Geoscience Reference
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regressed to photographing one another squatting above these 75-million-year-old
trace fossils and giggling at the resulting images in our digital camera viewscreens.
Suddenly, a moment of seriousness intruded when I picked up one coprol-
ite—probably to pose in another picture with it—and noticed a snail's beautifully
coiled shell embedded in its matrix. Puzzled, I turned the sample all around and
scanned the surface for more such fossils, automatically practicing a basic tenet of
science: testing whether or not the initial observations could be repeated. In this in-
stance they were, as I found at least three snails in this coprolite. Excited, I men-
tioned this to whoever was closest to me, who fortunately shared my interest in
seeing something new, too. With an independent observer who had been cued on
the same search image, we quickly found more coprolites containing fossil snails
sprinkled between the wood and burrows.
What explained this seemingly oddassociation with snails anddinosaur poop?
Myfirstthought,saidjokinglyinthefieldwithothers,wasthatthesnailswerehap-
pily grazing on fungi growing on a decaying log. But then a hadrosaur came along,
took a big bite of the wood, chewed, and swallowed it, snails and all.
This idea, however amusing, was wrong. We did not know it at the time, but
Karen Chin had already finished studying these snails and surmised how they got
into feces in the first place. First of all, none of these gastropods could have sur-
vived a trip down a dinosaur's alimentary canal. If any had been gulped down as
inadvertent escargot, their thin calcareous shells, once bathed in the low-pH stom-
achacidsofahadrosaurproventriculus,wouldhavedissolvedinstantly.Asaresult,
Chin concluded these mollusks, which were in 40% (6 of 15) coprolites she stud-
ied, were either eating feces or whatever might have been growing on the feces.
In her paper, published later in 2009, she identified at least seven species of snails,
four terrestrial and three aquatic. These ecologically distinct snails painted a com-
plicated post-pooping history for the coprolites before they were buried and fossil-
ized. Some no doubt had been dropped on dry land, where terrestrial snails happily
grazed on them. However, some of these land nuggets might have been covered
