We Know Dinosaurs Pooped, But Did They Pee Too?

Everybody poops. Including dinosaurs. In fact, researchers can tell a lot from dinosaur poops, even though they’re surprisingly hard to find. And now, scientists are pleased to report that some dino species also peed. 

Brian Switek at National Geographic explains that finding pee traces is pretty hard. It wasn’t until 2002 that researchers described a possible pee trace, Switek writes:

The first possible dinosaur pee trace to be discovered was described only recently. At a 2002 meeting of the Society of Vertebrate Paleontology, Katherine McCarville and Gale Bishop reported on a strange “bathtub-shaped depression” among dozens of dinosaur tracks just south of La Junta, Colorado. The scour, set in the 150 million year old stone of a long-lost lakeshore, measures approximately ten feet long, five feet wide, and ten inches deep. The shape is similar to splats McCarville and Bishop created by streaming water onto sand.

But the researchers didn’t publish anything about the pee, they simply presented about it at a meeting. In 2004, another group described a similar splatter pattern with ripples that suggested peeing. The question really comes down to whether or not dinosaurs had the right body parts to do the job.

To find out, researchers are turning to the descendants of dinosaurs: birds and crocodilians. Ostriches, for example, pee through their cloaca. “While no one has described a fossil of a non-avian dinosaur’s cloaca just yet, we can be confident that dinosaurs had such an arrangement,” Switek says.

All birds have a cloaca, but some combine solids and liquids into a single fecal stream. So when you get pooped on by a pigeon, for example, you’re getting both urine and feces. Dinosaurs could have done the same thing. But ostriches and crocodylians actually expel liquid first, and then feces - they pee and then poop. Dinosaurs could have also utilized this method. Nobody really knows yet. 

Rose Eveleth | | READ MORE

Rose Eveleth was a writer for Smart News and a producer/designer/ science writer/ animator based in Brooklyn. Her work has appeared in the New York Times, Scientific American, Story Collider, TED-Ed and OnEarth.