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RE: Thoughts on the new Czerkas book (long)



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Dann Pigdon
>
> I had an interesting thought about "flying" dromaeosaurs recently (yes,
> hold onto your hats - I've been thinking again!)

[discussion of possibility of flying baby, less-flying adult dromaeosaurs]

Actually, you are not far off of my own (and others) favored scenario, with
a slight modification.  That modification came at last year's SVP meeting,
and Ken Dial's mind-altering presentation!!  I hope Dial gets that published
soon, as his study basically overwrites nearly every aspect of the debates
of flight origin, and does so by documenting real behaviors and invokes no
unusual ecological circumstances (see
http://www.cmnh.org/dinoarch/2001Oct/msg00197.html, and other posts from
last October).

That is, I would say the evidence is most consistent with a standard model
of phylogeny (mine, Sereno's, the AMNH, Rauhut's: sure, we have our
differences, but the basic framework is the same), the evolution of long
arms, more laterally oriented glenoids, and elongation of arm plumage to
produce broad feathers in the basal maniraptorans.  These forms *while
small* used these as wings, in so far as they used them in wing assisted
incline running, as do basal birds today (that is, many basal birds are not
long-distance fliers).  From this ancestral condition several different
possiblities could (and seemed to have) evolved:
        * Forms which became larger as adults, and subsequently had a more
terrestrial lifestyle (therizinosauroids, big deinonychosaurs, etc.)
        * Forms which remained small, but never seemed to have evolved
specializations associated with tree-to-tree flight (maybe critters like
Microraptor, for example)
        * Forms which developed enhancements for tree-to-tree flight, including 
the
ancestors of modern birds
        * Forms that may have had other locomotory behaviors which haven't been
explored scientifically yet (four "winged" Cryptovolans, for instance)

Food for thought...

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796