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RATITE PHYLOGENETICS



I didn't read the paper yet so bear with me:

Were tinamous included in the analysis?

<<This would put the separation of ratites as a group somewhere in the 
mid Cretaceous, which is the time period that a lot of fantastic new 
avian and dinosaurian fossils are coming from.   Does anyone (Ron 
Orenstein?) know if there is fossil evidence to support this?    Ratites 
are commonly accepted by one and all to be closely related to 
neornithines; but just how closely are they related to enantiornithines? 
Do they posses any characters that would be found in a highly derived 
enantiornthine?>>

There is little fossil evidence to support the notion that ratites were 
roaming around in the mid Cretaceous.  Really, all of the birds from the 
mid Cretaceous were enantiornithines, which are not related to any 
living birds according to EVERY SINGLE analysis cladistic or otherwise.  
Enantiornithines are relatively low on the totem pole of avian 
phylogeny.  In contrast to ratites (which may not even be a monophyletic 
group, but rather a paraphyletic assemblage of neornithine birds with a 
paleognathus) enantiornithines have many features which may preclude a 
close relationship with ANY living bird:

1)  Squamosal not incorporated into braincase.
2)  Extensive contacts of the nasals.  
3)  Posteriorly grooved furcula.
4)  Lack of (ossified) uncinate process.  
5)  Presense of gastralia (_Sinornis_).  
6)  Proximal fusion of metatarsals.  

1 (according to some), 2, 4, and 5 are primitive features found in 
theropod dinosaurs.  Plus, there's the characters that ratites share 
with ornithurines and neognaths, which are too numeruous to list here.
Compare the skull of _Sthruthio_ to the skull of _Anas_ and then compare 
both to an enantiornithine with a nearly complete skull such as 
_Gobipteryx_.  Notice the ratite and the duck share features like the 
lack of nasal bone contact, enalrged braincase, lack of a postorbital 
bar, an ectethemoid, THIN (and rounded in x-section) jugal bars that 
incorporate the quadratojugal, a joint between the qudratojugal and 
quadrate, and a quadrate that is DISTINCTIVELY double-headed with a 
sharp orbital process.  Look inside the _Encyclopedia of Dinosaurs_ at 
Chiappe's Aves section if you can't find any ornithological text.  
Chiappe lists some GOOD characters that link Neornithes together:

1)  Quadrate with sharp orbital process.
2)  Small acetabulum.
3)  Pubis-ischium-ilium subparallel.
4)  Prominent patellar groove.  

These are good charcters, and there are tons more that link ratites and 
neognaths but exclude enantiornithines.   

Some workers have published pectoral girdle and feather evidence that 
suggests that some paleognaths are the sister-group to galliforms. 


ENANTIORNITHINES

It seems lately that the Enantiornithes has become a covinient 
"trash-can" for ancestors of certain avian groups (at least here on the 
dino-l).  There is little certain in science or paleo but it can be for 
certain that enantiornithines are not ancestral to ANY modern bird 
groups.

Matt Troutman

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