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Re: Haplocheirus and Gregory S. Paul
I'm sorry, that was imprecise of me. I must not have meant BCF but, rather, Mr.
Paul's hypothesis that at least the most derived maniraptorans descended from
an ancestor with flight capabilities superior to those in Archaeopteryx. What
would we call this, the Secondarily Flightless Maniraptoran hypothesis?
As for Oviraptorosaurs and Therizinosaurs, the most primitive known members of
both groups have fewer, rather than more, features in common with birds than
their derived members, suggesting that their ancestors were not aerodynamic.
Now the same holds true for alvarezsaurs with the addition of Haplocheirus. The
recent paper by Balanoff et al. on Incisivosaurus demonstrates that the most
bird like features of derived Oviraptorosaurs are convergences, and Falcarius
has a primitive propubic pelvis, and both are are larger than Ornitholestes.
These are just a few characters but of course there are many others that make
it appear that theses clades descended from flightless and glideless ancestors
though, of course, there could have been reversals.
The evidence at this point - and we must all be grateful to have so many
fortuitous discoveries within our lifetimes - seems to me to be reinforcing one
conclusion. The most parsimonious conclusion is that the most primitive
maniraptorans that had volant or glissant ancestors were the paravians.
Of course further discoveries and/or anlayses could completely rearrange
things, but the phylogeny of paraves has remained stable for many years and
has been continually reinforced by new discoveries. The ancestral states at the
nodes below this seem to be getting less and less aerodynamic with each new
What does everyone think? I am eager to read any differing opinions.