WILLIAMS, Ariz. — One way to tell how a Tyrannosaurus rex digests food is to look at its poop.
Bone fragments in a patch of fossilized feces at a new museum in northern Arizona, aptly called the Poozeum, are among the smaller pieces of evidence that suggest T. rex wasn’t much of a chewer, but instead swallowed whole chunks of prey.
The specimen is one of more than 7,000 on display at the museum that opened in May in Williams, a town known for its Wild West shows along Route 66, nature attractions and a railroad to Grand Canyon National Park.
The Poozeum sign features a bright green T. rex cartoon character sitting on a toilet to draw attention from the buzzing neon lights and muffled 1950s music emanating from other businesses.
Inside, the walls are lined with display cases filled with coprolites — fossilized feces from animals that lived millions of years ago. They range from tiny termite droppings to a massive specimen weighing 20 pounds (9 kilograms).
Poozeum president and curator George Frandsen bought his first piece of fossilized feces at a store in Moab, Utah, when he was 18, he said. He already loved dinosaurs and fossils, but had never heard of fossilized poop. From there, his fascination grew.
“It was funny. It was gross,” he said. “But I learned very quickly that it could tell us so much about our prehistoric past and how important they are to the fossil record.”
Coprolites aren’t very common, but they can make up the majority of fossils found in certain places, and people have learned more about them in recent decades, says Anthony Fiorillo, director of the New Mexico Museum of Natural History and Science.
They can be tricky to identify and in some cases specimens that resembled coprolites – with their pinched ends and striations – were further examined and eventually reclassified as something else.
“There are a number of sedimentary processes that can cause an extrusion of soft mud into another layer,” he said. “Think about your toothpaste. If you squeeze it, there might be some streaks on that toothpaste.”
Fossil enthusiast Brandee Reynolds recently visited the museum with her husband after discovering it was a slight detour from their planned road trip.
“I especially like sharp teeth and things like that,” she said. “I didn’t really find much coprolite, but who doesn’t like coprolite?”
A highlight of Frandsen’s collection is a specimen that holds a Guinness World Record for the largest coprolite left by a carnivorous animal. Frandsen said it’s more than 2 feet (61 centimeters) long and more than 6 inches (15 centimeters) wide, and is likely from a T. rex, given where it was found in 2019 on a private ranch in South Dakota.
Frandsen also holds the record for the largest certified coprolite collection of 1,277 pieces, registered in 2015 at the South Florida Museum in Bradenton, Florida.
His collection now stands at about 8,000 pieces. He doesn’t have the space to display everything in the museum in Williams, so he’s putting some of it online.
Don’t worry about odor or bacteria, Frandsen said. Those evaporated millions of years ago, when the feces were covered in sediment and replaced by minerals, making them rock-hard.
According to Fiorillo, location, shape, size and other materials such as bones or plants can determine whether something is a coprolite, but not necessarily what creature deposited it.
“I think most of us would say, let’s put the brakes on that and be happy if we can define carnivore and herbivore and then look at possibly the food cycles within each of these broad groups,” says Fiorillo, a trained paleontologist and author of books on dinosaurs.
Ideally, Fiorillo said he hopes that fossils that are rare and can contribute to understanding the prehistoric world will find their way into the public sphere so researchers can use them to form hypotheses about life long ago.
Like Frandsen, Fiorillo said he was fascinated by fossils when he was young. He pointed to private quarries in Wyoming’s Fossil Basin where the public can hunt for fossil fish, plants and even coprolites. People can also visit a research quarry to learn more about paleontology at nearby Fossil Butte National Monument.
If a child goes home inspired after finding a fossil or seeing one in a museum, that’s great, Fiorillo said.
“Maybe they are the next generation,” he said.