> Thanks for the update, Keith. You speak of the "range of environments" as if
> it were an established fact. What are they? Wetlands? What else is there?
> I would appreciate any references you have on these points. Moreover, so
> what? If there were in fact a range of environments, would the animal not
> stay in the one it was best adapted to and ignore the rest? Or are you
> suggesting that these environments appeared sequentially and that the animal
> was forced by necessity to adapt to the current one?
Lets use the example of whale evolution. There are now 26 fossil species
of primitive whales known that have been assigned to four families: the
Pakicetidae, Ambuloceticae, Remingtonocetidae, and Protocetidae. These
show a really amazing progression. Not only do the fossils occur in the
correct chronological order, but they are found in progressively more
marine settings. The most primitive group, the pakicetids, occur
exclusively in river channel deposits. The ambulocetids and
remingtonocetids are found in coastal and tidal deposits with freshwater
influence. Early protocetids are associated with shallow nearshore
environments. Not until the later fully marine-adapted protocetids are
fossils found in clearly open marine deposits. These are also the first
whales that would have been capable of worldwide dispersal, and they are
indeed the first to be found outside Indo-Pakistan!
The whales evolved after the extinction of the large marine reptiles. It
is a repeated feature of the fossil record, that the extinction of animals
occupying a particular ecological niche is followed by the radiation of
another existing group into that vacated niche. This is the same pattern
that is seen with the rapid radiation of placental mammal herbivores and
carnivores following the extinction of the non-avian dinosaurs.
Transitional aquatic/terrestrial environments provide settings for the
evolution of features that are "preadapted for" either terrestrial or
aquatic existence. The first limbs are now understood to have evolved as
an adaptation for scrambling around in shallow water rather than as
terrestrial adaptations. The first tetrapods had internal gills and were
aquatic animals. However, once limbs appeared they provided a clear
adaptation that enable their bearers to exploit a previously empty niche.
> The flipper transition is only one of a whole host of others that had to be
> coordinated to produce the whale from whatever its precursor was. You know
> what these changes were and the magnitude of the problem of coordinating
> them. But I don't believe you have addressed the problem. Do you really
> believe that these coordinated changes were brought about by random mutations
> (with respect to the future) selected by whatever environment, or genetic
> drift, or any other undirected process?
The whales are illustrative here. In addition to the reduction in limbs
serval other skeletal changes occurred. For terrestrial animals the pelvis
and shulder girdles must be firmly attached to the vertebral column in
order to support the body against gravity. In water, the body is buoyant.
In the fossil specimens the vertebral column is progressively detached from
the limbs. In the early protocetids the pelvis was connected to the
vertebral column by only a single vertebra. In later protocetids the
pelvis was completely separated from the vertebral column. Associated with
this is a progressive change in swimming from limb propulsion to tail
For a similar account of turtle evolution see:
Lee, M.S.Y., 1996, Correlated progression and the origin of turtles:
Nature, vol. 379, p. 812-815.
I find these changes to provide no particular unique challenge to
Undirected in what sense? From within nature -that is, from a creaturely
perspective - evolution is undirected. From a broader retrospective view -
evolution does have direction. From a theological perspective - God is
accomplishing His creative will in perfect accord with His goal to
establish the Kingdom on Earth.
> I have read before that you believe God is involved even in random events,
> such as random mutations. I agree with that. But does that mean that (1)
> God actually directs random events, i.e., chooses and brings about which ones
> he/she wants to have effected, or (2) that God merely knows what the outcome
> will be? If (1) then you have _directed_ evolution, and that's a far cry fro
> m what the mainstream evolutionary biological community believes, if my
> understanding of it is correct.
God is continually active in Creation. If God were to withdraw His hand
the universe would cease to exist. Thus, I do not believe that God ever
intervenes in Creation because He never leaves it! How God works in and
through the Creation to accomplish His creative will I do not know. A
complete evolutionary explanation for the history of life changes God's
continuing, personal, intentional creative action not a wit. Just as
knowing how I developed from an unfertilized ovum changes my conviction
that I am an individual creation of God not a wit.
Buchholtz, E.A., 1998, Implications of vertebral morphology for locomoter
evolution in early cetacea. IN, J.G.M. Thewissen (ed.), The Emergence of
Whales, Plenum Press, New York, p. 325-351.
Williams, E.M., 1998, Synopsis of the earliest cetaceans: Pakicetidae,
Ambulocetidae, Remingtonocetidae, and Protocetidae. IN, J.G.M. Thewissen
(ed.), The Emergence of Whales, Plenum Press, New York, p. 1-28.
Thewissen, J.G.M., 1998, Cetacean origins: Evolutionary turmoil during the
invasion of the oceans. IN, J.G.M. Thewissen (ed.), The Emergence of
Whales, Plenum Press, New York, p. 451-464.
Thewissen, J.G.M., Hussain, S.T., and Arif, M., 1994, Fossil evidence for
the origin of aquatic locomotion in archaeocete whales: Science, vol. 263,
Gingerich, P.D., Raza, S.M., Arif, M., Anwar, M., and Zhou, X., 1993,
Partial skeletons of Indocetus ramani (Mammalia, Cetacea) from the lower
middle Eocene Domanda Shale in the Sulaiman Range of Punjab (Pakistan):
Contributions from the Museum of Paleontology, University of Michigan, vol.
28, p. 393-416.
Gingerich, P.D., Raza, S.M., Arif, M., Anwar, M., and Zhou, X., 1994, New
whale from the Eocene of Pakistan and the origin of cetacean swimming:
Nature, vol. 368, p. 844-847.
Keith B. Miller
Department of Geology
Kansas State University
Manhattan, KS 66506
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