We paleontologists have always loved bones, but that’s sometimes caused us to overlook another important resource: coprolites, the technical term for fossilized poop. I like to think I have an eye for ancient excrement, but it can be incredibly difficult to find. Sometimes, though, the poo finds you. This past year, I was in southwestern Wyoming searching for fossils in 50-million-year-old sediment. Snow, rain, and wind are constantly eroding the sandstone slopes. It gets extremely slippery. As I was coming down a steep hill, I started to fall and instinctively grasped what I thought was a sturdy rock. But the stone came out in my hand, and I tumbled right down. When I got up, I realized the stone was one of the largest coprolites I’d ever found. It had a consistent texture, no skeletal bits sticking out, and was the size of a hearty calzone, all of which suggests it came from a large herbivore. We found a few more coprolites in that area, so we think it was a watering hole or a nesting ground—and ideal for preserving poop. As told to Claire Maldarelli This article was originally published in the Summer 2019 Make It Last issue of Popular Science.
