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Scientists have reconstructed a fossil to reveal how dinosaurs had sex

By Malavika Pradeep

Jan 24, 2021


We’ve all thought about it once in our life—either on our desks back in eighth grade or halfway through a Jurassic Park filmathon…or on the first chapter of Taken by the T-Rex.

‘How did they do it?’, ‘didn’t their tails get in the way?’, ‘what about all those spikes on their back?’, ‘won’t the female end up castrating the male with all these complications?’. There has always been a smothered buzz surrounding the question of how dinosaurs had sex due to the lack of scientific evidence. All things considered, they should have had a fair amount of sex given the fact that they thrived a whopping 165 million years on earth.

Since dinosaurs aren’t exactly in the position to ‘kiss and tell’, we expected paleontologists to fill us in. However, until now, they claimed to know very little about the topic since soft tissues rarely appear in fossils. We were once again left with Pornhub’s rendition of ‘dino sex’—until the 3D reconstruction of a Psittacosaurus happened.

Unearthed at a fossil site in northwestern China, the Psittacosaurus fossil is said to be a “rare gift” with its surprisingly intact orifice, skin and pigmentation. But paleontologists weren’t able to make much of it due to its flattening during fossilisation.

It was then that a team of scientists led by the University of Bristol undertook the three-dimensional reconstruction of the fossil. The study, published in the journal Current Biology, declares the presence of a ‘cloaca’ in dinosaurs. The cloaca is a multi-purpose opening on the body of many animals including crocodiles and birds. It is a cavity between their legs that allows them to pee, poop, have sex and lay eggs, all-in-one. This is probably why ScienceAlert describes it as the “Swiss Army knife of buttholes.”


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This finding also means that their sex organs were tucked inside the cloacal cavity. “You wouldn’t be able to see anything hanging low, or wobbling to and fro…,” writes Brian Switek in his book My Beloved Brontosaurus, putting an end to all careers in the dinosaur erotica industry. Both the male and female’s sex organs featured nothing but a slit under their tail from the outsideuntil turned on. “The slit is usually a vertical split, sometimes it’s a smiley face, sometimes it’s a sour face. This thing has a V-shaped structure with a pair of nice flaring lips…,” says Jakob Vinther, a paleontologist and senior lecturer at the University of Bristol’s School of Earth Sciences.

Most birds, termed “living dinosaurs” due to their descent, mate by rubbing their cloacas together for a few seconds. This brief ‘cloacal kiss’ is just enough time to transfer semen from the male to the female. Some paleontologists think dinosaurs may have mated like this. But Vinther believes this is not the case with the Psittacosaurus. He equates the cloacal flaps of the Psittacosaurus with that of a crocodile and suspects that they might have had a penis that emerged from the cloaca only while mating. The evidence to prove this, however, was not preserved in the fossil.


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The study further reports the presence of two small bulges in proximity to the cloaca which might have had musky scent glands. This, coupled with the fact that the cloaca was found highly pigmented with melanin suggests courtship among dinosaurs. The presence of such sexual beacons to attract mates are seen in baboons and breeding salamanders. “Knowing that at least some dinosaurs were signalling to each other gives paleoartists exciting freedom to speculate on a whole variety of now plausible interactions during dinosaur courtship. It is a game changer,” the team comments after the breakthrough.

The original fossil of the Psittacosaurus currently sits in a display case at the Senckenberg Natural History Museum in Frankfurt, Germany. And until we dig up more dirt in hopes of finding them caught in the act itself, let’s wonder who called it ‘extinction’ and not ‘XXX-tinction.’