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Re: dino extinction
>You'll get no argument from me on that! The presence of a condylarth
>(_Tingamurra_) from the early Tertiary of Australia hints that the
>dominance of marsupials on this continent came about not through
>default (i.e. the absence of placentals), but because the marsupials
>were competitively superior to placentals.
I don't know that I can buy htis argument based on a single tooth. We can
say that placentals were in Australia in the Eocene and disappeared by the
Oligo-Miocene (excepting bats of course). Why this is so is more difficult
to determine. Competative superiority could be an appealing hypothesis but
it is just as likely to be contingency or other possible factors.
Dr Paul M.A. Willis
Consulting Vertebrate Palaeontologist
Quinkana Pty Ltd