Karen Chin works at the University of Colorado's Museum of Natural History, where she is the curator of paleontology.
As a graduate student, Karen Chin worked with renowned paleontologist Jack Horner at a dinosaur excavation site in Montana. Her job is to cut thin slices from fossilized bones so that they can be analyzed under a microscope.
But it wasn't the bones that caught her attention.
I learned that someone had found fossilized feces, and I thought it was the strangest thing," she recalled. So she asked for the feces to be cut into thin slices. "When I look through the microscope, I can see plant cells that were ingested by dinosaurs 75 million years ago. It blew my mind away because I thought, 'Man, this is how you understand the interaction between dinosaurs and plants and other creatures.'" ’”
China is now one of the world's leading experts on dinosaur droppings, scientifically known as "dung fossils", derived from the Greek word meaning "dung stone" or "poop stone". She was even the subject of a recent children's book called "Clues in the Feces".
Recently, we visited her at the University of Colorado, where she is a professor of geological sciences and curator of paleontology, and we wanted to see what personal contact with fossil droppings could teach us about dinosaurs.
Walking into Chen's office, the first thing you notice is petrified feces everywhere. They come in shallow boxes that cover every surface and are stuffed with shelves, cabinets, and drawers.
They look like black rocks," she explained. "They don't have the shape of a sausage you'd expect to see in fossil droppings. They're a bit angular. ”
This is because, well, they fell a long distance from the dinosaur's butt to the ground, so it's likely to break on impact.
As for the size of dinosaur droppings, Chin said none of them were as tall as Jeff Goldbloom seen in Jurassic Park. The largest one she checked was 6 liters, a little smaller than a basketball.
"When I watched the film, I thought it was quite humorous," she said. "But it actually makes sense, because if you have a dinosaur in a zoo, they produce a lot of droppings. What is the zookeeper going to do with it, isn't it just piling it up in one place so that someone can transport it away later?”
Sometimes she can determine who fertilized it by nearby skeletal remains. But more often than not, the identity of ** remains a mystery.
As a paleoecologist, knowing exactly who made it may not be the most important thing," Chin said. "If you can tell who's being eaten and think about some of the common food webs in ancient environments, you can get a sense of what that environment was like. That's another reason why I love dungstones so much, because they're basically like receipts for carbon resources to be traded, flowing through the ecosystem. ”
Fossil fecal specimens found in the wild.
Over the years, Chin has made many discoveries that tell us about these ancient food webs and the eating behavior of dinosaurs – something we don't usually know from their bones.
First of all, it has always been believed that the dinosaurs evolved with mammals after the extinction of the dinosaurs, in fact, they lived around the Cretaceous period, and in order to feed the baby dinosaurs, they were happy to dig holes in the dinosaurs' meatloaf.
Another finding was that the Tyrannosaurus rex was not a delicate eater, as some scientists hypothesize, picking meat from the bones, but swallowing its prey along with the bones. This is the conclusion that China came to after they found bone fragments and undigested meat in their dung fossils.
The skull of a tyrannosaurus rex was about three feet long," she said. "They can't chew properly, so they grab and swallow. ”
One of her favorite discoveries was the discovery of large quantities of digested wood in the feces of herbivorous dinosaurs. This is confusing because today's herbivores can't digest wood because they can't break down a tough, gelatinous substance called lignin, which holds wood cells together. But Chin clearly saw decomposing wood in the feces of herbivorous dinosaurs and, oddly enough, crustacean shells.
So her thought was that maybe they weren't eating healthy trees at all, but rotting wood.
"White rot fungi can actually destroy lignin, and if they do, the digestibility of wood increases by 30 to 60 percent," she said. "So that means these dinosaurs have been feeding on rotting wood. It's really surprising. You just haven't heard of this behavior in modern animals. ”
At least, Chin said, scientists often replace dinosaurs' Xi eating habits with large mammals like elephants and rhinos. But then again, dinosaurs are not mammals. They are more like their modern descendants: birds. Some birds that feed on seeds start eating insects when they lay eggs for calcium to produce eggshells and protein to support the yolk.
Herbivorous dinosaurs would have eaten rotting wood and all the crustaceans, worms, and other creatures inside as they reproduced in order to obtain protein and calcium for their eggs.
So my hypothesis is that because we found these fossilized dung in the nesting sites of the dinosaurs, the dinosaurs had to change their diet when they reproduced," she explained. "Look, kid, if you're a 25-foot duck-billed dinosaur and you suddenly need to get a lot of protein, you're not going to chase animals like a T-Rex. But you can find a protein in rotting wood in the form of invertebrates, insects, crustaceans, worms – all things that will linger around rotten wood. ”
So the next time you think feces are just a bad smelling waste......Think again.
This tells us about the interactions between organisms, about cyclic processes," Chin said. "When you hold a fossil piece of feces, it really shows us the vitality of life – not just today, but in the past. ”