Re: [asa] Loading the ark (Ken Ham)

> I understand that a case can be made for evolutionary survival of stable
> species, such as the Wollemi pine or the coelacanth (although it seems a bit
> hard to imagine why, since many other animal and plant species in the same
> changing environmental conditions have died off long since).

One species can be successful when another one isn't, as long as the
first one isn't dependent on the second. Despite mammoths and
mastodons being extinct, lots of other species have survived to the
present.

> But if its remains were truly found in ancient geological layers (65 mya),
> but not in intervening geological layers, would this constitute some level
> of evidence against vast geological ages? I suppose two answers might be,
> if the plant virtually died off but not completely, then its small
> population wouldn't have created as much of a fossil trail, and just hasn't
> been discovered in newer layers; and, the evidence for the geological ages
> of the rocks is confirmed by many evidences, so just the absence of one
> particular species in one sequence of rock doesn't overturn other lines of
> evidence for the rock age.

Both of these are valid arguments. Also, a genuine example of
something totally disappearing and then reappearing would be a problem
for evolution but not for an old earth. However, given the
possibility of something being so rare for a while (or else simply not
in studied fossil deposits) and then turning up again, or of a later
species convergently evolving close similarity to the older form,
proving a genuine total extinction followed by re-creation of the
extinct form is nearly impossible.

I should clarify my telegraphic comments. The tree is now known as a
fossil from material within a few million years ago, because study of
the living trees has allowed us to see all the parts together. The
pollen is the same as a kind, previously of unknown source, that was
common in the fossil record up until geologically recently.

It's also worth remembering, as Keith pointed out, that the younger
and older versions are not absolutely identical. Organisms can change
in ways not immediately obvious, such as a change in lifespan in the
bivalve Arctica from a few decades in the Cretaceous to a few
centuries (over 400 years) in the modern species. The shells don't
look all that different.

-- 
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
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