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RE: Yet more on pterosaur quad arm posture



I think part of the issue here is mixing terminology from mammology and 
ornithology.

For mammalogists, "arboreal" typically means "animals that feed and live 
primarily in the trees" while "scansorial" means "animals that feed and live 
primarily on the ground, but hide, nap, or roost in trees." Since 
non-chiropteran mammals don't really have the option of flying to get up into 
trees, they have climb in order to get there, and hence "scansorial."

But to ornithologists the focus is on the bird-substrate contact: scansorials 
are explicitly those that use their claws to access the tree environment 
vertically. The distinction here is a locomotory one, not as much an 
autecological one.

Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA

> -----Original Message-----
> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] On Behalf Of 
> David Cerný
> Sent: Thursday, July 11, 2013 3:26 PM
> To: dinosaur@usc.edu
> Subject: Re: Yet more on pterosaur quad arm posture
> 
> David Marjanović <david.marjanovic@gmx.at> wrote:
> 
> >> We agree that animals that are not scansorial do roost in trees.
> >
> > ...if they can fly there. (WAIR probably counts, too.)
> >
> > If they climb there instead -- if they do what practically no bird ever 
> > does today: start on the ground and climb into the crown --,
> they're scansorial: natural selection for climbing ability kicks in, and they 
> evolve adaptations to climbing.
> >
> > Lots of terrestrial or semiaquatic birds roost in trees _because_ they can 
> > do so without climbing.
> 
> I'm sure this _must_ have been mentioned in the discussion about the 
> arboreality of basal maniraptorans at some point (especially
> since that discussion seems to emerge on the list every two months or so), 
> but -- what about seriemas? They are terrestrial, maybe
> even vaguely deinonychosaurian-like (although Farlow et al. 2011 found the 
> comparison largely unsubstantiated), their hallux is
> reduced (like in tinamous), they roost in trees, but they climb up there:
> 
> http://www.oiseaux-birds.com/card-red-legged-seriema.html
> https://plus.google.com/104301904461877588678/posts/MEb3NDJLVTK (with links 
> to photos of seriemas in trees and perched --
> somehow -- on
> branches)
> 
> Perhaps someone can find a better reference; the _Handbook of the Birds of 
> the World_ may be worth checking out.
> 
> 
> *Ref:*
> 
> Fowler DW, Freedman EA, Scannella JB, Kambic RE 2011 The predatory ecology of 
> _Deinonychus_ and the origin of flapping in birds.
> PLoS ONE
> 6(12): e28964
> 
> 
> --
> David Černý