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Re: Feduccia (was: polarity of bipedality in dinosaurs)



I'm sorry if it seems like I'm beating this thing to death.  Personally,
I've been waiting a long time (George is a bit busy to always answer direct
e-mail challenges) to have this one out.  If people no longer think it is
useful to the list, I'd consent to unilateral disarmament.  :)

At 02:46 PM 9/26/96 -0500, Dinogeorge wrote:

>How flying birds might have evolved from terrestrial, cursorial
>forms is nearly impossible to determine, but it must have happened,
>to account for all those synapomorphies.

        No, actually, plenty of theories as to how have been proposed.
Perhaps you are confusing lively scientific debate with an inability to
determine the *truth*.  Seems to me that, with all your lecturing on how
science works, you of all people should realize that it's perfectly ok for
science to not have all the answers.  Sometimes professionals are befuddled,
not because of some flaw in their paradigm, but simply because the best
solution hasn't presented itself.
        
>Paleornithology says this: Birds can't possibly be dinosaur descendants
>because no known dinosaurs were properly placed in time

        Irrelevant.  See below...

> or had the kinds of arboreal or acronomic lifestyles that gave rise to birds.

        Not provable.

>the BADD cladistic studies have found must be due to convergence, 

        As Ron Orenstein has pointed out, what could possibly be the
convergent pressures that would make an arboreal, flying, possibly
insectiverous animal and a cursorial hyperpredator that kills with a
retractable toe claw come out looking nearly identical?

>and true avian ancestors remain unknown.

        Important point, they are obsessed with finding an _ANCESTOR_.  The
search for missing links was given up by the rest of science years ago.
Maybe it's time they stopped...

>BCF reconciles these viewpoints:

        Actually the two don't need to be reconciled, as I point out above,
one of them is faulty.

>descent of dinosaurs from small, arboreal archosaurs in the process of
>evolving into true (avialan) birds, just the way paleornithologists say they
>did.

        And, incidentally, the way some more mainstream paleontologists have
suggested (Greg Paul).

        Also, I don't believe that BCF explains how these little
"lizardlike" arboreal animals began incorporating more vertebrae into their
sacra and fusing them together.  The animals George describes would not need
this kind of extra support until they returned to a terrestrial, cursorial
niche.  Yet, all birds show these adaptations...  Maybe the BCF birds are
secondarily flighted?

        Wagner
+-------------******ONCE AGAIN, NOTE NEW E-MAIL ADRESS******---------------+
| Jonathan R. Wagner                    "You can clade if you want to,     |
| Department of Geosciences              You can leave your friends behind |
| Texas Tech University                  Because your friends don't clade  |
| Lubbock, TX 79409                               and if they don't clade, |
|       *** wagner@ttu.edu ***           Then they're no friends of mine." |
|           Web Page:  http://faraday.clas.virginia.edu/~jrw6f             |
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