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Ji and Ji's Classification



(following up my post of Gauthier and de Queiroz's classification of birds
in the Ostrom Symposium volume)

The next (second) chapter is, "How can we define a feathered dinosaur as
a bird?" by Ji Qiang and Ji Shu-an.

More discussion of what _Aves_ should mean, but, oddly enough, it focuses
more on what "bird" should mean. As I've said in this forum and others
before, I don't think taxonomists should be trying to dictate the
definitions of purely vernacular terms.

They conclude that "bird" should be defined similarly to Gauthier and de
Queiroz's definition of _Avialae_ -- based on the possession of wings with
feathers (but no mention of powered flight). They don't seem to settle ona
definition for _Aves_, though. (It's kind of odd to me that two
Chinese researchers are writing about how to define an English word, but
missing the formal, international term ... oh well.)

It's an interesting discussion, though, even if I disagree with the
conclusion.

But what's really interesting is the cladogram presented:

Theropoda (stem)
|--Ceratosauria (stem)
|  `--Coelophysis
`--Tetanurae (stem)
   `--Avetheropoda (node)
      |--Carnosauria (stem)
      |  |--Allosauridae
      |  `--Sinraptoridae
      `--Coelurosauria (stem)
         `--Metatheropoda (node; new clade)
            |--Aptilonia (stem)
            |  `--Compsognathus
            |--Eoptilonia (stem)
            |  `--Sinosauropteryx
            `--Maniraptoriformes (node)
               |--Arctometatarsalia (stem)
               |  `--Troodon
               |--Oviraptorosauria (stem)
               |  `--Oviraptor
               `--Maniraptora (diagrammed strangely; probably meant to be stem)
                  |--Dromaeosauridae
                  `--Dromavialae (node; new clade)
                     |--Chuniaoia (stem)
                     |  `--Protarchaeopteryx
                     `--Avialae (node)
                        |--Archaeopteryx
                        `--Aerialae (node; new clade)
                           |--Enantiornithes (stem)
                           |  `--Sinornis
                           |--Orthornithes (stem)
                           |  `--Confuciusornis
                           `--Neornithes (stem)
                              |--Paleognathae (stem)
                              `--Neognathae (stem)
                                 `--Aves

I'm assuming stem- and node-based usages based on how they are diagrammed
-- some of the ones I list as node-based could be intended as
apomorphy-based, for all I know.

The names "Metatheropoda", "Aptilonia", "Eoptilonia", "Dromavialae",
"Chuniaoia", "Aerialae"  and "Orthornithes", which I have never seen
before, are not mentioned anywhere in the text, just in this diagram. I
think maybe "new clade" was left off some of them due to space limitations
in the diagram.

They all seem kind of useless to me. "Aptilonia", "Eoptilonia" and
"Chuniaoia" (any guesses as to the etymology on that one?) are monotypic
as far as I can see, and the assertion that _Compsognathus_ has no
feather-like integument (hence the name "Aptilonia") seems a bit premature.

The other new clades have either already been named ("Aerialae" =
_Pygostylia_, "Orthornithes" = Confuciusornithidae or
Confuciusornithiformes) or appear to be anchored on taxa of uncertain
position ("Metatheropoda" anchored on _Compsognathus_ and
_Sinosauropteryx_; "Dromavialae" anchored on _Protarchaeopteryx_), that
is, if those are indeed the intended definitions.

The usage of _Aves_ as a taxon *inside* _Neognathae_ must be an error, I'm
thinking. And the fact that dromaeosaurids are excluded from "Dromavialae"
seems odd -- etymologically, "Dromavialae" looks like it was meant as a
synonym of _Eumaniraptora_.

Apart from the new names and the (unintentionally?) odd usage of _Aves_,
it's pretty standard, tho'.

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T. MICHAEL KEESEY
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