[Taxacom] Dispersalist theory creating mysteries

[John Grehan]

A colleague of mine sent me the following quote from George Gaylord Simpson
(1953: 61-63).

"All the biogeographic features in the known history of mammals are best
accounted for on the theory that the continents have had their present
identities and positions...  the conclusion seems to apply not only to the
biogeography of mammals but also to that of all contemporaneous forms of
life."

I would assume that most if not all on this list do not adhere to the
continents having their present positions, but what one sees in molecular
dispersal approaches is the representation of modern biogeography mostly in
terms of the continents present geographic identities. Considering that
such an outlook is based on event calibrated divergence estimates that
represent minimal ages of origin, there would seem to be a lack of evidence
substantiating Simpson's claim (since minimal dates cannot falsifiy older
dates or events, no matter what one may personally believe is conceivable
about how much older a taxon may be). Would any on TAXACOM say otherwise?

John Grehan