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Re: At long last! Turner, Makovicky & Norell on dromaeosaurids

David Marjanovic <david.marjanovic@gmx.at> wrote:

>> _Protarchaeopteryx_ might have  been some form of parachuter or
>> glider
> What, at that size? Isn't it way bigger than any known parachuter and at
> least the size of the very largest known gliders?

But would _Protarchaeopteryx_ have weighed any more than _Sapeornis_?
BTW, I'm not suggesting that _Protachaeopteryx_ was an accomplished
parachuter or glider.  I also very much doubt that it was arboreal.
But if there were long, symmetrical feathers along the forelimbs, it
might suggest some "passive" aerial ability.

Speaking of _Sapeornis_, Turner &c recover this taxon as more basal
than _Jeholornis_, _Jixiangornis_ and confuciusornithids.  This means
that the pygostyle of _Sapeornis_ evolved independently of that of
pygostylian birds (avialans), including confuciusornithids and
ornithothoraceans.  Yet, the shoulder anatomy of _Sapeornis_ is more
primitive than that of the long-tailed _Jeholornis_ and
_Jixiangornis_, and the foot appears far better adapted for perching.
The early evolution of avialans was a weird place to be.