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Giant flightless birds (was CNN: how birds first flew)



(Oops,...forgot to "reply to ALL". but that`s ok, cause Dr. Tom seems to
take the weekends off anyway....GOOD FOR HIM! 8^)



----- Original Message -----
From: Thomas R. Holtz, Jr. <th81@umail.umd.edu>
To: Larry Febo <larryf@capital.net>
Cc: <dinosaur@usc.edu>
Sent: Friday, May 07, 1999 5:55 PM
Subject: Re: CNN: how first birds flew

>
> But can you provide evidence why that model should be favored over any
other
> model, without resorting to "I like this model better" or "I can't imagine
a
> better way it could have happened"?  If so, you can suggest ways to test
> between two (or among more) models.

Well, I don`t know if it offers any kind of "test", but the original reasons
behind my thinking that theropods are all secondarily flightless is the fact
that the condition of secondary flightlessness has happened so many times in
nature, (witness all those Phorusrachids), as well as present day
Ostritches, Emus etc. It seems to be a natural pattern that such flightless
forms become larger, (in many cases much larger). Probably has something to
do with the freedom from genetic restraint to remain small for flight
purposes.
Years before Ostrum showed how closely birds are related to dinosaurs
through comparisons of Archaeopteryx and Dromaeosaurs, I took one good look
at the legs of T_Rex and said to myself "Bird,...that`s definitely some kind
of giant flightless bird!" So, the head and claws didn`t look particularly
"birdlike", but then again, neither do those of Archaeopteryx!
I still think if there were lots of birds around with claws and teeth today,
there would also be cursorial forms that would look more like Mesozoic
theropods. It`s the evolution of the basic stock of birds toward more
specialized wings without claws, and beaks without teeth, as well as more
ridgid structure of their frames that has ruled out production of such forms
in modern times.