Re: Gizzard

["Matthew Troutman" <m_troutman@hotmail.com>]

<<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.)>>

Not one bird that I know of uses stones in its crop to process food.  

The hoatzin (Opisthocomus hoazin) ulitilizes the use of bacteria to 
process food in its (huge!) crop.  There has been some talk of taking 
abstracts of its crop bacteria to cows in its region so the cows can 
process the unnatural and often poisonous ruffage.  

Anyway, while on the topic of the hoatzin, what does everybody think 
about its relations?  Is it cuculiform, galliform, musophagid, coliform, 
cariamid, or foratid?  I currently am stumped as to what it really is.  
I used to think it was related to musophagids, foratids, and cuculiforms 
but I am no longer convinced of an of the relationships that have been 
inferred to it.  

Matt Troutman

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