Fri, 07 Nov 1997 05:58:04 -0600 you wrote,
>Lets try this in another fashion. Maybe there are limits not to the extent
>of change but to the rate of change. Maybe only so much change can occur in
>a short time. This would mean that creationists are mistaking a limit to
>change with the inability to change extremely rapidly.
Actually, many creationists collect articles on evidences of very rapid
genetic change. If all the biogeographic speciation (of Hawaiian
honeycreepers, fish in isolated lakes, prolific plant genera, etc.)
occurred since the Flood less than 5000 years ago, changes at the species
level would have to be able to occur extremely rapidly. An astounding
amount of genetic versitility, whether the limits are discernable or not.
>The data supporting this idea comes from paleontology. We don't have to go
>very far back into the past before we find NO living animals. Here are the
>species living in each of the past. Living forms were all different in the
>past. They changed.
>Recent 4631(including species which went extinct in historical times)
>The two living species found in the Miocene are the carnivore Callorhinus
>ursinus and the bat, Rhinolophus ferrum-equinum.
Thank you for this list. I see below that these are all mammals.
I assume that by "no living animals" you mean "no extant species".
This is exactly what would be expected if the Miocene to Recent fossil
record represents speciation since the Flood. With all that environmental
change, much "descent with modification", through "survival of the fittest"
in each area would be necessary. This is reality in our fallen ecology.
>So while we may bump into limits over a 1000 year period, it might not be
>there if given more time.
On the other hand, if the stress of that much change pushed the limits of
genetic versatility in each of the kinds, they might become progressively
less able to change any more, and there would be many extinctions.
>The number of extinct species found in the various epochs of the Tertiary are:
I find this fascinating. Thank you, again! What is the reference?
Look at the array of numbers there -- the most extinctions in the Miocene,
with fewer on each side (the Oligocene is low because it is "short" (a
thinner sequence) (Gk. oligo = little or few) and the Eocene is higher
because it is "long" (thicker sequences).
extreme diversity of the Eocene (which could be interpreted as massive
after the floodwaters receded) starts to tend toward the present
biogeography, with what I call "differential survival" (some plant kinds
dying out in one area but surviving in another, while others survive and
speciate in other areas...).
With the Pliocene cooling and drying there was the spread of grasslands
which profoundly affected the speciation of ungulates, etc., and after that
there was less (but still some) extinction of vertebrates.
>The average species is only found in one of these epochs. This implies that
>the fauna almost entirely turns over with the passing of each epoch. This
>is another difficulty for the global flood--explaining why different forms
>are deposited in the various layers, inspite of the fact that most
>represented in each epoch.
In the Tertiary, I expect a lot of "turnover", as I noted above. Ernst
Mayr's conditions for optimum speciation (small population size, low
predation, low competition, open niches, etc.) would be exactly fulfilled
in the immediate postflood environment.
As you know, paleontologically, species are defined largely by skeletal or
dental differences. Any difference is likely to be given species
designation, so even interbreeding varieties may be given different
form-species names (like our hypothetical chiuahua and great dane -- there
was an article on that, noting that domestic dog varieties might be
classified paleontologically into several genera!). The faunas have many
such related form-species and are not _completely_ different.
>On the genus level the numbers of members of extant mammalian genera in the
>various geological epochs is:
>Triassic there are 4 genera--none with living members
>Jurassic 43 genera-none with living members
>Cretaceous 36 genera-none with living members
>Paleocene 213 genera-none with living members
>Eocene 569 genera- 3 with living members
>Oligocene 494 genera 11 with living members
>Miocene 749 genera 57 with living members
>Pliocene 762 genera 133 with living members
>Pleistocene 830 genera 417 with living members
>Doesn't this mean that life has changed? I see only two possibilities.
>Evolution or progressive creation that mimics the pattern of evolution
Sure, life has changed. But there are more than those two possibilites.