Archaeopterygid bird from Chinan

John Grehan jgrehan at SCIENCEBUFF.ORG
Fri Apr 1 10:05:50 CST 2005


Comments below in response to several postings. I think I'm at my
three-a-day limit so I will probably not post anything more until next
week.

> Behalf Of Ken Kinman
> Okay,
>       Just to please you, let's say Archaeopterygidae originated
somewhere
> in Eurasia (no fossils known elsewhere).  

That's fine with me - it fits the facts as we have them.

).  I would assign eastern Asia as having the
> highest probably of containing the center of origin, western Asia as
> having moderate probability; and Europe with lowest probability of the
> three... probability).  Is that empirical enough?

No - there is nothing empirical about this at all. It's a complete
fantasy that does not come from the fossil record. It's a theoretical
proposition that, as I keep saying, seems to be more an imagined reality
than a reality as such and so far the reasoning appears no different to
that offered by Darwin in the first place.

I am inclined to agree with Richard Pyle's comments about the geographic
distribution of rare(ish) fossils telling us more about the geographic
distribution of circumstances conducive to fossil creation and human
efforts than it does about historical distribution patterns of certain
lineages. In a conservative context fossils only tell us the minimal age
of fossilization of a group/clade and at a minimum the location of that
fossil representative. Croizat argued that with the wealth of living
taxa it is more appropriate to orient the meaning or significance of
fossils using the living records than the other way around. As for the
center of origin - it's something one can give 'common sense' reasoning
to, but as a science its more like mythology.

I am also inclined to agree with the comments by Robert Mesibov on
centers of origin and areas of endemism. As far as I cam concerned,
areas of endemism, however constructed, are artificial entities and
therefore not appropriate units of analysis (although as a reviewer I
would not - and have not - call for rejection of a paper using areas of
endemism approaches simply because I work within a different framework).

In reference to Barry Roth's comment about other techniques such as
phylogeography - when it comes to fully differentiated entities there is
still the question of whether the Darwinian center of origin exists in
the first place. If one believes so, then one can make up any number of
criteria such as location of the oldest fossil, location of the most
basal lineage, location of the most derived lineage etc., etc. Cain back
in 1944 or thereabouts listed a whole series of alternative and
contradictory criteria. The whole notion of center of origin may start
off as seeming to have relevance from personal experience of mobility,
but once it is transformed into some kind of 'science' the result is
more like a brand of mysticism that appeals more to one's level of
credulity than anything else.

John Grehan




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