Subject: gaps in the fossil record } the evidence from the fossil record to support evolut

Subject: gaps in the fossil record

} the evidence from the fossil record to support evolution is largely
} missing and that critical gaps indicate a single creation of life
} as it is today.
}The fossil record is incomplete and there are no transitions evident

Such a prediction by creationists is rare.  The implication of this
is that if gaps in the fossil record are ever filled, creationism
is falsified.

Those outside professional paleontology often find it difficult to
access what the fossil record does and does not show.  As someone who
works within the field of human paleontology and human evolution, I
often find it odd when I am told that the number of human fossils is
much too meager to allow the sort of extrapolation claimed by
biologists for human ancestry.   This may have been true 20 years ago,
but it certain is not the case now.

This might lead one to wonder if the fossil record is not also underrated
in the are of other organisms as well.  An article in the book _Science
and Creationism_, edited by Ashley Montague, addresses this point.  The
article is by noted paleontologist  Roger J. Cuffey, one of the witnesses
called to testify in the now famous Arkansas creation science case in
1982.  Allow me to quote form the article, entitled "Paleontological
Evidence and Organic Evolution,":

  "If we read the paleontologic literature (especially if with the
   background of professional paleontologic training and experience)
   we find that the fossil record contains many examples of such
   transitional fossils.  These connect both low-rank taxa (like
   different species) and high-rank taxa (like different classes),
   inspite of the records imperfections and in spite of the
   relatively small number of practicing paleontologists.  Because
   of the critical role which transitional fossils played in
   convincing scientists of the occurrence of organic evolution,
   paleontologists have been appalled that many otherwise well-
   informed persons have repeated the grossly misinformed assertion
   that transitional fossils do not exist."

Cuffey the goes on to list no fewer than 185 references in the paleontologic
literature documenting such transitional forms.  One of my favorites is
the fossil Therapsid, Diarthognathus.  In the fossil record, reptiles are
distinguished from mammals by the number of bones that form the lower jaw.
This is not a trival distinction, since the musculature of the reptilian
jaw is different from that of mammals and would require such a re-design.
Essential, reptiles have a lower jaw made of three bones (dentary, articular
and quadrate) while mammals have only a single bone (the dentary), with the
articular and quadrate relocated to the middle-ear (reptiles have only one
ear ossicle, mammals have three.  The relocation of this bones is observable
embryologically in modern mammals).

Therapsids are "mammal-like reptiles" and have a number of traits that
put them midway between mammals and reptiles.  The skull is larely reptilian
but the dentary is much larger than in modern reptiles and other fossil
reptil groups.  Also, the therapsids have heterdont teeth (different shapes
for different functions as in mammals) and limbs located underneath the body,
rather than out to the side (not as far underneath as in mammals, however).

Diarthrognathus is a therapsid with both a mammalian and reptilian jaw joint.
Both are functional, but the mammal-like joint seems to have been the most
functional.  The quadrate and articular bones are very reduced.  The animal
is literally hafe-way between a mammal and a reptile.

One more thing.  I think it unfair to list Denton with other respected
biologists.  Denton is not a biologists and, while not religious either,
had his own philosophical axe to grind against what he felt are the
dehumanizing implications of evolution.   A recent review of Denton's
book appears in the July-August Issue of the NCSE Reports (published by
the national center for science education ).  The review, by biologists
William M. Thwaites, points out the numerous errors, misintepretations
and misrepresentations in Denton's book.   Denton, as do many religious
creationists, relies on outdated material often quoted out of context,
and does not seem to understand the implications of the examples he
uses, especially those using biochemical evidence.  Thwaite concludes:

   "...Denton's book is just another typical anti-evolution tract.  It
     shows that Dento is motivated, not by a desire to understand the
     workings of nature, but by apparent fear of "agnostic," "materialistic,"
     and "skeptical outlook of the twentieth centure."


}The fossil record is incomplete and there are no transitions evident

The fossil record will never be complete, but it is certainly more complete
than it was in Darwin's day.  Darwin`s prediction that the "holes" would be
filled has come true.  Transitional fossils now exist for all vertebrate
groups.  Transitional forms also exist for most major invertebrate groups
and for most groups of plants.

For those of you without the fortitude to wade through the paleontological
literature, a wonder source of information is an article by Roger J. Cuffey
in the book _Science and Creationism_ (edited by Ashley Montague).  This
book should be fairly easy to obtain.  In the article, entitled "Paleontologic
Evidence and Organic Evolution" Cuffey lists no less than 220 references from
various scientific journals documenting these transitional fossils.  These
transitions include connections between low rank taxa (like species) as well
as high-rank taxa (like classes).

It is interesting that much is made of the "evolution should not be
treated as a fact" when the same people often talk about a lack of
transitional forms between various taxa.  Taxonomic groups are not
facts.  Taxonomy is an order imposed on the living world by scientists
to make the diversity of life easier to deal with.  Nonetheless,
creationists and fellow travellers refer to it like it is written in
in stone.


From stassen@netcom.UUCP (Chris Stassen):
For those interested in evaluating "intermediate forms", I'd recommend
Chris McGowan's _In The Beginning_ (Prometheus).  It's a "good place to
start" for the layman (but by no means sufficient all by itself).  He
devotes two chapters (pp. 110-141) on detailed study of Archaeopteryx
and the Cynodonts, comparing their features to those of the two groups
which they fall between.

While Archaeopteryx appears too late to itself be the transitional form
between reptiles and birds, it does fall between the two categories.  The
Creationists contend that it is a bird - but a detailed study of features
shows that it has less in common with birds (feathers, wishbone) than it
does with Theropod dinosaurs (pubic peduncle, bony tail, no pygostyle, no
bony sternum, three well-developed fingers, three well-developed metacarpal
bones, metacarpal bones unfused, metatarsal bones separate, no hypotarsus,
abdominal ribs).  The first specimen found was accidentally classified as
a reptile because the feather impressions were too faint to discern (until
the fossil was specifically examined for them).

I'll deal with Cynodonts more briefly, but when evaluated in 14 main areas
where reptiles and mammals differ skeletally, they are clearly intermediates.
They share five of the features with reptiles, five with mammals, and are
somewhere in between on the other four.  Since they appear in the fossil
record at the proper time, and are connected by many other "transitional"
fossils in a very detailed sequence, they represent one of the most
well-documented transitional forms.  (It should be no surprise that more
recent transitions are better documented.  More fossils are available,
and more complex creatures probably change more slowly.)