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Re: Island-dwelling dinosaurs (was Re: Gargantuavis neck vertebra)
Dr Ronald Orenstein <ron.orenstein@rogers.com> wrote:
> I was under the impression that the placentals-beat-marsupials argument had
> been pretty well rejected, with evidence that the reverse may
> have happened on Australia.
As far as Australia is concerned, this hinges on the identity of a
single molar, named _Tingamarra porterorum_, from the Eocene of
Australia. The tooth has been regarded as coming from a "condylarth",
and therefore a non-volant eutherian. If true, it indicates that
placentals were once established in Australia, but were beaten out by
marsupials. However, not everyone is convinced that _Tingamarra_ is a
placental. One suggestion is that the tooth comes from an
ameridelphian marsupial (also known from the Tingamarra fauna). As
you might appreciate, this is a somewhat hotly contested topic. ;-)
Cheers
Tim