sapeornis node in Avialae for the arboreal 
adaptations to arise?

The only other way it could have happened is if there were exaptations, such as 
gripping feet (Fowler et al. 2011), that allowed elevated perches and were 
later replaced by reversed halluces. This exaptation is reported for 
dromaeosaurs, which are also paravians.

And, when we ask what good the intermediate stages of flapping flight would be, 
a valid answer is "to get 1 meter off the ground into a low roost", because 
living basal birds (tinamous, galliforms, anatids) still share the character of 
roosting this way.


________________________________________
From: owner-DINOSAUR@usc.edu [owner-DINOSAUR@usc.edu] on behalf of David 
Marjanovic [david.marjanovic@gmx.at]
Sent: Friday, July 12, 2013 9:43 AM
To: dinosaur@usc.edu
Subject: RE: Yet more on pterosaur quad arm posture

> OK, my incredule, here is a flightless Weka (Gallirallus australis) in a
shrub:
>
> http://www.flickr.com/photos/trs/3476131920/
>
> And, as I say, chicks and pinioned birds that can't fly do it too.

Let me just quote from what it says under the photo:

"Wekas really aren't meant to be off the ground, and the best part was when 
this particular one kept falling off the branch. I saw this silly bird on Ulva 
Island, a small island in a bay of Stewart Island."

"The tree was more of a large shrub, and it hopped up from branch to branch."

Seriously, this does not count as climbing.

> Of course Strigops does as well, but it is zygodactylous, after all.

It's a parrot. Parrots _are_ good climbers.