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Re: New Cretaceous bird and other papers

On Mon, 18 Feb 2002 22:22:48  
 David Marjanovic wrote:

>> You are saying (I think) that neornithines
>> outcompeted enantiornithines in the Antarctic and (presumably) other parts
>> of Gondwana.
>Nope. I'm saying that for whatever reasons there were no enantiornithines in
>Antarctica, maybe they never got there, who knows. (All my evidence is AFAIK
>one site on Seymour Island.) In South America Enanti- and Neornithes appear
>to have partitioned niches peacefully -- we have *Enantiornis* and
>Avisauridae among the former and *Limenavis* and *Neogaeornis* close to
>respectively ?among the latter.

I'm not very familiar with the Seymour Island site (other than what I've read 
on list).  But, how reliable is the fossil record of the island?  Is there 
enough material present to actually conclude that enantiornithines certainly 
did not live in Antarctica?  Based on what I know of Cretaceous Antarctic 
fossil sites, the overall material is often incomplete (despite the fact that 
sometimes the specimens themselves are complete).  

And, while I know that biogeographic barriers do exist, even for flying 
animals, I don't see how any barrier would prevent an entire group of animals 
from reaching a landmass .  A species' migration being prevented by 
biogeographic barriers?  Certainly yes; it has been observed.  An entire group? 


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