Re: Gizzard

["Norton, Patrick" <Patrick.Norton@state.me.us>]

>From one post:

>...are there any small gastroliths in this specimen (A. lithographica)   
that may
indicate the presence of a gizzard ? if so are they near the throat or in   
a more posterior location?<

And, from another post:

>There is no evidence of any gastroliths in any of the Archaeopteryx
specimens.  Alan Feduccia has noted that the enantiornithine furcula is
similiar to that of Opisthocomus, suggesting a large crop.<

I'm obviously missing something here, but can anyone name any bird that   
is known to use stones in its *crop* to process food? As I recall, bird   
crops are most commonly used to temporarily store food for later   
transport to the stomach or for regurgitation to feed offspring. Only in   
a relatively few taxa does the crop play any role in gastric digestion or   
food processing--although some much more than others.  The most extreme   
example of that may be the Hoatzin, which has a crop that essentially   
replaces the functions of the stomach and gizzard as the primary organ of   
digestion--but all without the use of stones (as far as I know.)

A few examples of modern birds that use stones *in their crops* would be   
useful in following these speculations about possible gastroliths in the   
crops of Archaeopteryx (or Seismosaurus, for that matter.)