An end to miracles (was Re: New alvarezsaurid)

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 02:23 PM 3/30/98 EST, Dinogeorge wrote:
>In a message dated 98-03-30 13:19:37 EST, znc14@TTACS.TTU.EDU writes:
>
><< Of course, an intuitively pleasing adaptive story cannot supplant a
> reproducable phylogenetic analysis. >>
>
>I wouldn't mind an intuitively pleasing adaptive story-->any< adaptive
>story--that didn't include miracles, unlike the stories currently in vogue,
>some of which are supposedly supported by phylogenetic analysis.

Okay, George, we've let you go on and on and on about this. You've had your say.

Now, time for you to clarify:

What is so miraculous about evolution?  Evolution BY NECESSITY can only
operate from previously existing structures.

Take insect flight:  Either modified gills or modified body lobes are
present for some other reason, but are selected for so that (in one lineage)
they become used for flight.  No "miracles" required.  A posteriori it might
look "unlikely", but the same can be said of almost any complex structure.

Take bones: originally vertebrates had cartilage skeletons and bony
integument.  One lineage developed a bony axial skeleton and reduced the
ossified exterior.  This was selected wholly within the context of the
aquatic environment.  One branch of bony fish also developed lobed-fins,
again in the context of a subaqueous environment.

And yet, if these adaptations had not arisen for entirely different
purposes, sarcopterygians would not have had the particular suite of
structures that allowed them to give rise to Tetrapoda.  And even if a
primarily cartiligenous group of pseudo-tetrapods had evolved, without
ossified bone (evolved for entirely different reasons) they would not have
been capable of assuming an upright stance, or reaching large size.

Take milk: slime glands evolved in an aquatic context are modified into
protective mucous glands in a terrestrial context are modified into seat
glands are modfied into milk glands.  A "miracle"?

Your argument is precisely the argument used by creationists.

So, now the test of science: would you change your position on the origin of
avian flight if presented with evidence which contradicted your model? (I'm
not saying that that evidence exists; I am only setting up a hypothetical case).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661