Curious about the world's oldest public bathroom? It's in Argentina and it's impressive, covering nearly 3,000 feet and dating back to a time when giant rhino-like creatures roamed the region, the BBC reports. Appropriately, the 240-million-year-old latrine is full of big fossilized feces, some up to 15 inches long and weighing several pounds. "There is no doubt who the culprit was," says Lucas Fiorelli, who discovered the massive toilet. "Only one species could produce such big lumps—and we found their bones littered everywhere at the site."
The culprit: the Dinodontosaurus, an early Triassic-period creature that was eight feet long and looked like a rhino. Their strategy: poo carefully, so that they defecated far from where they ate. "But it's also a warning to predators," said Fiorelli. "If you leave a huge pile, you are saying: 'Hey! We are a big herd. Watch out!" The researchers are also cracking open the feces and discovering fungi, extinct plants, and gut parasites. "Each poo is a snapshot of an ancient ecosystem—the vegetation and the food chain," said a co-author of the study.