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Re: birds and avians again



In a message dated 8/31/01 1:54:24 PM EST, tmk@dinosauricon.com writes:

<< "Bird" is a vernacular English term and hence its usage is dictated by the 
English-speaking public at large. I think it's pretty clear that most types 
of dinosaur do not fall under the common usage of "bird". >>

This is merely a historical accident that I think should be rectified. We now 
know that dinosaurs are more closely related to modern birds than they are to 
any other group of living animals. So it makes a lot of sense to expand the 
definition of "bird" to include dinosaurs and any other archosaurs that fall 
into the stem-group "birds" that I described. As far as formal naming of 
these groups goes, one could stick with a node-based Aves (Latin root 
"birds") for the clade including and descended from the last common ancestor 
of Archaeopteryx and modern birds, a la Linnaeus, and then name the more 
inclusive stem-group birds Ornithes (Greek root "birds"). (But I don't like 
pinning a major group like Aves to a single genus such as Archaeopteryx: if 
we find a slightly pre-archaeopterygid fossil flying bird, why arbitrarily 
exclude it from Aves?) The other extant archosaur crown group would retain 
the familiar node-based name Crocodylia, and the more inclusive stem-group 
crocodiles (all archosaurs more closely related to Crocodylia than to 
Ornithes) would become Suchia.

The vernacular, paraphyletic term "dinosaurs" would then denote the non-avian 
ornithans. The more I examine this system, the better I like it.