Geoscience Reference
In-Depth Information
mere act of dinosaur-cloacal pinching would have affected the size of each exiting
nugget,meaningthetotalvolumeoffecesmighthavebeenquitehighbutcomposed
of many pieces snipped by a well-honed sphincter. Of course, falling and landing
on the ground would have altered the size and shape of such deposits depending on
mass, anal altitude, and relative solidity. Some feces would have gone “thud” and
flattened slightly on impact. Others would have gone “splat” and spread out over a
sizeable area. Those left by swimming dinosaurs might have been floaters, making
no sound at all. Smell would have entered this equation, too, as dung-loving insects
or other animals in the area would have picked up on any distinctive odors and hur-
ried to indulge.
Nonetheless, by far the most common question about dinosaur coprolites I've
heard is not “How do we know that this is dinosaur dung?” Instead, it is “How did
it fossilize?” This inquiry is understandable, considering how the closest encoun-
ters most urban dwellers have with dung either involves a brief experience in the
morning, picking up or stepping on dog doo, or cleaning a kitty-litter box. In con-
trast, people from rural communities, and especially those who live on farms, can-
not avoid feces, as livestock and all other animals leave “land mines” often and
everywhere.
First of all, preservation was really helped if these feces already had minerals
in them. This means carnivorous dinosaur scat had a better chance of preserving
than that coming from insectivores or herbivores because meat eaters were more
likely to ingest bone, and bone is composed of apatite. Second, anaerobic bacteria
in the feces could have assisted in preserving it, in which their metabolic processes
caused chemical reactions that made more minerals precipitate, and do so rapidly
(geologically speaking). In a few instances, this bacterially mediated precipitation
replaced undigested muscles and other soft tissues, leaving ghostly mimics of these
body parts in a dinosaur coprolite. And third, rapid burial, such as from a nearby
river flood, would have prevented fresh droppings from getting eaten, poked, prod-
ded, sniffed, trampled, washed away, or otherwise damaged. Under the right geo-
