Re: Paul's new DotA taxa

["Nicholas Gardner" <n_gardner637@hotmail.com>]

Mickey Mortimer wrote:

"Averostra- An apomorphy-based taxon defined as all theropods with a 
promaxillary fenestra, or that descended from such taxa (must include 
Dromaeosauridae).  This is placed identically to Padian et al.'s 
Neotheropoda, but the issue is complicated by Dilophosaurus.  Dilophosaurus 
has a promaxillary fenestra (Witmer, 1997; Rauhut, 2000) and an uncertain 
phylogenetic placement.  Rauhut found it to be closer to ceratosaurs and 
tetanurines than coelophysoids, while most others have found it to be a 
coelophysoid.  If the former is true, Averostra would be a useful clade 
between Avepoda and Neotheropoda.  If the latter is true, Averostra could be 
a junior synonym of Avepoda (if coelophysids lost the promaxillary fenestra) 
or a junior synonym of Neotheropoda (if Dilophosaurus developed it in 
parallel)."

Promaxillary fenestra?  Wait.  What makes a fenestra a promaxillary fenestra 
as opposed to a maxillary fenestra?

"Paul doesn't use Coelurosauria, Maniraptoriformes or Maniraptora, for 
reasons I haven't read yet."

Has Protoavia appeared yet?


"Avepectora- An apomorphy-based clade defined as all taxa in which the 
majority of the distal edge of the coracoids articulate with the anterior 
edge of the  broad sternum at an angle of 45-90 degrees from the midline, or 
that descended from such taxa (must include Dromaeosauridae).  This is 
equivalent to Maniraptoriformes in his cladogram, though I'm personally 
unsure as to whether ornithomimosaurs and alvarezsaurids show the derived 
pectoral condition.  If not, it could be a good name for the enigmosaur + 
paravian node.  Unless we use Dromavialae, Aviplumosa, Avipinna or 
Aviremigia.  The first was not officially defined though, and the last three 
were only suggested."

There's always the undefined Protoavia.

"Avebrevicauda- An apomorphy-based clade defined as all taxa with less than 
eleven free caudals, or that descended from such taxa (must include 
Neornithes).  Paul says this is different from Pygostylia because 
Chatterjee's (1997) original use of this term excluded Confuciusornis.  Of 
course, Chiappe (2001) recently "recreated" this name specifically for the 
clade Confuciusornis + Neornithes.  I'll have to see about Chatterjee's use, 
and how it affects the now standard use of the term sensu Chiappe.  
Avebrevicauda might have a chance as the Sapeornis + Neornithes clade, right 
below Pygostylia sensu Chiappe.  But though Sapeornis has a pygostyle, it is 
small and we only have two free caudal vertebrae.  So it may not have a 
proper avebrevicaudan tail."

I never could understand what was so useful about apomorphy-based clades.

Nick Gardner
n_gardner637@hotmail.com

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