Why the Picture of Dinosaur Sex Bouncing Around the Internet Is Insane

On Thursday, a group of dinosaur experts from the University of Colorado, Denver, made a plausible case that they’d found evidence of theropod mating rituals. Based on the shapes of fossilized footprints and scrapes, the scientists write in the journal Scientific Reports, large meat-eaters like Acrocanthosaurus may have performed a courtship dance akin to the one seen among modern-day puffins. What seems less likely is the theory suggested by the art accompanying the press release: Theropods had raucous, rough, and roaring sex.

Paleontologist Twitter, which is a great place to lurk if you have an interest in dinosaurs, noticed something a little familiar with the image of large predators caught in the act:

The tyrannosaurs painted in flagrante on the left, as University of Southampton vertebrate paleontologist Darren Naish pointed out, come from a museum exhibit in Spain.

The boning bones at Jurassic Museum of Asturias aren’t actually fossils, but replicas; the posture displayed here is, charitably, a guesstimate. There are several factual hurdles: It’s hard to tell male and female tyrannosaurs apart, and we don’t really have a reference for bipedal animals that get so big. Based on living crocodiles and birds, there is good evidence that T. Rex had a penis, as science writer Brian Switek told Slate in 2015. Extrapolating from a duck’s corkscrew penis, paleontologist John Long estimates a Tyrannosaurus penis could have stretched past the two meter mark.

There’s much less evidence for dino sounds. And because we don’t have any Cretaceous-era MP3s, we have a hard time knowing exactly what noises they make. Though the Jurassic Park roar is impressive, it’s also mostly mammal cries, leaning heavily on screams of a baby elephant.

To paint the animal kingdom with a sweeping brush, the act of sex itself tends to be a quiet affair. Primates like bonobos may produce “copulation calls”, but observations of ejaculating birds such as the buffalo weaver displayed nothing more than shivers and clenched feet. (This author once watched elephants copulate at the Berlin Zoo, and though the visuals are seared into his brain there wasn’t much in the way of accompanying sounds.)

If today’s wolves are vulnerable during sex, it doesn’t take much to imagine that the top predators of the Cretaceous would want to bone softly, too.