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

[Jason Brougham <jaseb@amnh.org>]

This may be my fault. I may have started this by saying that Incisivosaurus 
(the most basal known oviraptorosaur) is not very flighty. Then someone 
compared Incisivosaurus to Protarchaeopteryx. What I meant is that 
Incisivosaurus is big and relatively heavy. 

Incisvosaurus' skull is 11cm long, while Sapeornis' skull is 6 cm long (IVPP 
V13275 and IVPP 13276) and Protarchaeopteryx is 7 cm (NGMC 2125).

And, yes, that is interesting about Sapeornis moving down the phylogenetic tree 
in Turner et al. 2012.


________________________________________
From: owner-DINOSAUR@usc.edu [owner-DINOSAUR@usc.edu] on behalf of Tim Williams 
[tijawi@gmail.com]
Sent: Thursday, August 23, 2012 8:53 PM
To: dinosaur@usc.edu
Subject: 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.






Cheers

Tim