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Re: Gastric stones of dinosaurs were not for milling food !
Richard W. Travsky writes:
On Thu, 21 Dec 2006, Dora Smith wrote:
I missed just one detail.
If the stones were not for milling food, what were they for?
One article suggested it was for the mineral content, my thought is
ingestion was incidental ;)
There's one easy way to tell dietry from non-dietry ingestion of stones; if
the stones were vitrious (like quartz) then they almost certainly weren't
ingested for mineral content. If, on the other hand, the stones contained
significant amounts of carbonate (or any other disolvable minerals) then
there's a chance they were like internal salt licks. Of course, carbonate
minerals probably wouldn't last long enough to end up in the fossil record,
unless death was soon after ingestion.
Personally, I'd have thought that loose sediment would have been a better
source of minerals than stones (lots of modern species eat clay for example,
even humans). Perhaps the stones were collected unintentionally along with
sediments? If so, then they were unintentionally swallowed during the act of
intentionally aquiring minerals (therefore sort of semi-intentional). That
said, some of those stones would have been more than noticable on the way
down. It's hard to imagine a sauropod swallowing a fist-sized stone by
accident - unless they provided both mineral content AND a mechanical
digestive advantage. Crocs certainly use gastroliths for more than one
GIS / Archaeologist http://www.geocities.com/dannsdinosaurs
Melbourne, Australia http://heretichides.soffiles.com