RE: Do we have dromaeosaurid evolution backward?

["Thomas R. Holtz, Jr." <tholtz@umd.edu>]

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu] 
> On Behalf Of Matthew Martyniuk
> Sent: Thursday, August 25, 2011 8:41 AM
> To: DML
> Subject: Re: Do we have dromaeosaurid evolution backward?
> 
> I may misunderstand the principles behind WAIR, but a lot of 
> arguments I've read here and elsewhere in support of it as a 
> precursor to flight strike me as circular. In all the 
> literature and videos I've seen concerning how WAIR works, a 
> complete upstroke appears to be necessary. 

Right here is the misunderstanding.

WAIR is possible with anteroposterior flapping (modern birds do this, and 
kinematically possible by non-ornithothoracine
maniraptorans), whereas flapping flight requires dorsoventral flapping. Thus, 
you can do WAIR without a full "above the shoulder"
excursion of the humerus.

(You--well, birds--can *also* WAIR using the full dorsoventral flap.)

Also, WAIR has the advantage as a selective regime for the origin of flight 
because it can work incremental: it isn't all "all or
nothing" situation, but rather any slight change in feather size, power to the 
forelimbs, etc. directly benefits to the angle of
ascent possible. That is to say, a non-ornithothoracine need not be as good at 
WAIR as any living bird but still get a selective
advantage in its use. AND that advantage literally puts it in a situation were 
selective pressures for other uses of pennate
feathers and aerial locomotion are possible.

A good review of WAIR studies can be found in 
http://dbs.umt.edu/flightlab/documents/BioScienceDialetal06_002.pdf

And don't forget to check out the literature on Controlled Flapping Descent 
(CFD), the oft-neglected downward "trees down"
counterpart to WAIR 
(http://dbs.umt.edu/flightlab/documents/JacksonSegreDial2009_Proceedings.pdf).

http://dbs.umt.edu/flightlab/ is your one-stop non-shopping (i.e., free) site 
for all your WAIR-related publications and videos...

(No, I'm not getting kick backs from Ken Dial to post this...)


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