On Thu, 11 Jul 1996 23:40:20 -0500 (CDT), NIIIIIIICHOLAS MATZKE wrote:
[continued]
>SJ>...the bipedality and bird- like appearance of Iguanodon were
>entirely vindicated by the discovery of complete skeletons of
>Iguanodon at Bernissart in Belgium...when looked at in detail the
>feet and legs are extremely bird-like in shape; and - most
>importantly - the bones of the hips are arranged very much like
>those of birds (for this is an ornithischian or "bird-hipped"
>dinosaur) confirming Huxley's views as well." (Norman D.,
>"Dinosaur!", Boxtree: London, 1991, p93)
>
>The real truth is Darwinists do not know which dinosaur group
>birds came from. This is admitted by Norman:
>
>"Take your pick. Any final judgment on the matter is based on
>personal preference for particular idea or theory. ...." (Norman
D., "Dinosaur!", Boxtree: London, 1991, p199)"
NM>I don't know how relevant Huxley is to all of this...he didn't
>have all of the evidence we do. It is true that the bird-hipped
>dinosaurs have hips and sometimes other traits that are somewhat
>birdlike (especially earlier ones; by the Cretaceous, most
>"bird-hipped" dinos had hips that didn't look much like bird hips
>(National Geographic, Jan 93, p. 200).
T.H. Huxley was one of the greatest anatomists of all time and an
expert in dinosaurs. Norman in 1991 is still referring to his
original view of birds being from the ornithischians as receiving
some confirmatrion by more modern discoveries.
NM>The point is that animals are
>classified by a large number of traits that are shared by a large number of
>animals and that are displayed no matter what ecological role the creature
>plays. This is the key to overcoming the problems of convergence. One, or
>several, traits may converge, but traits that are RESISTANT to change due to
>adaption to ecological roles are best for determining kinship. I agree that we
>could classify animals into those with flippers, wings, feet, etc; but we would
>be lumping together animals with many contrasting traits for each one that is
>the same. Molecular traits are the ultimate in resistance to change due to
>adaptation: many mutations in DNA are not expressed at all, so any similarity
>between the DNA sequences in two species cannot be due to convergence from
>evolutionary pressure. The similarity must be due to luck (extremely unlikely)
>or kinship. The fact that molecular evidence independantly correlates
>conclusions drawn from physical nonadaptive traits in almost all cases (Dawkins
>porcupines may be a noteworthy exception where DNA sequencing is forcing
>revision of old views) is encourages me that taxonomists, for the most part,
>have been doing it right, for the most part, for most of the time (which is
>really all that you can ask of a scientist).
OK. Please publish the molecular evidence that shows which group of
dinosaurs birds came from! :-)
SJ>"I agree that "this dinosaur is also displaying bird-like traits"
>ie. it has a beak. But so does an octupus."
NM>See above - an octopus shares none of the "dozen skeletal
>characteristics" (Jan. 93 National Geographic, p. 8) that identify
>dinosaurs, while I bet that birds share a number of them.
Agreed. But my point was that any particular trait is not conclusive
for common ancestry of that trait. This is particularly so when the
first appearance of the dinosaur in question post-dated the earliest
birds.
SJ>"And as for "lizard hips", I cannot see that is "evidence of
>kinship" of dinosaurs and birds."
NM>I said this too fast, sorry. Some dinos in the "lizard-hipped"
>catagory have hips and other skeletal traits that look a lot like
>bird skeletal characteristics, enough so that Archeopteryx was been
>misidentified as a "lizard-hipped" dinosaur instead of a bird in case
>where the feathers were poorly preserved.
Yes. But see on iguandodon. It was a bird-hipped dinosaur and also
had many "skeletal traits that look a lot like bird skeletal
characteristics". The problem is that, as Carroll points out, they
are *too much* like "bird skeletal characteristics" to be ancestral
to birds:
"When Archaeopteryx was first described, it was thought to be closely
related to dinosaurs. As that group became better known, it appeared
that all dinosaurs were too specialized to be directly ancestral to
birds. In his very influential book, Heilmann (1926) argued that
Archaeopteryx must have evolved from more primitive archosaurs, the
Triassic thecodonts. There are no features of primitive thecodonts
that preclude them from being the ultimate ancestors of both dinosaurs
and birds, but no thecodonts can be demonstrated as sharing a unique,
common ancestry with birds. The features that they share are all
primitive for archosaurs in general. Walker (1972), Martin, Stewart,
and Whetstone (1980), and Martin (1983) showed that there are some
characters of birds that are shared with crocodiles, but there is no
evidence that they are uniquely shared with a common ancestor of these
groups. The high degree of specialization of the entire skull of
early crocodiles makes it difficult to accept that similarities of
particular aspects of the quadrate and middle ear were the result of
an immediate common ancestry. Ostrom (1975b) demonstrated that many
specialized aspects of the skeleton of Archaeopteryx are uniquely
shared with small theropods and with no other groups of archosaurs.
These characters include the structure of the forelimbs and hind
limbs, the shoulder girdle, and skull...There is a great overall
similarity to Compsognathus, but this genus is too late in time (as a
direct contemporary of Archaeopteryx) and too specialized in the
reduction of the the manus to two digits. No other adequately known
theropod appears to be an appropriate ancestor." (Carroll, R.L.,
"Vertebrate Paleontology and Evolution", 1988, W. H. Freeman & Co.,
p340)
SJ>"My other points was that: a) there was nothing new about
>Ornithomimus having a beak; and b) it is too recent to be ancestral
>to birds. To the extent that this is not told to the general reading
>public, it is "propaganda"."
NM>I guess you're right. Maybe what was "new" was that the
>Ornithomimus discovered was "perfectly preserved", leaving it beyond
>question that it was a birdlike dino with a beak. Perfect skeletons
>are very, very rare - until recently, the most famous dino, T-rex,
>was only known from 3 complete skeletons.
Perhaps. But was there any doubt that Ornithomimus had a beak before?
I would have thought that there wouldn't be much problem with beaks
fossilising.
NM>On b), I wholeheartedly admit that this dino is not ancestral to
>birds. The fault, I am certain, lies with the press (which
>condenses everything into soundbites), and not with the
>paleontologist, who would know this.
Hmmmm. How convenient to always blame the press, while reaping the
benefit in public interest and funding! :-) Do scientists so
misquoted ever write in to the Editor and correct the
misunderstanding? I doubt it.
NM>However, the article does not SAY that Ornithomimus was ancestral
>to birds: it says that Ornithomimus (whether completely new or not,
>I don't know) is evidence that birds descended from DINOSAURS.
How is it "evidence that birds descended from dinosaurs" when: a) it
is not even certain they did (see Carroll and Norman above); and b)
this dinosaur Ornithomimus is too late?
NM>I'll repeat, for emphasis, since this is just about the most
>common mistake I see in understanding evolution: FOSSILS CAN BE
>EVIDENCE OF DESCENT OF ONE GROUP FROM ANOTHER WITHOUT THEMSELVES
>BEING DIRECT ANCESTORS OF THAT GROUP. Sorry to shout, but if this
>was better understood (and if the press mentioned it specifically in
>news articles, like they should have in this one), then a whole lot
>of arguments between pro and anti evolutionists would go away. Do
>you agree with this, Stephen?
No "mistake" is being made here by me. I am well aware that "fossils
can be evidence of descent of one group from another without
themselves being direct ancestors of that group". But in the case in
point, ie. Ornithomimus being evidence that birds have descended
from dinosaurs, I cannot see the connection.
NM>A quick example or two to illustrate: a platypus, an egg-laying
>mammal (monotreme) is an evidence of mammals' descent from reptiles.
>The platypus has many other traits intermediate between reptile and
>mammal (partially warm-blooded, etc). Thus, the platypus descended
>from a reptile-like mammal, and the reptile-like mammal descended
>from, obviously, reptiles.
That the platypus has some features common to reptiles (clavicle,
reproductive system) and other features common to mammals (fur,
warm-blooded, mammary glands, mammalian ear and jaw bones) is
evidence of descent from a primitive pre-marsupial/pre-placental
mammal-like reptile:
"The presence of premammalian characters in platypuses does not
brand them as inferior or inefficient. But these characters do
convey a different and interesting message. They do signify an
early branching of monotreme ancestors from the lineage leading
to placental mammals. This lineage did not lose its reptilian
characters all at once, but in the halting and piecemeal fashion
so characteristic of evolutionary trends. A branch that split
from this central lineage after the defining features of mammals
had evolved (hair and an earful of previous jawbones, for
example) might retain other premammalian characters (birth from
eggs and an interclavicle) as a sign of early derivation, not a
mark of backwardness." (Gould S.J., "To Be A Platypus", "Bully
for Brontosaurus", Penguin: London, 1992, p276)
But the platypus actually represents a problem for Darwinian
evolution. For example:
1. The intermediate features are fully formed and not
transitional:
"Another classic example of an intermediate type is the
egg-laying mammals, the monotremes such as the duck billed
platypus. In laying eggs the monotremes are reptilian, but in
their possession of hair, mammary glands, and three ear ossicles
they are entirely mammalian. Undoubtedly, if the various
anatomical and physiological systems in the lungfish and the
monotremes were all strictly transitional between fish and
amphibia and between reptiles and mammals respectively, then the
case for them being genuine transitional types would be far
clearer...The biology of the monotremes is similar. Again, where
they are reptilian in, for example, the reproductive system and
in the structure of their eggs, they seem almost fully reptilian,
while where they are mammalian, as for example in the
construction of their middle ear, or in the possession of hair,
they are fully mammalian. Instead of finding character traits
which are obviously transitional we find them to be either
basically reptilian or basically mammalian, so that although the
monotremes are a puzzle in terms of typology they afford little
evidence for believing that any of the basic character traits of
the mammals were achieved gradually in the way evolution
envisages." (Denton M., "Evolution: A Theory in Crisis",
Burnett Books: London, 1985, pp109-110)
2. The molecular biology of monotremes is nearer placental mammals
than marsupials, whereas Darwinism would predict the reverse:
"As regards sequence data, the DNA complement of monotremes is
nearer (with 97-98 per cent) that of placental mammals than
marsupials (with 81-94 per cent)." (Pitman M., "Adam and
Evolution", Rider & Co: London, 1984, p210)
3. The platypus supposedly originated 150 million years ago:
"The reptilian characteristics of the platypus led scientists to
conclude that it is descended from a link between the reptiles
and mammals of 150 million years ago. At any rate, it is a
highly specialized survivor of an ancient line." (Moore R.,
"Evolution", Time/Life Books: Netherlands, 1964, pp60- 61)
but its first appearance in the fossil record is only 2 million years
ago:
"The Monotremata (monotremes) are a distinctive order of
primitive mammals, the only surviving members of the subclass
Prototheria...Only two monotreme types, the platypus
(Ornithorhynchus anatinus, family Ornithorhynchidae) and the
echidnas, or spiny anteaters (Tachyglossus aculeatus and
Zaglossus bruijni, family Tachyglossidae), are known. The
earliest monotreme fossils known come from the Australian
Pleistocene (2,000,000 or more years ago), and they are
essentially the same as the living forms..." ("Encyclopaedia
Britannica", Benton: Chicago, 15th edition, 1984, 12:384).
4. If the platypus did originate 150 million years ago, then it has
continued unchanged down to the present, despite immense changes to
the environment:
"One more point must be mentioned. There are in nature certain
forms that have existed unchanged through enormous stretches of
time; e.g., the platypus, the little brachiopod Lingula, the
oyster, the opossum, the ginkgo tree, the Australian lungfish,
and the recently discovered fish called Latimeria. These are
known as "living fossils" or "persistent types." They puzzle and
annoy the evolutionists, who feel obligated to explain why, in a
world of change, these forms continue in their old placid way
without either changing or becoming extinct. In hundreds of
millions of years there must have been changes in climate,
changes in the environment, new enemies, new parasites, new
diseases. Yet these creatures, without showing any special
virtues or abilities, continue unchanged....The Darwinists are
stumped. They cannot explain extinction or survival, although
these phenomena are the essence of evolution." (Macbeth N.,
"Darwin Retried: An Appeal to Reason", Garnstone Press: London,
1978 (reprint), pp121-122)
Indeed, the platypus may be a badly chosen example in this debate
about whether Ornithomimus' beak was evidence of birds descending
from dinosaurs. The platypus has a beak too, that was so bird-like
that early anatomists thought it was a stitched on duck's bill:
"The platypus sports an unbeatable combination for strangeness:
first, an odd habitat with curiously adapted form to match second,
the real reason for its special place in zoological history-its
enigmatic melange of reptilian (or birdlike), with obvious mammalian,
characters. Ironically, the feature that first suggested
premammalian affinity-the "duckbill" itself-supports no such meaning.
The platypus's muzzle (the main theme of this column) is a purely
mammalian adaptation to feeding in fresh waters, not a throwback to
ancestral form-although the duckbill's formal name embodies this
false interpretation: Ornithorhynchus anatinus (or the ducklike bird
snout). Chinese taxidermists had long fooled (and defrauded)
European mariners with heads and trunks of monkeys stitched to the
hind parts of fish-one prominent source for the persistence of
mermaid legends. In this context, one can scarcely blame George Shaw
for his caution in first describing the platypus (1799):
`Of all the Mammalia yet known it seems the most extraordinary in its
conformation, exhibiting the perfect resemblance of the beak of a
Duck engrafted on the head of a quadruped. So accurate is the
similitude, that, at first view, it naturally excites the idea of some
deceptive preparation....On a subject so extraordinary as the
present, a degree of scepticism is not only pardonable but laudable;
and I ought perhaps to acknowledge that I almost doubt the testimony
of my own eyes with respect to the structure of this animal's beak;
yet must confess that I can perceive no appearance of any deceptive
preparation...nor can the most accurate examination of expert
anatomists discover any deception." (Gould S.J., "To Be A Platypus",
"Bully for Brontosaurus", Penguin: London, 1992, p271)
NM>Humans, bats, whales, cows and other placental mammals don't
>share many traits with reptiles, but the fact that there is a mammal
>that does share those traits lets us conclude that they are
>descended from a reptile-like mammal also. Note that I did NOT say
>that all placental mammals are descended from platypus's/platypus'
>(platypi??). Placentals and monotremes share a common ancestor.
See above. The actual first appearance of monotremes in the fossil
record is only 2 million years ago, whereas mammal-like reptiles
appeared 150 million years ago. On the basis of this, all that can be
claimed is that monotremes share some features in common between
mammals and reptiles..
[continued]
God bless
Steve
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| 3 Hawker Avenue / Oz \ sjones@iinet.net.au |
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