ORG:ARCHAEOPTERYX (the hope of every evolutionist)

   Are the features of the archaeopteryx so overwhelmingly and/or
convincingly reptilian as to lead necessarily to the conclusion it is a
transition between the bird and the reptile? And if the bone structure
was very similar would the natural conclusion still be that the
archaeopteryx is a transition?

   "The Neck of the Giraffe: Where Darwin Went Wrong" Francis Hitching
1982 pp34-36

   Fortuitously for Darwin and his theory, it seemed, Archaeopteryx was
discovered in limestone rocks in Bavaria in 1860 less than two years
after The Origin of Species was published. First, the outline of a
feather was seen, giving rise to its name, which means simply 'ancient
bird'. A year later, in a nearby quarry, an almost complete skeleton
was found, its wings outstretched, with a clear imprint of feathers on
them.

   Its importance, then and now, was that Archaeopteryx appeared in the
same strata as dinosaur fossils, and appeared at first sight almost as
much a reptile as a bird-'a providentially timed confirmation of
Darwin's proposition that one group of animals developed into another
by way of intermediate forms', it was recently suggested. Biologists as
a whole regard it as authoritative evidence of Darwinian evolution at
work. 'It proved beyond any argument' that there existed an animal with
both reptilian and bird features, according to one account 'even today,
there is no more convincing example' of a transitionary link, says
another.

   But is the case for Archaeopteryx quite so unambiguous as these
claims make out? Apparently not. Everyone of its supposed reptilian
features can be found in various species of undoubted birds.

   1. "It had a long bony tail, like a reptile's on which feathers
grew." While it is generally true that reptiles have tails, and birds
appear not to, the detailed position is more complex. In embryo, some
living birds have more tail vertebrae than Archaeopteryx does, which
later fuse to become an upstanding pygostyle. The bone and feather
arrangement on a present day swan shows striking similarities to
Archaeopteryx. According to one authority, there is no difference in
principle between the ancient and modern forms: 'the difference lies
only in the fact that the caudal vertebrae are greatly prolonged. But
this does not make a reptile.'

   2. "It had claws on its feet and on its feathered forelimbs." But so
do some modern birds, such as the hoatzin in South America and the
touraco in Africa. The ostrich of today, which also has three claws on
its wings, has been suggested by some experts to have more reptilian
features than the Archaeopteryx- but nobody, of course, considers the
ostrich to be a transitional form.

   3. "It had bony jaws lined with teeth." Modern birds do not have
teeth. But many ancient birds did, particularly those in the Mesozoic,
and there is no suggestion that these are intermediates. It is just as
convincing to argue that archaeopteryx was an early bird with teeth.

   4. "It had a shallow breastbone that would have given it a feeble
wing beat and poor flight." Modern woodcreepers such as the hoatzin
have similarly shallow breastbones, and this does not disqualify them
from being classified as birds. And there are, of course, many species
of bird, now and in the past, which are incapable of flight.

   In any case, recent examination of archaeopteryx's feathers at the
Smithsonian Institution has shown that they are the same as those
belonging to many modern accomplished fliers. 'This implies at the very
least that the beast could glide at some speed and lays to rest the
notion that the feathers evolved as either heat insulation or as an aid
to trapping insects.'

   5. "Its bones were solid, not thin or hollow, like a birds." Another
idea that has been drastically revised. The long bones of archaeopteryx
(wings, legs) are known now to have been both thin AND hollow.[We both
agree here- G.F.] It is still debated whether they were 'pneumatized'
like a bird's, i.e. containing an air sac.

   6. "It predates the general arrival of birds by sixty million years"
Until 1977, archaeopteryx was uniquely early in the fossil record. But
in that year, archaeologists from Brigham Young University discovered,
in western Colorado, a fossil of an unequivocal bird, in rocks of the
same period as archaeopteryx. Professor John Ostrom of Yale University,
who positively identified the specimen, commented: "It is obvious we
must now look for the ancestors of flying birds in a period of time
much earlier than that in which archaeopteryx lived.'

   This discovery much weakens the case for archaeopteryx as an
intermediate, and makes it that much more likely that the creature was
just one of a number of strange birds living at that time. Professor
Heribert-Nilsson commented forcefully that 'they are no more reptiles
than the present day penguins with their wing- fins are transitional
forms to fish'.

   The further point might be made that even if archaeopteryx is in
fact a half-way form from reptiles to birds, it is still not very
enlightening about the process of evolution, nor in any way evidence of
Darwin's hoped for gradual transitions. For that, we would have to see
in the fossil record the slow development of feathers (perhaps from
scales, perhaps from some other origin) and the hierarchical change of
amphibian dinosaurs into delicate, light- boned creatures that could
soar above the Earth. And here, characteristically, the rocks are mute.

   "Evolution: The Challenge of the Fossil Record" by Dr. Duane Gish
copyright 1985 page 110

   In Dr. Gish's book he has put together an excellent analysis of the
Archaeopteryx:

   In reference to Archaeopteryx, Ichthyornis, and Hesperornis, Beddard
stated: "So emphatically were all these creatures birds that the actual
origin of Aves is barely hinted at in the structure of these remarkable
remains." During the eightyfive years since the publication of
Beddard's book, no better candidate as as intermediate between the
reptiles and birds than the Archaeopteryx has appeared. Not a single
intermediate with part-way wings or partway feathers has been
discovered. Perhaps this is why, with the passage of time,
Archaeopteryx, some evolutionists today not only assert that the bird
is undoubtedly linked to reptiles but that if clear impressions of
feathers had not been found, Archaeopteryx, would have been classified
as a reptile. This is a gross overstatement, to say the least.

   "Evolution: A Theory in Crisis" by Dr. Micahel Denton.

   Page 176: 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 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.

   "Adam and Evolution" By Professor Michael Pitman copyright 1984

   pg 221 Although no fossils lead up to or away from it, Archaeopteryx
is often paraded as THE link fossil. there are five specimens of this
bird from Solnhofen limestone in Germany. Usually shown in textbooks is
the Berlin specimen. It has birdlike features in the form of wings,
beak, sclerotic eye-rings, fusion of the upper footbone into an extra
section of the limb, an opposable hind claw and, of course, feathers.
reptilian features include teeth in the bill, claws on the wings and a
long bony feathered tail.

   Are these features so reptilian? Just as the pteranadon is seen as a
distinct, extinct type of reptile, so the creationist regards the
Archaeopteryx as a distinct type of bird. He argues that the 'reptilian
features' fall within the sphere of variability of a bird. We ourselves
have arm-bones similar to those of a bird, a whale and a bat, but are
distinct from these types...

   ...In the earliest known fossils of pterodactyls, bats and winged
insects, the instrument of flight is fully developed. Just so, the
wings and feathers of Archaeopteryx are as perfect as in modern birds.
Assymetric flight feathers resemble those of strong fliers; tailfeather
arrangement parallels that found in modern swans and hens. It is a moot
point just how good or bad at flying the Archaeopteryx was. There are
living flightless birds, such as the kiwi, with very small breastbones,
and not much keel (on to which the flight muscles are attached).
Indeed, many birds 'have wings, won't fly'; these include emus,
cassowaries, rheas, swimming birds (penguins), ostriches, extinct
dodos, and moas.

   ...You can see why it is argued that the Archaeopteryx falls within
the sphere of a variation of a bird. The bony tail? this is a
distinctive feature and the Archaeopteryx is , in fact, classified in a
sub-class all its own. In the embryo some living birds have more tail
vertebrae that 'archy', which later fuse to become an upstanding
pygostyle. It is certainly a permutation on the usual tail-end
subroutine for birds, but so are its vertebrae, which have no saddle-
shaped articulations. This 'reptilian' feature is also found in
cormorants, darters, gulls and certain parrots.

   The free (unfused) foot-bones and wrist bones, found in
archaeopteryx, are also found outside of reptiles- in penguins. Indeed,
archaeopteryx had perching feet...

   What about the teeth? No living birds have socked teeth but some
fossil ones did. Some reptiles have teeth, some have not. The same
applies to fishes, amphibia and mammals...

   In most modern birds, but not archaeopteryx, the plan for the fibula
and tibia legbones is modified, developmentally, so that the fibula is
much reduced and the result is a single structure- the tibia with ankle
bones fused to it and the 'vestigial' fibula along side it- which
articulates the footbones. Developmental manipulation of chick embryos
by Frenchman Armand Hampe' 'allowed' the fibula to attain the same
length as the tibia- as it normally does in vertebrates; articulation
with the ankle bones changed accordingly. Where the evolutionist sees
Hempe's results as an expression of ancestral relationship in
leg-bones, the creationist sees it as a modification, suitable for most
birds, in the vertebrate program.

   A similar interpretation applies to wing claws. In most modern birds
they are suppressed but the young ostrich, rhea and the touraco of
Africa have them. So do young South American Hoatzin, a bird which
shares a number of features with the Archaeopteryx. It leaps, flaps and
dives about wood rivers and swamps of the Amazon valley today.

   Archaeopteryx could represent a group of distinct organisms that
showed the characteristics of bird and reptile. No other fossils lead
either to or from it.... Links are not links if they are mosaics of
complete functional traits from other groups. whales and seals have a
mixture of fish and mammal traits, penguins have fin-shaped wings and
bats are a mixture of bird and mammal but no one calls them
intermediate. No doubt Archaeopteryx is an odd mixture of subroutines
but so are many other creatures.

   Because bird types are found from the early Cenozoic, it seems only
a matter of time before they are found in the Cretaceous or Jurassic
beds. Already Cretaceous Icthyornis shows signs of having been a tern:
and in 1977 'Dinosaur Jim' Jensen found an avian femur and two
connected shoulder bones in Jurrassic rocks, where he had previously
excavated his dinosaurs in Western Colorado. The splendid isolation of
the Archaeopteryx was relieved by a bird which predated it.

   Let's say we decide that the bone structure of the Archaeopteryx is
definitely reptilian, from which line of reptiles is it related?
Surely, there would be traces of one or the other.

   Martin, Stewart, and Whetstone, "The Auk" (Ornithological Journal)
January 1980 page 86 "The Origin of Birds: Structure of the Tarsus and
Teeth"

   "...virtually every major group of reptiles has been purported to be
closely related, if not ancestral to birds."

   In the report they briefly mention two hypotheses concerning
Archaeopteryx and proceed to push their own- crocodile ancestry based
on teeth. The hypotheses are:

   1)A theory of their ancestry from Triassic pseudosuchian archosaurs.

   2) A theory of direct derivation of birds from theropod dinosaurs.

   3) A close relationship between birds and crocodilians.

   It should be noted that in their report that altho' they
concentrated on the Archaeopteryx, the authors clearly related the
teeth of this bird to the teeth of later Mesozoic birds and spoke of
them as one in the same. They were mainly dealing with the origin of
teeth in all teeth-bearing birds.

   In another report that I mentioned a while back in "Nature" Sept 8
1983 pp99-100 entitled "No consensus on Archaeopteryx" The author Dr.
Michael Benton (not to be confused with Dr. Michael Denton) concerning
the different theories:

   " The relationships of Archaeopteryx and the origin of the birds are
controversial. In a recent review, Thulborn and Hamley identified seven
hypothses concerning the affinities of Archaeopteryx, three of which
appear to have supporters at present."

   Just prior to this, Dr. Benton discusses the results of
Archaeopteryx cranial studies:

   "In the new work that has been done on the braincase of
Archaeopteryx by Whetstone, the cranium of the 'London' specimen has
been removed from its limestone slab and painstakingly prepared by
mechanical means. This has shown that the skull is much broader and
more bird-like than had been thought. Details of the braincase and
associated bones at the back of the skull seem to suggest that
Archaeopteryx is not the ancestral bird, but an off-shoot from the
early avian stem." He goes on for the rest of the paragraph discussing
very briefly how it is primitive in some respects and advanced in
others. But basically the Archaeopteryx has been, according to him,
relagated from the lofty position of being the transition between
reptile and modern bird to that of just another "side branch" of
evolution.

   So you see, the reptilian features of the Archaeopteryx are so
obscure and ambiguous that trying to pin down its ancestral
relationship is just about impossible. Forcing the Archaeopteryx into
the role of transition has proved to be nothing but a fruitless
exercise.

   But let's say for the sake of arguement that the Archaeopteryx's
bony structure can be related to reptiles as well as birds. Does this
still necessarily force us to conclude that it is transitional?

   "Evolution: Nature and Scripture in Conflict?" by Dr. P.T. Pun
copyright 1982

   Archaeopteryx has been cited frequently as the transitional type
between reptiles and birds. It has a birdlike skull and wings with
feathers. The reptile features are presented by clawlike appendages,
the possession of teeth, and the long vertebral column that extends to
the tail. The flying power of this organism was presumably slight, for
the wingspread is much less than that of the poor flyers among modern
birds.

   Since most skeletal features of birds can be matched by some
archosaurian reptiles, feathers have been considered the only
distinctive feature of birds. Feathers are essential to birds for
insulation against loss of body heat, and this contrasts greatly with
reptiles since they are cold-blooded. Therefore, Archaeopteryx was
definitely bird. However the presumed small sternum, the primitive
reptilian structure of wing bones, and especially the long tail set
Archaeopteryx apart from most modern birds, requiring a separate
subclass to represent it. However, some reptilian structures of this
fossil are shared by some modern-day birds. For example, the juvenile
stages of Opisthocomus hoatzin of South America and Touraco cory thaix
of Africa possess claws, and both are flyers...

   ...More specifically, L. de Nouy, an evolutionist, commenting on the
status of Archaeopteryx has made a very succinct statement concerning
the establishment of "true links" between major groups. While
recognizing the morphological similarities of Archaeopteryx to reptiles
and birds, he nevertheless concluded:

   "By link, we mean a necessary stage of transition between classes
such as Reptiles and Birds, or between smaller groups. An animal
displaying characters belonging to two different groups can not be
treated as a true link as long as the intermediary stages have not been
found, and as long as the mechanism of transition remains unknown."

   Other quotes from people concerning the Archaeotperyx:

   "Evolution and Christian Faith" by Dr. Bolton Davidheiser Ph.D.
Zoology Johns Hopkins Univeristy. (Altho this book has an original
copyright of 1969 it is presently in its eleventh printing and is
copyrighted 1986).

   The derivation of birds from reptiles seems to be one of the most
thoroughly accepted sequences in evolution. Thomas Henry Huxley called
birds glorified reptiles, and this witicism is still frequently
encountered when the evolution of birds is discussed. It is commonly
stated that if the remains of Archaeopteryx ,"the earliest known bird",
had been found without feathers, it would have been reconstructed as a
bipedal reptile...

   ...Among living creatures birds, and only birds, have feathers. Thus
a feather defines a bird. This definition is extrapolated backward into
the past, and Archaeopteryx is called a bird. Altho' a great many othe
anatomical characteristics, including such things as eyes, hooves, and
excretory tubes, are believed to evolve separately in different
evolutionary lines, it seems that very few evolutionists have even
considered the possibility of feathers having evolved more than once.
The possibility of feathers having been created is not considered at
all, and they are usually said to have evolved from the scales of
reptiles.

   Archaeopteryx had fully developed wings. Nothing has ever been found
evolving from a reptile with partially developed wings. Since the
Archaeopteryx has some reptilian characteristics and some avian
characteristics it is considered to be a link between the reptiles and
birds. But this does not necessarily mean that it does connect the
reptiles with the birds. As previously mentioned, a fossil named
Seymouria has some amphibian-like and some reptile-like
characteristics. It seems to make a good connection between the
amphibians and reptiles, but G.F. Kerkut points out that it cannot be a
connecting link because it lived at the wrong time. If a "suitable"
fossil cannot be a connecting link because it lived at the wrong time,
it is obvious that a "suitable" fossil is not necessarily a connecting
link if it happens to live at the "right" time...

   ...Except for the frequently repeated statement that birds evolved
from reptiles, the evolution of birds is by no means clear in the minds
of evolutionists. J. Arthur Thomson of the University of Aberdeen said,
"Our frankness in admitting difficulties and relative ignorance in
regard to the variations and selections that led from certain dinosaurs
to birds cannot be used by any fairminded inquirer as an argument
against the idea of evolution. For hoe else could birds have arisen?"

   W.E. Swinton of the British Museum says, "With some imagination we
can link the Archaeopteryx with the forms that came later, but it
requires much speculation to see the origin of even the power of flight
this first known bird displays...None the less, nearly a century after
the publication of that monumental work [Darwin's Origin of the
Species], there are still monumental problems that remain to be settled
about the succession of life. This is especially true of the birds."

   *** Concerning the use of purely skeletal remains to show
evolutionary relationships:

   Evolution: A Theory in Crisis Dr. Michael Denton:

   pp177-178 To demonstrate that the great divisions of nature were
really bridged by transitional forms in the past, it is not sufficient
find in the fossil record one or two types of organisms of doubtful
affinity which might be placed on skeletal grounds in a relatively
intermediate position between other groups. The systematic status and
biological affinity of a fossil organism is far more difficult to
establish than in the case of the living form, and can never be
established with any degree of certainty. To begin with, ninety per
cent of the biology of and organism resides in its soft anatomy, which
is inaccessible in a fossil. Supposing, for example, all the marsupials
were extinct and the whole group was known only by skeletal remains-
would anyone guess that their reproductive biology was so utterly
different from that of placental mammals and in some wayseven more
complex?

   Modern birds differ greatly from reptiles in many physiological and
anatonomical characteristics, particularly, for example, in their
central nervous, cardiovascular and respiratory systems... but, because
information about the soft biology of a fossil form 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.

   One aspect of an organism's soft biology which can be sometimes
studied in a fossil is the gross morphology of the brain. This can be
done by preparing a cranial endocast of the intracranial cavity in the
skull which reveals the gross shape and outline of the brain. On the
evidence available from study of the cranial endocast of Archaeopteryx
, it would seem that its brain was essentially avian in all important
repects, exhibiting typical avian cerebral hemispheres and cerebellum
(the part of the brain involved in balance and the coordination of fine
motor activities), a part of the brain proportionally larger in birds
than in any other class of vertebrates and generally considered to be
an adaptation necessary for the control of the highly complex motor
activities involved in powered flight. The possession of an essentially
avian central nervous system lends furthur support to the idea based on
the basically modern form of its flight feathers and wing, that
Archaeopteryx was as capable of powered flight as a typical modern
bird. If Archaeopteryx was indeed capable of powered flight, might it
not also have possessed, of necessity, a fully avian heart, circulatory
and respiratory system to supply the vastly increased demand for oxygen
that occurs during powered flight? In other words, might it not have
been as avian as any other bird in all important anatomical and
physiological characteristics?

   Then there is the problem of convergence. Nature abounds in examples
of convergence: the similarity in the overall shape of whales,
ichthyosaurs and fishes; the similarity in the bone structure of the
flippers of the whale and an icthyosaur; the similarity of the
forelimbs of a mole and those of the insect, the molecricket; the great
similarity in the design of the eye in vertebrates and cephalopods and
the profound parallelism between the cochlea in birds and mammals. In
all the above cases the similarities, although very striking, DO NOT
IMPLY CLOSE BIOLOGICAL RELATIONSHIP.[authors emphasis, not mine- G.F.]

   pp 194, 195 It is possible to allude to a number of species and
groups such as Archaeopteryx, or the rhipidistian fish, which appear to
some extent intermediate. But even if such were intermediate to some
degree, there is no evidence that they are any more intermediate than
groups such as the living lungfish or monotremes which, as we have
seen, are not only tremendously isolated from their nearest cousins,
but which have individual organ systems that are not strictly
transitional at all. As evidence for the existence of natural links
between the great divisions of nature, they are only convincing to
someone already convinced of the reality of organic evolution.

   Scales to feathers

   The idea that feathers have some kind of ability to evolve from
reptilian scales is patently absurd. One source that was mentioned by
one person in support of the theory stated that the Archaeopteryx had
feathers and scales. the author could have been referring to the
bird-type scales on the feet which are found on all birds. But the
problem is, these scales found on the Archaeopteryx are bird scales and
are totally different from the reptile scales.

   The following are treatments on the feather/scale subject.

   "Adam and Evolution" Professor Michael Pitman copyright 1984.

   page 42 Consider reptilian scales, bird feathers and fur. The
evolutionist holds that feathers and fur have evolved, divergently from
scales. But can such different skin-coverings be called 'homologous'?
For example, a feather and a scale develop from different layers of
skin and follow different development paths; feather's greater
structural complexity must reflect a more complex genetic background.
Yet the first known feather is entirely feather- like, not scale-like.
The genes coding for each type of skin covering must contain a sequence
(subroutine) for keratin, because each is made primarily of a form of
keratin. Yet this subroutine could well be integrated into quite a
different overall set of genes. If so, how could we explain their
origin in terms of simple inheritance from a common ancestor?

   page 222 All birds have feathers: no other organisms do.
Archaeopteryx has feathers. There exists absolutely no evidence for the
evolution of feathers. The guess that DNA coding for scales 'must have'
changed to produce feathers is entirely unsubastantiated. No
intermediate scale-feather exists.

   Feathers are aerodynamic beauties. They are light, the shaft being
hollow, and quite different from the scales which are coded on to the
feet alone of birds. They grow from capsules called 'pin feathers' and
become lifeless when full grown. A feather from wing or tail is
composed of a shaft with branches, called barbs, arranged diagonally to
the left and right. The barbs have branches to the right and left
called barbules. These overlap neighboring barbules and are interlocked
to eachother by little hooks and eyelets.

   Some large feathers contain over a million barbules, with hooks and
eyelets to match, in perfect order. The feather is useless without this
interlocking mechanism which acts something like an automatic zip
fastener whose disturbance preening rearranges. When outstretched in
flight, the hooks cause the whole wing-assembly to form a continuous
sheet to catch the wind. The whole feather is a cohesive, elastic and
light structure, well designed to function as an air-resistant surface.
Sensory receptors record its precise position. Over both wings they
effect the continuous variations and fine adjustments of more than ten
thousand tiny muscles attached to the base of the feathers. Behold the
parts of a precision instrument of aerospace, unparalleled in design
and workmanship by human technology.

   Feathers are in no way frayed or modified scales. They even arise
from a different layer of skin cells. Whence evolved the pigment
mechanism for coloring and patterning both plumage and egg? In the
latter colours are laid down in the oviduct, in whose walls no pigment
has been found. This indicates that the organization of pigment and
pattern is coded into then avian DNA. By a megamutation?

   In Dr. Michael Denton's book "Evolution: A Theory in Crisis" he
addresses the problem of feathers arising out of scales in exquisite
detail. I will try to summarize his position as much as possible
because it runs for a number of pages.

   On the whole, however, even the most tentative schemes outlining a
sequence of events are seldom convincing. Take, for example, the
problem of the origin of birds. The flight feather of a bird is one of
the most beautiful and well known of all biological adaptations.

   [I won't go through the details of the feather since I covered that
in the Michael Pitman piece.-G.F.]

   ...It is almost universally accepted by evolutionary biologists that
birds evolved from reptiles, and that the feathers evolved from a
reptile's scale. Birds are certainly closely related to reptiles and it
is difficult to see what other group of living organisms could possibly
serve as hypothetical ancestors.

   By what sequence of events and through what kinds of transitional
states might the feather, the feathered airfoil or wing, and avian
flight have evolved? John Ostrum, an expert in this field, in a recent
article in the "American Scientist" refers to the two major traditional
scenarios.

   "Previous speculations on this question have produced two quite
different scenarios. Stated very simply these are that birds began to
fly "from the trees down"- or "from the ground up." The first is the
widely favored and very logical "arboreal theory,"...The second is the
often ridiculed and seemingly less probable "cursorial theory,"...

   One of the classic arboreal scenarios was developed by Gerhard
Heilman in his well known book "The Origin of Birds" Heilman, as an
advocate of the arboreal theory, envisaged a gliding stage preceding
the development of true powered flight. The original ancestor, he
suggests, was a terrestrial runner:

   [Here, Heilman's theory is quoted from his book. The basic outline
is as follows:

   -From terrestrial runner to arboreal climber leaping from branch to
branch and tree to tree and tree to ground.

   -Toes change so reptile/bird can grab branches

   -Pressure of air acts as stimulus to change scales to longer scales.

   -Friction of air causes scales to fray.

   -Gradually, longer horny processes become more and more feather-
like until perfect feather forms.

   -Feathers spread throughout whole body.

   -Intensive use of arms lengthens them creating more powerful muscles.

   -Breastbone halves ossify completely forming sight for muscles to
attach.

   -Metabolism increases, becomes warmblooded.


   Dr. Denton continues on and analyzes the two theories of flight-
from the ground up or from the tree down- going over the problems
associated with each none of which we will go into. We will concentrate
on the problem of scales to feathers. G.F.]

   pp208,209 According to Heilman the original impervious vane which
supported these pre-avian species as they glided was a set of "longish
scales developing along the posterior edge of the forearms and the side
edges of the flattened tale". Then he continues:

   By the friction of the air the outer edges became frayed, the
fraying gradually changing into still longer horny processes which in
the course of time became more and more featherlike.

   It is at this point, when the actual evolution of the feather is
envisaged, that Heilman's scheme begins to look particularly
implausible, for it is very difficult to understand what the adaptive
value of frayed scales would be to a gliding organism when any degree
of fraying would make the scales previous to the air, thereby
decreasing their surface area and lift capacity. All known organisms
which have adaptations for gliding among fish, frogs, reptiles, and
mammals present a continuous unbroken surface to the air. It would seen
reasonable to believe selection for gliding in a hypothetical pro-avis
would always tend to increase the impervious surface area of its wing
and decrease the tendency to fray...

   ...It is not easy to see how an impervious reptiles scale could be
converted gradually into an impervious feather without passing through
a frayed scale intermediate which would be weak, easily deformed and
still quite permeable to air. It is true that a feather is indeed a
frayed scale- a mass of keratin filaments- but the filaments are not a
random tangle but are ordered in an amazingly complex way to achieve
the tightly intertwined structure of the feather. Take away the
exquisite coadaptation of the components, take away the coadaptation of
the hooks and brabules, take away the precisely parallel arrangement of
the barbs on the shaft and all that is left is a soft pliable structure
utterly unsuitable to form the basis of a stiff impervious aerofoil.
The stiff impervious property of the feather which makes it so
beautiful an adaptation for flight, depends basically on such a highly
invlolved and unique system of coadaptive components that it seems
impossible that any transitional feather-like structure could possess
even to a slight degree the crucial properties. In the words of Barbara
Stahl, in "Vertebrate History: Problems in Evolution", as far as
feathers are concerned, "How they arose initially, presumably from
reptile scales, defies analysis."
