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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
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.
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
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