On Mon, 29 Jul 1996 2:26:55 -0500 (CDT), NIIIIIIICHOLAS MATZKE wrote:
[continued]
NM>On the same ground, I can say that a bird-like dino with a beak is
>at least suggestive of kinship between birds and dinos.
Agreed. But my point was about a particular "dino" Ornithomimus which
was too late to be an ancestor of birds.
NM>Other evidence was asked for, and here is what I know:
>Cretaceous waterbird fossils have been found that have a whole head
>of teeth.
This is hardly surprising since Archeopteryx was from the Jurassic,
ie. before the Cretaceous and it had "a whole head of teeth". But I
would like more details please, with a journal reference and quote,
if possible.
NM>Some dinos (T-rex was the example I heard) have large breastplates
>(necessary, in birds, for the attachment of wing muscles).
I have a diagram of "T-rex" and it doesn't seem to have a
particularly "large breastplate". And, like Ornithomimus, "T-rex"
arose in the late Cretaceous, so it cannot itself be ancestral to
birds:
"Toward the end of the Cretaceous the largest carnivores appeared.
The giant flesheating Tyrannosaurus measured about 15 metres (47
feel) in length with a height of 6 metres (19 feet) in bipedal pose."
("Encyclopaedia Britannica", Benton: Chicago, 15th edition, 1984,
7:570)
You might claim that Ornithomimus, "T-rex" and birds share a common
ancestor because they share some characters in common, but a chart I
have has the line that leads to Tyrannosaurusand the line that leads
to Ornithomimus branching way back in the Mid Triassic, about 140 MY
earlier, so it is a long bow to draw!
NM>Some ratites (ostriches, emus, and other ground birds) have
>vestigial claws on their wings.
I am not sure about "emus" but certainly some ratites and other
flying birds have wing-claws:
"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 Archaeopteryx." (Pitman M.,
"Adam and Evolution", Rider & Co: London, 1984, p224)
But this is not surprising since a bird's wing is on the same design
as an arm and a hand:
"The wing is a lengthened forelimb. As shown in colour, the arm
carries the short flight feathers. The wrist and three-fingered hand
together support the long primaries." (Peterson R.T., "The Birds",
Time/Life Books: Netherlands, 1964, p13)
Indeed birds have a "bastard wing" as Darwin pointed out is a digit:
"...in birds the "bastard-wing" may safely be considered as a
rudimentary digit" (Darwin C., "The Origin of Species", Everyman's
Library, 1967, J.M. Dent & Sons Ltd, London, p429)
It is on these "digits" that the wing-claws may appear:
"...The wing of a nestling hoatzin showing the presence of claws on
the first and second digits. The rudiment of the first digit in
modern birds supports the alula or bastard wing." (Carroll, R.L.,
"Vertebrate Paleontology and Evolution", 1988, W. H. Freeman & Co.,
p341)
NM>The fast moving, bipedal dinos were probably warm-blooded.
As stated previously all reptiles are "warm-blooded". The diference
is whether they can produce their heat internally:
"Mammals and birds produce body heat internally through biochemical
reactions - and are for this reason more correctly called endotherms
("inside heat") Reptiles, by contrast, rely on external sources of
heat to keep their bodies warm and are more correctly called
ectotherms ("outside heat")" (Norman D., "Dinosaur!", Boxtree:
London, 1991, p112)
Norman concedes there is evidence that most dinosaurs were
:
"Dinosaurs' apparent high activity and sophisticated behavior have
been interpreted as strong evidence that dinosaurs were endothermic
like modern mammals and birds. However, the evidence for this is far
from convincing for the majority of dinosaurs. The prevailing warm
and non-seasonal climate, combined with the unique aspects of
dinosaur physiology, allowed them for the most part to combine the
economies of an metabolism with a warm, constant internal temperature
which allowed complex control systems to develop, and circulatory and
respiratory systems allowing brisk physical activity." (Norman D.,
"Dinosaur!", Boxtree: London, 1991, p262)
However, he personally does not believe that they were endothermic:
"My preference, among the many current theories, is one which allows
the dinosaurs to prosper simply because they were reptiles, and is
linked to the environmental conditions which may have prevailed in
the Late Triassic world. It is probable that climatic conditions in
Late Triassic times were considerably warmer than at present. There
were certainly no ice-capped polar regions, and many areas of the
world appear to have been arid...the Late Triassic may well have
been; time of great potential for reptiles generally. If the world
was predominantly warm, dry, and sunny, conditions would have been
well suited to animals which relied on external warmth to maintain
their bod temperatures, were able to minimize water loss in arid
conditions and were able to live on a rather poor or patchy food
supply. Endothermic mammals which appeared at a similar time in the
fossilrecord share a set of attributes which may not have suited them
as well to the conditions of the time. Endothermy, though clearly
advantageous in some circumstances, brings with it considerable
costs: it requires a large intake of food as fuel to generate
internal body heat, and of large volumes of water which are released
by panting or sweating to keep cool, so that it is least effective in
hot conditions. Almost all we know about Late Triassic environments
seems to put mammals at a disadvantage and favor the standard
ectothermic reptile." (Norman D., "Dinosaur!", Boxtree: London,
1991, pp260-261)
However, he does concede that the small bird-like dinosaurs may have
developed some form of endothermy:
"The only groups which do not fit well with this model for dinosaur
success are the small, highly active dinosaurs exemplified by
Deinonychus. Dynamic small dinosaurs may well have been to some
extent endotherms, supplementing their body temperature by internal
heat generation in a manner similar to that of modern mammals and
birds - though precisely how similar this version of endothermy may
have been to that seen in mammals and birds today we will probably
never be able to say. This possibility of some smaller dinosaurs
being endotherms is given further support by the knowledge that
endothermic birds most probably originated from small, carnivorous
dinosaurs quite closely related to Deinonychus." (Norman D.,
"Dinosaur!", Boxtree: London, 1991, p262)
NM>Baby birds have a tooth they use to break out of their eggshell.
This is a necessity of getting out of an egg. IOW it's a corollary of
reproduction by eggs. Indeed, Darwin actually believed it was
independently acquired in snakes and birds:
"I can see no more difficulty in this, than in the unhatched young of
other birds acquiring the instinct to break through their own shells;
or than in young snakes acquiring in their upper jaws, as Owen has
remarked, a transitory sharp tooth for cutting through the tough
egg-shell. For if each part is liable to individual variations at
all ages, and the variations tend to be inherited at a corresponding
or earlier age,-propositions which cannot be disputed, -then the
instincts and structure of the young could be slowly modified as
surely as those of the adult; and both cases must stand or fall
together with the whole theory of natural selection." (Darwin C.,
"The Origin of Species", 6th Edition, 1872, Everyman's Library, J.M.
Dent & Sons Ltd: London, 1967 reprint, p240).
NM>All of this together with Archyoptryx still not proof, by any
>means, and is certainly not showing "how a bird could evolve from a
>dino by 100% naturalistic proccesses" - an unattainable goal for ANY
>natural process, if you take it to mean knowing the changes in
>genetic code for each member of each ancestral population, the
>reason for the spread of the change, etc.
Agreed. Darwinian evolution cannot prove its central thesis that all
living things descended from a common ancestor by purely natural
processes. It is simply the best *naturalistic* explanation
available:
"A theory of biological origins that is in a general way like
Darwinism follows fairly straightforwardly from the proposition that
God is an illusion and nature is therefore all that exists. If
nature is all there is, how did complex things like ourselves come
into existence? Without a satisfying answer to that question,
naturalism is a nonstarter. The most appealing answer is that there
was a process of evolution from simple to complex and that there
exists a process for generating adaptive complexity that does not
require direction from a preexisting intelligence. Darwinian
selection is simply the most plausible candidate for that process
that has ever been suggested." (Johnson P.E., "Reason in the
Balance", InterVarsity Press: Downers Grove Ill., 1995, pp16-17)
NM>We can make pretty good guesses on some issues - the evolution of
>flight or the modification of a lung are certainly not on the same
>level of difficulty as the evolution of an eye, and THAT can be
>reasonably explained by naturalistic processes (although deciding
>the exact path for each eye in each lineage is probably beyond our
>powers).
I would like to see your "pretty good guesses on...the modification
of a lung", ie. the avian lung. Denton says:
"In addition to the problem of the origin of the feather and flight,
birds possess other unique adaptations which also seem to defy
plausible evolutionary explanations. One such adaptation is the
avian lung and respiratory system. In all other vertebrates the air
is drawn into the lungs through a system of branching tubes which
finally terminate in tiny air sacs, or alveoli, so that during
respiration the air is moved in and out through the same passage. In
the case of birds, however, the major bronchi break down into tiny
tubes which permeate the lung tissue. These so-called parabronchi
eventually join up together again, forming a true circulatory system
so that air flows in one direction through the lungs.
This unidirectional flow of air is maintained during both inspiration
and expiration by a complex system of interconnected air sacs in the
birds body which expand and contract in such a way so as to ensure a
continuous delivery of air through the parabronchi. The existence of
this air sac system in turn has necessitated a highly specialized and
unique division of the body cavity of the bird into several
compressible compartments. Although air sacs occur in certain
reptilian groups, the structure of the lung in birds and the overall
functioning of the respiratory system is quite unique. No lung in
any other vertebrate species is known which in any way approaches the
avian system. Moreover, it is identical in all essential details in
birds as diverse as humming birds, ostriches and hawks.
Just how such an utterly different respiratory system could have
evolved gradually from the standard vertebrate design is
fantastically difficult to envisage, especially bearing in mind that
the maintenance of respiratory function is absolutely vital to the
life of an organism to the extent that the slightest malfunction
leads to death within minutes. Just as the feather cannot function
as an organ of flight until the hooks and barbules are coadapted to
fit together perfectly, so the avian lung cannot function as an organ
of respiration until the Parabronchi system which permeates it and
the air sac system which guarantees the parabronchi their air supply
are both highly developed and able to function together in a
perfectly integrated manner.
Moreover, the unique function and form of the avian lung necessitates
a number of additional unique adaptations during avian development.
As Dunker, one of the world's leading authorities in this field,
explains, because, first, the avian lung is fixed rigidly to the body
wall and cannot therefore expand in volume and, second because of the
small diameter of the lung capillaries and the resulting high surface
tension of any liquid within them, the avian lung cannot be inflated
out of a collapsed state as happens in all other vertebrates after
birth In birds, aeration of the lungs must occur gradually and starts
three to four days before hatching with a filling of the main
bronchi, air sacs and parabronchi with air. Only after the main air
ducts are already filled with air does the final development of the
lung, and particularly the growth of the air capillary network, take
place. The air capillaries are never collapsed as are the alveoli of
other vertebrate species, rather, as they grow into the lung tissue,
the parabronchi are from the beginning open tubes filled either with
air or fluid (which is later absorbed into the blood capillaries).
In attempting to explain how such an intricate and highly specialized
system of correlated adaptations could have been achieved gradually
through perfectly functional intermediates, one is faced with the
problem of the feather magnified a thousand times. The suspicion
inevitably arises that perhaps no functional intermediate exists
between the dead-end and continuous through-put types of lung. The
fact that the design of the avian respiratory system is essentially
invariant in ALL birds merely increases one's suspicion that no
fundamental variation of the system is compatible with the
preservation of respiratory function...The avian lung and the
feather bring us very close to answering Darwin's challenge:
`If it could be demonstrated that any complex organ existed which
could not possibly have been formed by numerous, successive, slight
modifications, my theory would absolutely break down.' (Darwin C.,
"The Origin of Species", 6th edition, 1872, Collier Books: NY, 1962,
p182)
(Denton M., "Evolution: A Theory in Crisis", Burnett Books: London,
1985, pp210-213)
[continued]
God bless.
Steve
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