From: folta@cs.umd.edu (Wayne Folta)
Newsgroups: talk.origins
Subject: Re: Creation Evidences
Date: 17 Dec 92 04:12:00 GMT
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742

>How about stuff like meteoric dust, the decay of the earth's magnetic
>field, Archaeopteryx is classed as bird, the recession of the moon, 
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>and other classic young-earth creationist drivel.

I have been reading Evolution: A Theory In Crisis, by Michael Denton. In my
reading, I cannot tell what he believes as an alternative to Evolution, and
he is certainly not a Young Earther, as he accepts the standard eras and times
at face value. But he does take exception to the Archaeopteryx proof text:

   Evolution: A Theory In Crisis, pp 176-178

   Despite the generally discontinuous character of the fossil record there
   are some exceptional cases where a species does appear to be intermediate
   with respect to other groups. The classic case of this is, of course,
   Aechaeopteryx, a picture of which is shown in Figure 8.2. This primitive
   bird does indeed possess certain skeletal reptilian features -- teeth, a
   long tail, claws on its wings. However, in one respect, flight, the most
   characteristic of birds, Archaeopteryx was already a true bird. On its wings
   there were flight feathers as fully developed as any modern bird, and
   recent [the book is copyright 1986] research reported in 1979 (55) suggests
   that it was as capable of powered flight as a modern bird.

   Commenting on the structure of the wing of Archaeopteryx, Savile
   remarks (57):

      The eight primaries are graduated proximally and distally to form a
      nearly elliptical wing tip of surprisingly modern appearance.... The
      wings were not preserved in fully extended position, but they seem to
      have been nearly eliptical in outline, and, except for the lack of an
      alula or emarginated primaries, are not unlike those of many passerines
      in general appearance.
   
   No doubt it can be argued that Archaeopteryx hints of a reptilian
   ancestry but surely hints do not provide a sufficient basis upon which
   to secure the concept of the continuity of nature. Moreover, there is no
   question that this archaic bird is not led up to by a series of transitional
   forms from an ordinary terrestrial reptile through a number of gliding
   types with increasingly developed feathers until the avian condition is
   reached.

   ...

   To demonstrate that the great divisions of nature [he has been making the
   case for non-continuity and this excerpt assumes this] were really
   bridged by transitional forms in the past, it is not sufficient to find in
   the fossil record one or two types of organisms of doubtful affinity
   which might be placed on skelatal groundsin a relatively intermediate
   position between two other groups. The systematic status and biological
   affinity of a fossil organism is far more difficult to establish than in
   the case of a living form, and can never be established with any degree
   of certainty. To begin with, nonety-nine per cent of the biology of any
   organism resides in its soft anatomy, which is inaccessbile in a fossil.
   [Actually, this is not 100% the case, I believe.] Supposing, for example,
   that all marsupials were extinct and the whole group was known only bt
   skeletal remains -- would anyone guess that their reproductive biology
   was so utterly different from that of placental mammals and in some ways
   even more complex?

   Modern birds differ greatly from reptiles in many physiological
   and anatomical characteristics, particularly, for example, in their central
   nervous, cardiovascular and respiratory systems (the respiratory system of
   birds is discussed in detail in the next chapter) but, because information
   about the soft biology of a fossil is difficult to obtain from its
   skeletal remains, to what extent Archaeopteryx was avian in its major
   organ systems will always be largely a matter of conjecture.

I am tired of typing (I am not a touch typist), but I'll summarize the
rest. Basically he says that the brain cavity exhibits typically avian
hemispheres and cerebelum. And since it had totally avian wings, feathers,
and brain, and if it could fly, it is likely that it had avian lungs, heart,
and circulatory system.

In the next chapter, he describes in great detail the avian lungs, which are
unlike any other lungs: flowthrough. This creates enormous difficulties for
a step-by-step evolution from a reptile's lungs. Even how the lungs form
during development are very much different from other lungs. And the fact that
there is essentially no variation in avian lungs increases the suspicion
that no fundamental variation of the avian lung is compatible with it working.

He then mentions other differences: heart, cardiovascular system, gastro-
intestinal system, syrinx, etc. which add up to an enormous conceptual
difficulty imagining gradual evolution.

His references are:

(55) Olson, LS and Feduccia, A (1979) "Flight and the Pectoral Girdle of
     Archaeopteryx", Nature, 278:247-48.
   
(57) Savile, DBO (1957) "Adaptive Evolution in the Avian Wing", Evolution,
     11:212-24, see p 222.

In Darwin On Trial, the reasoning is different:

   Archaeopteryx ("old wing"), a fossil bird which appears in rocks estimated
   to be 145 million years old, was discovered soon after the publication of
   The Origin of Species, and it thus helped enormously to establish the
   credibility of Darwinism and to discredit skeptics like Agassiz.
   Archaeopteryx has a number of skeletal features which suggest a close
   kinship to a small dinosaur caled Compsognathus. It is on the whole
   bird-like, with wings, feathers, and a wishbone, but it hsa claws on its
   wings and teeth in its mouth. No modern bird has teeth, although some
   ancient ones did, and there is a modern bird, the hoatzin, which has claws.

   Archaeopteryx is an impressive mosaic. The question is whether it is proof
   of a reptile (dinosaur) to bird transition, or whether it is just one of
   those odd variants, like the contemporary duck-billed platypus, that have
   features resembling those of another class but are not transitional
   intermediates in the Darwinian sense. ...

   ...

   ... According to a 1990 review article by Peter Wellnhofer, a recognized
   authority, it is impossible to determine whether Archaeopteryx actually
   was the ancestor of modern birds. Wellnhofer concludes that "this
   correlation is not of major importance," because the Archaeopteryx specimens
   "provide clues as to how birds evolved," and because "They are powerful
   documents without which the idea of evolution would not be powerful."

   ...

   Archaeopteryx is on the whole a point for the Darwinists, but how important
   is it? Persons who come to the fossil evidence as convinced Darwinists
   will see a stunning confirmation, but skeptics will see only a lonely
   exception to a consistent pattern of fossil disconfirmation. If we are
   testing Darwinism rather than merely looking for a confirming example or
   two, then a single good candidate for ancestor status is not enough to save
   a theory that posits a worldwide history of continual evolutionary
   transformation.

So is disagreement on Archaeopteryx "drivel" or is it not as clear as the
previous poster made it out to be?
-- 


Wayne Folta          (folta@cs.umd.edu  128.8.128.8)