Natural Science Forum / Biology / Paleontology / June 2006

http://members.iinet.net.au/~sejones/PoE/pe13anml.html#nmlsmlslwhltrnstn

4. Land mammal-whale transition
Evolution has a major problem with the land mammal to whale transition. The
creationist zoologist, Douglas Dewar,
has summarised the immense changes involved in such a transition:

"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.
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. Be it noted that there is no stage
intermediate between being born and
suckled under water and being born and suckled in the air. At the same time
various other anatomical
changes have to take place, the most important of which is the complete
transformation of the tail region.
The hind part of the body must have begun to twist on the fore part, and
this twisting must nave continued
until the sideways movement of the tail developed into an up-and-down
movement. While this twisting went
on the hind limbs and pelvis must have diminished in size, until the latter
ceased to exist as external limbs in
all, and completely disappeared in most, whales." (Dewar D., 1938, pp.23-24)
Descriptions by evolutionists give some idea of the enormity of these
changes: "Evolution had produced a
metamorphosis that Ovid would have loved: it had transformed away their
legs, given them flukes on their tail,
had put their noses on top of their heads" (Zimmer, 2001, p.136); "The
lineage that gave rise to dolphins,
whales, and porpoises went through a transformation just as staggering as
the one that brought vertebrates on land
in the first place" (Zimmer, 1998, p.6).

Paleontologists "cannot even reasonably begin to entertain the hypothesis of
a long, unrecorded interval of
diversification," for whales (Stanley, 1979, p.69). But they had thought
that "the extent of the change
involved in the transformation of a terrestrial mammal into a completely
oceanic one was so great that the
process must have begun at least as long ago as the early Paleocene (~60
mya) and possibly even before that
time, at the end of the Cretaceous period (~65 mya) (Stahl, 1985, p.486).
Then "the oldest specimens [of
whales], dating back more than 40 million years, were fundamentally like
whales today," with "flippers, and
no back legs" (Zimmer, 2001, p.136).

However, with the discovery of even earlier whale fossils the time frame for
this transition has shrunk to only
10-12 million years (Carroll, 1997, p.336; Zimmer, 1995a), or even less
(Wesson, 1991, pp.51-52)!
But since such changes to be preserved must be "locked up"' by speciation
(Gould & Eldredge 1993), that
requires that each major transformation be a new species (or
"chronospecies"). Since the average mammal
species of that Cenozoic Era typically last a million years, "we have only
ten or fifteen chronospecies to
align, end-to-end, to form a continuous lineage connecting our primitive
little mammal with a ... whale"
(Stanley, 1981, p.93). But, "this is clearly preposterous. ... 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 ...
whale" (Stanley, 1981, pp.93-94)!

Adding to the problem is that large mammals, including whales, are limited
in their capacity to change
through random mutations and natural selection, factors including: "long
generation spans (the time between
birth and the ability to give birth)" and "low numbers of progeny produced
per adult" (Ross, 1998, pp.51-
52).

A recent discovery of a 14 myo baleen whale fossil, Eobalaenoptera harrisoni
may create further
problems for evolution by suggesting that "almost-modern-looking whales
lived considerably further back in
time than scientists realized" (ABCNews, 2004a) [to be continued] [top]