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Re: Dinosaur Genera List corrections #153 (JOKE)
George Olshevsky wrote-
> In my own taxonomy, Aves extends to the base of Dinosauria and
> includes all theropods--something the rest of the world hasn't exactly
> embraced yet. Sometime around 1974 (was it really that long ago??)
> placed a whole lot of theropods closer to modern birds than Archaeopteryx
> was, and that still makes a lot of sense to me.
I'm all for secondarily flightless maniraptorans, but isn't Aves is defined
as the most recent common ancestor of Archaeopteryx and neornithines? I
think flight first evolving in eumaniraptorans or maniraptorans is probable,
but I still think Archaeopteryx is a eumaniraptoran (descedant of the MRCA
of Deinonychus and neornithines). I don't think we have found these first
fliers yet, but they will be more primitive than Archaeopteryx when we do.
Having tiny, arboreal basal coelurosaurs is possible, but extending it down
to carnosaurs, abelisaurs and coelophysoids seems like a stretch.
I have the Thulborn paper (1984). It's one of the first theropod papers
with a phylogenetic analysis and cladogram I know of. For those of you who
don't have it, Thulborn has a matrix of 29 characters and 15 taxa. His
cladogram has the topology of (Coelophysidae (Compsognathidae +
Dromaeosauridae (Allosauridae + Caenagnathoidea (Archaeopteryx
(Tyrannosauridae ((Troodontidae + Ornithomimidae) (Avimimus
(Enantiornithines (Ambiortus (Ichthyornis (Hesperornithiformes +
Neornithes))))))))))). Names have been modernized in some cases. Wow,
Bullatosauria in 1984, who'd have thought? Of course, a lot has been
discovered since 1984, so I was curious what the result would be if his
matrix were ran in PAUP and updated with new data. If I just run his matrix
as is (with partially developed = 1 and present = 2), there are 90 mpt's.
These trees are big polytomies under the Avimimus portion of his cladogram.
So, his data didn't actually support Archaeopteryx being basal to
tyrannosaurs, troodontids or ornithomimosaurs. I updated his matrix with
the newest findings and found 345 mpt's with a large polytomy under an
(Archaeopteryx (Enantiornithines + Ambiortus (Hesperornithiformes +
Ichthyornithiformes + Neornithes))) clade. Far from supporting a
comparatively basal position for Archaeopteryx, when updated, his matrix
actually finds that Archaeopteryx is closest to the ornithothoracines.
Interesting what turns up when older studies are re-examined.
> We ain't seen nuthin yet.
Here I wholeheartedly concur. :-)