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RE: Peering at review




-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
Jaime A. Headden
Sent: Monday, October 21, 2002 9:49 PM
To: dinosaur@usc.edu
Cc: Dinogeorge@aol.com
Subject: Re: Peering at review

George Olshevsky (Dinogeorge@aol.com) wrote:
<I say that, as with birds today, once you have a finch, you soon have
fifty species of finches; once you have an eagle, you soon have dozens of
species of eagles. And once you have archaeopterygid, you soon have dozens
of species of  archaeopterygids, all over the world. And hundreds or
thousands more dino-bird species less closely related to archaeopterygids.
They were there all right, and maybe given time we'll be lucky enough to
find some.

The existence of one species of finch is evidence for the existence of
dozens  of kinds of finches. Likewise, the existence of Archaeopteryx is
evidence for  the existence of dozens of species of archaeopterygids.>

  Show us the evidence. The essential flaw I see in this reasoning is
thus: You presume present diversity of some groups of birds means that any
fossil of one must mean dozens of species of that fossil-type.<<

Lets put it this way, go outside and see how many birds are flying around.
Take your time. How many will those fossilize? How many animals will
fossilize in a tropical forest? How many animals are living there? When a
fossil tropical forest is found in the geological record and little or no
fossils, are we then to ASSUME that there were no or little animals living
there because none or few were found? Liaoning and the Solnhofen are great
for finding fossil animals but we we'll NEVER know the true diversity of the
area because not every animal/type/group will be fossilized. Thus are we to
assume they weren't there?

The geological record is bias and the lack of fossil evidence is no reason
to ASSUME they weren't there. Negative evidence (as pointed out before)
works both ways.

>> No. There
are not dozens of species of hoatzin, for example, and finding a fossil
*Opisthocomus* would mean you found a fossil of _an_ *Opisthocomus;* it is
illogical to presume a greater positive value of forms on such data.<<

So, different animals, different diversities, different living habitats.
It's like apples and oranges.

>> We
have a set of seven skeletal fossils of archaeopterygid, perhaps two
species, perhaps _five_, but these are based on criteria of morphological
variation. In a sense, a neontologist would scoff at the absence of
genetic or biogeographic data when formulating a species; they would argue
for the variety of form and condition of features in living animals, such
as populations or sexes of *Geospiza* finches or the I'iwi. Conversely,
they would argue that most species of barbet and finch vary not at all
morphologically but are defined by size, coloring, location, geography,
which may all influence each other and result in what I know as
neontological "splitting."<<

But there's lots of them right?

>>  Present data argues that a fossil form does not mean hundreds of members
are "waiting to be found, thus supporting this contention" but that there
is a fossil with a specific morphology. I doubt all the specimens of the
Santana compsognath will have such variable opening of the various
obturator fenestrae, and this is likely to influence ideas, as in most
allosauroids/carnosaurs the relation of obturator aperture size and extent
of the defining bony rim, and how this means anything to phylogeny.<<

Hasn't there been a study somewhere where they predicted the about of
fossils found to the amount of animals living at the time? The fossil record
is not a true gauge of the diversity of life, though too many people do. The
diversity and the population of animals IS (and I can not stress this
enough) much larger than the fossil record will EVER show and it cannot be
taken as a true gauge of fossil diversity.


  Cheers,

=====
Jaime A. Headden

Tracy L. Ford
P. O. Box 1171
Poway Ca  92074