[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

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



Tim Williams wrote:

<[O]f 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[.]>

I have more of a caution to fear that of these specimens, only three show an 
association in the anterior thoracic region or cranial to the pectoral region, 
that the "crop" is itself an artifact. Of course, I've not read the paper, so 
cannot comment on the actual details. But it would be interesting to see what 
precisely permits a crop to be preserved, despite the prevalence among 
specimens (presumably) of seed remains. Environment and region of preservation 
do not, necessarily, seem to be factors.

Cheers,

  Jaime A. Headden
  The Bite Stuff (site v2)
  http://qilong.wordpress.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 
Backs)


----------------------------------------
> Date: Wed, 7 Sep 2011 18:19:35 +1000
> From: tijawi@gmail.com
> To: dinosaur@usc.edu
> Subject: 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