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Re: Crop for seed-eating found in Hongshanornis and Sapeornis



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

>>  "[...] nearly 100 Sapeornis chaoyangensis specimens and [...] more
>>  than two dozen Hongshanornis longicresta specimens"
>
> What!?!
>
> Only 2 specimens of *S.* are published, or 4 if we're generous, and only 1
> of *H.* is? And yet there are such mind-boggling numbers!?!


Good thing too.  Because of the 100 or so _Sapeornis_  specimens,
apparently only two have the crop preserved; and of the more than two
dozen _Hongshanornis_, only one shows a crop.  The absence from most
specimens is undoubtedly an artifact, as mentioned by the authors,
However, this casts into doubt the contention of Zheng &c that the
absence of a crop in "intervening forms" (i.e., those forms more
crownward than _Sapeornis_, but more basal than _Hongshanornis_) is
real.


Further, _Sapeornis_ and _Hongshanornis_ are not as phylogenetically
remote from each other as the paper states.  _Sapeornis_ is a
non-ornithuromorph ornithuran (either a basal pygostylian, or the
sister taxon to Pygostylia), and _Hongshanornis_ is a basal
ornithuromorph.  Given the likely presence of a crop in _Jeholornis_,
which is even more basal, I still maintain that it was more
parsimonious for a crop to have evolved once, and to have been present
in the common ancestor of _Jeholornis_, _Sapeornis_ and
_Hongshanornis_.  A crop might even be plesiomorphic for Avialae (=
the most inclusive clade containing _Passer_ but not _Dromaeosaurus_
or _Troodon_).


> Yes, I know *Sinornithosaurus* and apparently *Microraptor* are in the same
> situation.


There's also over 100 _Jeholornis_ specimens too, as mentioned by Zheng &c.





Cheers

Tim