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Re: Fossil Stomach Contents in Marine Environments
I'm forwarding Mike Everhart's reply to M.J.Murphy's original post. A
shameless plug (although I haven't seen the book yet). DV :
> Have been reading Everhart's extremely cool "Oceans of Kansas" book,
Thanks for the nice compliment on the book..
> I could not help but note the frequent references to "fish in a fish"
fossils, or more generally fossils with preserved stomach contents. Am
I correct in inferring that fossils like this are more common in a
marine environment? If so, why? Because meals are more likely to be
swallowed whole? Or not?
I really don't have any data to compare the occurrence of our marine
fossils with those from a terrestrial environment, so I cannot say that
they are more frequent or not.. There is certainly some 'bias' in my
(over?) reporting of the stomach contents because that is an area of
special interest to me. An increased possibility of being preserved on a
fairly quiet and nearly anoxic sea bottom versus the likelihood of being
scavenged on land probably has something to do with it.
Reported in the book but also worth mentioning here:
There are two large shark (/Cretoxyrhina/) specimens at the University
of Kansas with evidence associated prey; one with most of a big teleost
(/Xiphactinus/ /audax/) inside.. .and another with the definitely
indigestible gastroliths left over from feeding on the guts of a
probable elasmosaur.. Another shark specimen (/Squalicorax/) at the
University of Wisconsin-Madison has the remains of several species of
prey inside, including fish, turtle and mosasaur.
... /Xiphactinus /seemed to have a bad habit of eating large prey
(/Gillicus/, mostly)..... and dying well before the prey was digested..
X-fish were quite large (12-18 feet is a good range for what we see as
fossils). The most famous specimen, the "Fish-in-a-fish" at the
Sternberg Museum, is only 13 feet long, and swallowed a 6 foot long
Gillicus shortly before it died. I suspect the prey weighed 90-100 lbs,
was quite strong itself, and struggled a bit as it went inside the
larger fish. As I suggested in the book, and Dan's artwork showed well,
that's a big object to swallow, and I suspect something vital in the
X-fish was punctured in the process. Another, much larger (17 ft)
X-fish that I found in 1996 also had the remains of a /Gillicus/ inside,
digested just enough to become disarticulated... but the death of the
X-fish must have occurred less than 24 hours after eating.
These instances may simply indicate bad luck or poor judgment on the
part of the predator... A 13 foot long X-fish must have fed on hundreds
of smaller fish without ill-effects during it's lifetime just to get
At least two specimens of a medium sized predatory fish (/Cimolichthys/)
are known to have died with a large /Enchodus/ inside as a last meal,
and another "choked" on a large squid...
The big /Tylosaurus/ in the exhibit at the Smithsonian also died with
the remains of a large meal inside.. in that case a juvenile
plesiosaur.. however, the gut contents were too far along in the the
digestive process to tell if the plesiosaur had been swallowed whole or
not.. I suspect that it had since most mosasaurs, and/ Tylosaurus/, in
particular were not well equipped for 'slicing and dicing" their prey.
... but were very similar to a snake in their adaptations for swallowing
large prey. I have no idea what killed it. Same goes for a big
/Tylosaurus/ found in South Dakota that was "stuffed" with the remains
of a bird, a large fish and small mosasaur as it's last meal.
A large elasmosaur we helped collect from the Pierre Shale in 1992-93
had a lot of ground up fish bones mixed with gastroliths in it's
crop/gizzard when it died.... suggesting that it died reasonably soon
Bottom line is that these specimens are somewhat more interesting to me
because of their association with prey, compared to the majority of the
remains found in the Smoky Hill Chalk, and are reported more often. The
incidence of preserved stomach contents is actually pretty low compared
to the huge number of vertebrate specimens that have been collected
there since l868.
Mike Everhart < email@example.com >
Adjunct Curator of Paleontology
Sternberg Museum of Natural History
Fort Hays State University, Hays, KS