In a message dated 9/24/2000 3:21:30 PM Pacific Daylight Time,
sejones@iinet.net.au writes:
I would like to stop and address in more detail SJ's comments about whale
evolution. I would first like to invite Steve to check out James Acker's
review of
"The Emergence of Whales: Evolutionary Patterns in the Origins of Cetacea
(Advances in Vertebrate Paleontology) edited by J.G.M. Thewissen"
I have posted the links to the relevant chapters.
<< Here are some of the problems for RM&NS in the land mammal-whale
transition (which I accept probably happened BTW but not by RM&NS):
1. the changes required:
"Let us notice what would be involved in the conversion of a land
quadruped into, first a seal-like creature and then into a whale. The
land animal would, while on land, have to cease using its hind legs
for locomotion and to keep than permanently stretched out
backwards on either side of the tail and to drag itself about by using
its fore-legs. During its excursions in the water, it must have
retained the hind legs in their rigid position and swum by moving
them and the tail from side to side. As a result of this act of self
denial we must assume that the hind legs eventually be came pinned
to the tail by the growth of membrane. Thus the hind part of the
body would have become likes that of a seal. >>
Tail evolution is problematic since the tail is not preserved in the fossil
record but as James Acker points out:
" Because the flukes are soft tissue, fossil preservation has not occurred.
BUT (lest ye creationists take heart) modern cetaceans have associated
features that can be compared to fossils "to indicate the course of fluke
evolution"."
http://x72.deja.com/[ST_rn=ps]/getdoc.xp?AN=632802532
So what is known ?
"4. Evolution
Pay attention now. Because "the ancestors of cetaceans were terrestrial",
they didn't have flukes before adopting a semi-aquatic or
mostly aquatic existence. 2 questions: how did the flukes evolve, and what
were the transitional stages and levels of performance.
Guess what? There isn't much information to go with regard to archaeocete
flukes (or even the caudal ends of the spine). But
skeletons and fin impressions of mosasaurs, particularly a lower Triassic
ichthyosaur Chensaurus chaoxianensis (my guess is
that this was found in China) allowed investigators to look at the skeletal
transformation accompanying changing swimming styles.
I'll give the reference for this one:
Motani, R., You, H., and McGowan, C., 1996. Eel-like swimming in the
earliest ichthyosaurs. Nature, 382, 347-348. I invite a reader
to go look this one up and comment on it.
So what is Fish to do? A. Examine ontogenetic information, and B. use
model specimens. Similarities between ontogenetic and
phylogenetic sequences reflect a possible developmental pathway. It's been
done before for the mammalian middle ear and
neocortex. (Rowe, T., 1996, Science, 273, 651-654).
Models of swimming performance in modern species can be used as analogues of
primitive intermediate (!!) forms, allowing
examination of performance characteristics, leading to a mechanically
plausible evolution scenario. The key is the mechanics of
swimming, not
the actual organisms examined. Also already done before
(Lauder, G.V., "On the Inference of Function from Structure, pp. 1-18 in
"Functional Morphology in Vertebrate Paleontology" edited by
J.J. Thomason, Cambridge University Press)."
James continues to describe additional information. It would be interesting
to get the actual book.
Having reached this
<< stage, the creature in anticipation of a time when it will give birth
to
its young under water, gradually develops apparatus by means of
which the milk is forced into the mouth of the young one, and,
meanwhile a cap has to be formed round the nipple into which the
snout of the young one fits tightly, the epiglottis and laryngeal
cartilage become prolonged upwards to form a cone-shaped tube,
and the soft palate becomes prolonged downwards so as tightly to
embrace this tube, in order that the adult will be able to breathe
while taking water into the mouth and the young while taking in
milk. These changes must be effected completely before the calf can
be born under water. >>
Nursing again is a problematic issue as far as fossil preservation is
concerned but what is know?
http://x70.deja.com/getdoc.xp?AN=651912269
Be it noted that there is no stage intermediate
<< between being born and suckled under water and being born and
suckled in the air. >>
See above but also:
"
This is a fallacious problem. The whale fossils
even show that some changes occurred faster than others (in particular,
auditory changes, which may have been related to prey
acquisition, occurred more rapidly than other changes). The blowhole did
not have to be in its modern position for the animals to
breathe (think of all the other mostly aquatic mammals that spend months at
sea or in the water). Manatees nurse in-water
despite not having the specialized nipple: the female rolls onto her side
and the pup nurses at a teat that is located under the front
fins. In order to accomplish nursing the teat and the pup's mouth must be
in the air, but not the whole animal.
So these changes do not have to be simultaneous. Sea
lions, seals, sea elephants, and walruses are all clearly better suited for
water than for land, but they retain a link to the
land because of reproductive requirements or insulation requirements. But
they do not appear to be endangered due to the need
for some terrestrial capability." James Acker Ibid
<< Maybe this is an example of what Gould & Eldredge had in mind when
they wrote:
"At the higher level of evolutionary transition between basic
morphological designs, gradualism has always been in trouble,
though it remains the "official" position of most Western
evolutionists. Smooth intermediates between Bauplane are almost
impossible to construct, even in thought experiments." (Gould S.J.
& Eldredge N., "Punctuated equilibria: the tempo and mode of
evolution reconsidered," Paleobiology, 1977, Vol. 3, pp.115-147,
p.147)
>>
Hence the formation of the punctuated equilibrium hypothesis. Note again the
early date. Whale evolution has undergone a lot of exciting advancements in
the last decade(s).
<< 2. the timeframe in the fossil record (i.e. ~10 million years):
"Today, our more detailed knowledge of fossil mammals lays
another knotty problem at the feet of gradualism. Given a simple
little rondentlike animal as a starting point, what does it mean to
form a bat in less than ten million years, or a whale in little more
time? We can approach this question by measuring how long
species of mammals have persisted in geological time. The results
are striking; we can now show that fossil mammal populations
assigned to a particular Cenozoic lineage typically span the better
part of a million years without displaying sufficient net change to be
recognized as a new species. The preceding observations permit us
to engage in another thought experiment. Let us suppose that we
wish, hypothetically, to form a bat or a whale without invoking
change by rapid branching. In other words, we want to see what
happens when we restrict evolution to the process of gradual
transformation of established species. If an average chronospecies
lasts nearly a million years, or even longer, and we have at our
disposal only ten million years, then we have only ten or fifteen
chronospecies to align, end-to-end, to form a continuous lineage
connecting our primitive little mammal with a bat or a whale. This
is clearly preposterous. Chronospecies, by definition, grade into
each other, and each one encompasses very little change. A chain of
ten or fifteen of these might move us from one small rodentlike
form to a slightly different one, perhaps representing a new genus,
but not to a bat or a whale!" (Stanley S.M., "The New Evolutionary
Timetable," 1981, pp.93-94)
>>
Again a bit dated as far as whale evolution is concerned. Stanley is also
comparing phyletic gradualism with punctuated equilibrium.
Is this a problem for evolutionary theory?
<< 3. the driver in RM&NS is supposed to be competition, but competition
would be *reduced* in a vast new ecological niche like an ocean.
>>
I mentioned before that the first 'whales' were likely coastal dwellers.
Pakicetus and Nalacetus, Ypresian (53-45 mya)
Ambulocetus natans, Lutetian (45-39 mya)
Rodhocetus /Indocetus, Lutetian (45-39 mya)*
Georgiacetus vogtlensis, Bartonian (39-34 mya)
Dorudon atrox /Zygorhiza kochii, Bartonian to eary Priabonian
(~ 36-30 mya).
*Three notes: 1. The formation in which Ambulocetus natans was found is
characteristic of "tidal areas with a strong freshwater
influence" while the formations that yielded Rodhocetus and Indocetus are
coastal marine deposits with perhaps some freshwater influence.
2. The formation in which Ambulocetus was found is about 3 million years
older than that for Rodhocetus and Indocetus.
Ambulocetus was essentially found in the earliest Lutetian, while Rodhocetus
is mid-Lutetian.
3. I've been quoting an IUGS dating scheme, but there's an alternative with
an offset. A geologist is invited to explain the
discrepancy. The alternative time ranges are
Ypresian, 55-50 mya
Lutetian, 49-42 mya.
http://x57.deja.com/getdoc.xp?AN=652946344.2
<< 4. it is numbers of *offspring* which is important to RM&NS, but larger
mammals have long comparatively gestation and generation times and small
numbers of offspring:
"The presenters could not have picked any more vulnerable
"evidences" than the whale species. The whale's capacity for natural
process change is severely limited by ... 2) long generation spans
(the time between birth and the ability to give birth); 3) low number
of progeny produced per adult; ... these factors severely limit a
species' capacity to change, or even to adapt to change, through
mutations and natural selection." (Ross H.N., "Creation on the `Firing
Line'", Facts & Faith, First Quarter 1998.
http://www.reasons.org/resources/FAF/98q1faf/98q1aisi.html)
>>
And yet they managed to evolve. So there is a problem with Ross's argument
here.
James Acker:
" It doesn't appear to have been a problem. In terms of numbers, they have
been severely reduced by whaling, and were far more
prolific before mankind slaughtered them. As for reproduction, they are
related to terrestrial ungulates, and I know, for example, that
deer can have one or two fawns a year. Cows probably can, too. So the low
reproduction rate now may be a consequence of
aquatic existence and the necessity for precocial development in the womb so
that they can swim when they are born. Not a
requirement for terrestrial or amphibious ancestors. "
http://x59.deja.com/getdoc.xp?AN=651912269.2
<< 5. vast numbers of intermediates in the fossil record (not just a handful)
are needed to establish RM&NS:
"Darwin's insistence that gradual evolution by natural selection
would require inconceivable numbers of transitional forms may
have been something of an exaggeration but it is hard to escape
concluding that in some cases he may not have been so far from the
mark. >>
See http://x56.deja.com/getdoc.xp?AN=665479029
Quote]
I have attempted to show that the geological record is
extremely imperfect; that only a small portion of the globe
has been geologically explored with care; that only certain
classes of organic beings have been largely preserved in a
fossil state; that the number both of specimens and of
species, preserved in our museums, is absolutely as nothing
compared with the incalculable number of generations which
must have passed away even during a single formation; that,
owing to subsidence being necessary for the accumulation of
fossiliferous deposits thick enough to resist future
degradation, enormous intervals of time have elapsed between
the successive formations; that there has probably been more
extinction during the periods of subsidence, and more
variation during the periods of elevation, and during the
latter the record will have been least perfectly kept; that
each single formation has not been continuously deposited;
that the duration of each formation is, perhaps, short
compared with the average duration of specific forms; that
migration has played an important part in the first appearance
of new forms in any one area and formation; that widely
ranging species are those which have varied most, and have
oftenest given rise to new species; and that varieties have at
first often been local. All these causes taken conjointly,
must have tended to make the geological record extremely
imperfect, and will to a large extent explain why we do not
find interminable varieties, connecting together all the
extinct and existing forms of life by the finest graduated
steps.
[End Quote - CR Darwin, Origin of Species, 1st ed., pp.340-341]
and
http://x52.deja.com/getdoc.xp?AN=563484601
Also our friend Wesley
http://x63.deja.com/getdoc.xp?AN=543914628.1
Take the case of the gap between modern whales and land
<< mammals. All known aquatic or semi-aquatic mammals such as
seals, sea cows (sirenians) or otters are specialized representatives
of distinct orders and none can possibly be ancestral to the present-
day whales. To bridge the gap we are forced therefore to postulate
a large number of entirely extinct hypothetical species starting from
a small, relatively unspecialized land mammal like a shrew and
leading successfully through an otter-like stage, seal-like stage,
sirenian-like stage and finally to a putative organism which could
serve as the ancestor of the modern whales. >>
We know now much more than in 1985
[...]
Even Denton seems to have changed his mind (See Darwinism Defeated? pp
144-145). Although Denton does not describe the whale evolution he does
address the gaps in fossil record.
http://home.wxs.nl/~gkorthof/kortho29.htm
<<
Denton M.J., "Evolution: A Theory in Crisis," 1985, pp.172,174)
>>
http://www.infidels.org/library/modern/mark_vuletic/denton.html
Lamoureux also addresses Johnson's description of the whale evolution. More
on that later when I review issues raised in the book.
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