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Re: *Secernosaurus*: Immigrant or Indigenous?



On Sun, Jun 29, 2008 at 4:31 PM, David Marjanovic
<david.marjanovic@gmx.at> wrote:

> ...falls under "inevitable", because there is almost no post-Cenomanian
> halfway terrestrial Late Cretaceous in Africa. One such site was recently
> discovered in Tanzania, but the AFAIK only described tetrapod from there is
> a nameless gondwanatherian mammal...

Naturally, but my point is that, in the absence of such evidence,
other hypotheses should probably also be considered.

For example, finding good basal-hadrosaurid material from South
America, or any material from Africa or even Antarctica/Australia,
would pretty much refute the northern-immigrant hypothesis. On the
other hand, finding late-surviving basal hadrosaurids from (late)
Campanian or Maastrichtian deposits in western North America would
basically refute the Gondwanan-radiation hypothesis. Finding evidence
of a pre-Campanian land connection between N. and S. America would
also tend to refute the Gondwana indigene hypothesis.

In any case, it only takes one halfway-decent fossil (and some proper
dating) to show which is correct.

I guess I'm just wondering if any of these can be narrowed down with
*current* evidence.