RE: Cretaceous loons

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Ken Kinman wrote:

     >Is there any credible published information that loons (Gaviidae) 
>actually existed in the Cretaceous?  Neogaeornis may be a
>hesperornithiform.

I'm not sure what qualifies as "credible", but Luis Chiappe affirmed the
referral of _Neogaeornis_ to the Gaviiformes (loons or divers).  I think he
put forward quite a good case for considering _Neogaeornis_ a loon.

Chiappe, L. M. (1996). Early avian evolution in the Southern Hemisphere: 
the fossil record of birds in the Mesozoic of Gondwana.  _Proceedings of the
Gondwanan Dinosaur Symposium; Memoirs of the Queensland Museum_ 39: 533-556.


>Doesn't that just leave Polarornis?  Is there anything besides the 
>shape of the cnemial crest and skull (both subject to convergence) that
>are known to link Polarornis with loons?  

A great many features have been demontrated to be subject to convergence -
this does not necessarily invalidate them as potential synapomorphies.


Tim



------------------------------------------------------------ 

Timothy J. Williams 

USDA-ARS Researcher 
Agronomy Hall 
Iowa State University 
Ames IA 50014 

Phone: 515 294 9233 
Fax:   515 294 3163