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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.

 

 At some point, I think I had heard that Australia has been a long-time host 
of...I want to say Rodents, but I'm not sure that's the right clade.

 

 Basically, I thought *Tingmarra* wasn't the only placental  (or if its not a 
placental, that there were still placentals on the landmass)

 

 

> 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. ;-)
>