Archaeopterygid bird from China

[Curtis Clark]

on 2005-03-31 09:39 John Grehan wrote:
> It is restricted in that it is a smaller area than the total range of
> the group. If one said that the group originated over a range
> encompassing (but not necessarily restricted to) the current records I
> would be inclined to see that as something empirical.

Groups don't originate. Clades originate, when their stem species
originates, but, unless our empirical view of evolution in extant
organisms is seriously off-base, it all comes back to species. Your
point about the impossibility of ruling out that the range of the
original archaeopterygid encompassed all the locations of its
descendents is well-taken, but it is well-known from empirical evidence
of extant species that new species *can* originate in very localized
settings. I'm assuming you agree that at any given moment a species has
a "range", the cumulative area occupied by all its individuals. It seems
to me that both the "Darwinian" view that there *must* be a center of
origin and the panbiogeographic view that it is meaningless to talk of a
center of origin are equally worthless in addressing this aspect of the
biology of an extinct species.

--
Curtis Clark                  http://www.csupomona.edu/~jcclark/
Web Coordinator, Cal Poly Pomona                 +1 909 979 6371
Professor, Biological Sciences                   +1 909 869 4062