One of my favorite old-school ways to call someone crazy is saying they’re “nuttier than squirrel shit.” It’s crude, whimsical, and feels like it’s rooted in some kind of natural fact of life. Squirrel poop is likely filled with nuts. As The New York Times reported, however, their ancient ancestors were apparently gnawing on mammoths and saber-toothed cats, which really makes you wonder where things started going wrong on their evolutionary timeline.

The discovery comes from the Yukon, where Klondike gold rush miners first exposed massive Ice Age fossils of woolly mammoths, steppe bison, and saber-toothed cats, all of which were preserved in the permafrost. Tucked away in those frozen walls were prehistoric ground squirrel burrows, including the little places they loved to store their poop, which also happened to be perfectly preserved as little fecal pellets.

In a new study published in Nature Communications, researchers analyzed DNA from 13 squirrel coprolites (aka turds) dating as far back as 700,000 years. Since squirrel burrows themselves were frozen solid, sealed off from the world, their poops remained largely intact, still containing some genetic fragments of what they once were and what they once contained. The scientists were pretty sure they knew they were dealing with once it thawed and they were hit with the classic, familiar scent of poop.

Ancient Squirrels Ate the Same Stuff Modern Ones Do… Plus Mammoths and Wolves

They found traces of grass, insects, and small mammals. But they also found genetic traces of much, much larger animals, like woolly mammoths, huge ancient horses, bison, wolves, and even sabertooth tigers.

These prehistoric squirrels may have been more carnivorous than their modern counterparts, but they weren’t out hunting megafauna. They were likely scavengers picking apart carcasses or chewing bones for nutrients. Typical rodent behaviors we still see today.

Poop can tell you a lot. If you find an animal bone, it tells you that animal existed. Finding an animal’s poop will tell you about the plant life of the area and the kind of insects that flew around; it can tell you who was eating what, and it can tell you the finer details of an ecosystem that hasn’t existed for millions of years. Poop is funny; it’s silly, it’s immature and gross. But it can also act as a window into the deep past, assuming you can stand the smell.