When Karen Chin, a paleontologist at the University of Colorado at Boulder, saw the massive piles of dinosaur dung in the 1993 blockbuster “Jurassic Park,” she began to laugh. It's a comical amount of waste. Near the midpoint of the film, the mathematician Ian Malcolm (Jeff Goldblum) walks up to a mound left by a sick Triceratops. He takes off his glasses — the poo rises to eye level — and remarks, “That is one big pile of s---.”

The camera pivots to paleobotanist Ellie Sattler (Laura Dern), elbow deep in another pile, looking for answers to the dinosaur's illness. No film before or since has treated dinosaur dung with the same care. 2015's “Jurassic World” left a bizarre dung-smearing scene on the cutting room floor. Friday's installment in the franchise, “Jurassic World: Fallen Kingdom,” doesn't have time to squeeze in a fecal examination between its volcanic explosions and dinosaur rampages.

Chin credits the original scene to her former boss, paleontologist Jack Horner, a consultant on the film.

“I think it was his idea to put dung in the movie,” she said. It was the early 1990s, and dino dung was on their minds: Horner and Chin had embarked on a detailed assessment of dinosaur feces found in Montana's Two Medicine Formation. They identified large mats of chopped up, digested plant matter as the waste from hadrosaurs.

There's a rich tradition of studying fossilized feces, which give an intimate look into dinosaurs' inner workings. “Fossil feces provides insights that we can't get from the bones themselves,” Chin said. “The most obvious is diet.”

Theologian and geologist William Buckland coined the term coprolite, meaning “dung-stone,” in 1829, predating the word “dinosaur” by a dozen years. Buckland recognized the blobby objects, which he said resembled “kidney-potatoes,” as feces.

Despite their long scientific history, coprolites are not easy specimens to understand. Bones clearly belonged to a specific owner. Tracing any given coprolite back to its producer is more of a challenge. Buckland initially believed his “kidney-potato” samples were produced by marine reptiles; the feces were later linked to Jurassic fish.

“The problem with coprolites is they’re rare and they don’t preserve well,” said Gregory M. Erickson, a paleobiologist at Florida State University. It's possible a Triceratops coprolite sits somewhere in a museum drawer or paleontologist's collection, but neither Chin nor Erickson know of a positive Triceratops I.D. 

Still, in some cases, scientists can trace the path from fossil poop to dinosaur. When Chin and Erickson were graduate students, they described, in the journal Nature in 1998, a massive tyrannosaur dropping. It was a foot-and-a-half long and six inches wide. “I believe it is the largest piece of carnivorous feces ever found on the planet,” Erickson said.

The high levels of phosphate in the coprolite indicated that a carnivore produced the waste. Plant-eaters don't excrete as much of the element. The most likely culprit, they concluded — the only predator big enough to leave it —  was Tyrannosaurus rex. Bits of bone studded the coprolite, some of the first evidence that T. rex jaws were strong enough to pulverize bone.

What's more, the animal had digested the bone bits to worn nubs. This indicated, Erickson said, “an extremely acidic stomach” with a pH of 1.5, near the most acidic end of human gastric juices.


A knobby crustacean shell embedded in fossilized dinosaur dung. (Karen Chin/Denver Museum of Nature & Science)

Chin has made a career of investigating coprolites — Erickson called her a “pioneer” in the field. In September, Chin and her colleagues announced a surprising find in the dung of herbivores: crustacean shells, revealing that these plant-eating animals also occasionally snacked on meat

But there are less obvious details that dinosaur dung can reveal than who ate whom. In dinosaur coprolites, Chin has found snails and dung beetle burrows. Poop, she said, was a critical habitat in these dino-dominated ecosystems.

And Chin's latest research uses coprolites like ancient thermometers. Marine organisms incorporate oxygen isotopes into their skeletons at different concentrations at different temperatures. Skeletons, consumed and excreted, are preserved in coprolites. In a study published in April, Chin and her co-authors looked for those chemicals in coprolites found in a chilly part of Canada, Devon Island.

Devon Island is so cold and remote that NASA has used it as a proxy for Mars. But 70 million to 90 million years ago, in a hotter world, its land temperatures reached as high as 60 degrees Fahrenheit, the isotope analysis revealed.

“I’ll admit I’m biased,” Chin said, “but I think we have been underutilizing coprolites in trying to understand ancient environments.”

As for that “Jurassic Park” scene, it shows too much poop for one dinosaur to deposit, even for a five-ton animal with digestive problems. Chin said she chalked up the piles, in her head, to shoveling zookeepers. Some dinosaurs in Two Medicine Formation left “latrine deposits,” Chin said, meaning a spot where several animals might go, but this behavior isn't well understood. Erickson, meanwhile, said he would expect more roughage; Triceratops guts weren't very efficient.

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