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RE: Why did only avians survive?



One interesting theory I've heard is that neorniths were prevalent in
the southern hemisphere (for whatever reason), and since the south
weathered the extinction slightly better than the northern, it was these
birds that came through.  
I do tend to think, though, that a lot of who-survived-what is based on
coincidence.  Species of type X just happened to be dwelling in niches
that weren't so badly effected during the extinction.

Dan

Dinosaurs: http://www.bowdoin.edu/~dbensen/Welcome.html
Weird Dinosaurs: http://www.bowdoin.edu/~dbensen/Spec/Index.html
Taiko: http://studorgs.bowdoin.edu/taiko/


-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu] On Behalf
Of Tim Donovan
Sent: Friday, October 01, 2004 2:00 AM
To: david.marjanovic@gmx.at; dinosaur@usc.edu
Subject: Re: Why did only avians survive?


--- David Marjanovic <david.marjanovic@gmx.at> wrote:

> 
> No. Current paradigma holds that we simply don't
> know because there are
> _far_ too few fossils. _Extremely_ few

 Poor choice of words.


> Enantiornithes from the Maastrichtian
> are known... very few birds are known from that time
> in general!
> 
> There exists an idea 

  Funny English. :)


>for why Neornithes survived
> while all the rest did not.
> It points out the different lifestyles of all those
> clades. The Neornithes
> of the time were generalists and/or depended on
> freshwater ecosystems;

  Didn't Stidham and Hope mention numerous neornithine
shorebirds?



> generalists fare generally better during mass
> extinctions (pardon the pun),
> and freshwater ecosystems were the least damaged of
> all because their food
> webs often don't start with living plants.

  But what about heat and ejecta?  IIRC at least one
study concluded they can't even survive acid rain.
 


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