Re: R: One for the bird brigade

["T. Mike Keesey" <tkeese1@gl.umbc.edu>]

> I just checked Mike Keesey's DINOSAURICON, and he has kindly provided
> the web-head a cladogram of Neornithes.  It seems to my
> new-to-cladistics eye that the closer clade is Palaeognathae,
> including the polyphyletic tinamous (say that ten times fast) and the
> assorted rogue's gallery of ratites.

Your new-to-cladistics eye is still being developed. My cladogram says
neither that Paleognathae is "more primitive" than Neognathae, nor that
tinamous are polyphyletic.

Order of taxa in a cladogram is completely arbitrary. I tend to put big
groups below smaller ones -- makes for more aesthetic cladograms. This is
the only reason why Paleognathae appears before Neognathae.
 
These two cladograms:

Neornithes
|--Paleognathae
+--Neognathae

Neornithes
|--Neognathae
+--Paleognathae

... say exactly the same thing. There is a clade called Neornithes. It is
divided into two subclades: Neognathae and Paleognathae (or, if you
prefer, Paleognathae and Neognathae). Neognathae and Paleognathae are
sister groups. Saying that one is "more primitive" is generally a
subjective call, and hence not reflected in the diagram.

> So.  Ostriches, Emus, the always-fun Cassowary, big flightless
> feathered types, are the closest living ancestors to Archaeopteryx? 
> Strange but ... true?

Nope. All living birds are equally closely related to _Archaeopteryx_. In
fact, since _Archaeopteryx_ shares no clade with any other avian, no known
bird, period, is more closely related to _Archaeopteryx_ than any other,
at least in terms of phylogeny.

--T. Mike Keesey                                   <tkeese1@gl.umbc.edu>
THE DINOSAURICON                http://www.gl.umbc.edu/~tkeese1/dinosaur