Folks,
In a recent post Steve J. talks about the fossil record in commenting on
an article in nature. Now the point that a gradualism model of
evolution should leave more transitional forms than are found in the
fossil record is valid. But also be aware that in a punctuated
equilibrium one would expect many less transitional forms because of
stasis.
But that is not why I am taking time from preparing for a lecture to
respond to Steve. Steve's post shows a lack of understanding of the
nature of fossilization. One has to remember that it is a process that
is very selective in lots of ways. I work in very widespread deposits
of coal in the Carboniferous. We have loads and loads of details on
the plants in this coal swamp because when they died the dead material
fell into an anaerobic muck on the bottom (it doesn't change the picture
much if you are YEC) but except for caprolites (fossil dung) we have
almost NO record of the animals that munched on the vegetation. But
then in an occasional shale like the Mazon Creek deposits you get a
different environment that preserves both plants and animals but MOST of
them do not. Just another illustration is that we know there were upland
(non swamp environments but they are rarely preserved (which makes sense
since they are thought to be more environments of erosion and not
deposition).
In light of that, Steve you said, "had to argue that the fossil record
was *very* incomplete in order to hide the myriads of transitional
forms that the `blind watchmaker' would leave in his wake:" If you had
stopped with more I might agree, but given the nature of fossilization
and the fact that the theory even in a non punctuated model predicts
transitional forms to be around for less time you would not expect
myriads.
The difference between now and Darwin's day is that we have found so
many more localities and those rare windows like the Mazon Creek in the
Carboniferous and Burgess Shale and plaeontologists do feel that there
are not big gaps. But given the nature of fossilization if you are
going to make an argument on lack of transitions you should do it on
something like angiosperm leaves or coal plants for which there is an
excellent record in good depositional environments. You might be
surprised at the argument you could make, but first do a bit of reading
and find out what the nature is of the fossil record for groups of
organisms that tend to preserve well in the fossil record.
Now if I don't get thinking about nematodes and annelids, my zoology
class will have a poor record.
James and Florence Mahaffy 712 722-0381 (Home)
227 S. Main St. 712 722-6279 (Office)
Sioux Center, IA 51250
This archive was generated by hypermail 2b29 : Fri Mar 24 2000 - 08:04:47 EST