Thanks to a new fossil discovery, we suddenly know a lot more about dinosaur sex - Salon

A team of scientists from the University of Bristol and the University of Massachusetts Amherst revealed that they had discovered and described in detail a dinosaur's cloaca — that is, a vent in the animal's posterior that would have been the dinosaur's equivalent of an anus, urethra and genitalia — based on a fossil that had distinctly preserved the skin patterns of a Psittacosaurus, a dog-sized dinosaur related to the Triceratops.

Jakob Vinther, a paleontologist at the University of Bristol, told Salon. "Most of these animals have penises, except for some of the dinosaurs' descendants.

Thanks to the scientists' study of this cloaca, however, we now know a lot more.

"Now we can actually say that this type of cloaca is not suited for cloacal kissing, that is a cloaca that is suitable for penetrative sex," Vinther told Salon.

Although he said that scientists cannot determine the sex of the dinosaur they found, they noted that "the shape of the cloaca is somewhat distinct.

They sort of join together in one direction and then they flare out towards the tail." By contrast, bird cloacas "kind of looks like a swollen zit that is ready to be popped," Vinther said, although another close relative of dinosaurs — the crocodile — also has a pair of lips around its cloaca.

"In crocodiles, when you have these swollen lips there is a pair of glands below that can release this sort of fatty substance that are full of pheromones and smell irresistible to other crocodiles," Vinther explained.

In addition, Vinther identified something "quite surprising and unique" in the dinosaur's cloaca — namely, the fact that it was very colorful, which suggested that they were used for visual signaling.

But if you take, for example, birds, there are just two species of living birds that we could find that have a colorful cloaca.".