Let’s Talk About Sex. Dinosaur Sex.

Senior Creative Consultant & Team Lead for Science
Stories February 08, 2018 Featured Image

Valentine’s Day is right around the corner, and we know exactly what you were hoping to receive for this joyous Hallmark holiday: 1,000 words on the mating habits of dinosaurs.

After all, nothing says “I love you” quite like a frank, in-depth discussion about how a bunch of extinct reptiles got freaky.

In all seriousness, we’re here to talk about dinosaur sex and, trust me, it’s not as simple as two T. rex catching each other’s eyes across a crowded watering hole. So, dim the lights, pour yourself a glass of pinot, and put on your favorite Boyz II Men album. Let’s take a trip down dino love lane.

While it’s quite probable that there were gay dinosaurs (homosexual behavior has been documented in every major animal group), this particular sex adventure will focus on heterosexual dinosaurs. So, to get us started, we’re going to need a male dinosaur and a female dinosaur. Easy enough, right? Think again.

It wasn’t until very recently that we’ve been able to determine the sex of an extinct dinosaur based on its fossil remains. A few years ago, at North Carolina State University, a team of paleontologists led by Dr. Mary Schweitzer analyzed a T. rex femur and found evidence of blood vessels and a special type of soft tissue known as medullary bone.

Found in modern birds, medullary bone is only present in females that are either laying eggs or have just laid them. Finding medullary bone in a fossilized Tyrannosaurus femur is a great indication that this particular T. rex was either pregnant—or had just been pregnant—at the time of death.

So we’ve got a female. Now we need a male.

Unfortunately, it’s a much harder to determine the sex of male dinosaurs, as we’ve found no evidence in the fossil record of bacula. Bacula are penis bones, and, in fact, most mammals have them, including our close gorilla and chimpanzee cousins. (Make no bones about it; humans are decidedly sans baculum.)

Yours truly holding a raccoon baculum.

For the sake of this discussion, let’s assume we’ve got both a male and a female T. rex. Romance is obviously in the air, so it’s high-time we got these dino love birds together. And, I do mean love BIRDS. Because we can’t just go watch two Tyrannosaurs doing the deed, we have to use modern corollaries to glean clues about what it was like for extinct animals to bump uglies.

And guess what? We’ve got their close cousins literally just outside our windows. After all, birds are dinosaurs. Similar to how humans are a special type of primate, birds are a special type of dinosaur, the only ones that are still alive today. #birdsaredinosaurs

All birds have something called a cloaca. Think of a cloaca as “one hole to rule them all.” It’s one hole, out of which comes pee, poop, and the sexy time juices. Countless birds practice something called a “cloacal kiss”—they smoosh their cloacas together, and the male sprays his sperm into the female.

Some of the oldest lineages of birds (e.g. ducks and other waterfowl) actually have internal penises (housed within their cloacas) which only make an appearance during mating attempts.

So all birds have cloacas, but not all birds have penises.

That’s only marginally helpful when trying to figure out what extinct dinosaur netherbits looked like, so let’s look at a different group of reptiles closely related to dinosaurs: crocodilians.

Alligators and crocodiles all have cloacas, but male alligators and male crocodiles also have penises that are housed inside the cloaca. The biggest alligators, which can reach 15 feet long, only have about five-inch penises. So what does that tell us about a 40 foot T. rex?

If we take the measurements from our well-endowed duck friend and our not-so-well-endowed alligator friend and scale up, we’re looking at T. rex penis that could be anywhere between the size of a 20 oz soda bottle…and a Honda Accord. But you know what they say—it’s not the size of the boat, it’s the motion of the ischium being propelled forward by the curvature of the sacral vertebrae, AMIRITE?!

Suffice it to say, we don’t really know what dinosaur genitalia looked like. But their loins aren’t nearly the craziest part about reproduction.

Picture, for a moment, two “thunder lizard” Brontosaurus attempting to mate. Or the newly discovered Titanosaur on view at the American Museum of Natural History, which weighed almost as much as a Boeing 737. If you’re a female being mounted, you’d need to take on the weight of something that literally shook the earth when it walked.

And what about dinosaurs like Stegosaurus or Ankylosaurus? These guys were covered head-to-toe in armor, bony plates, and giant spikes. I don’t care how many dinosaur size condoms you’ve got, that’s never gonna be safe sex.

At the end of the day, dinosaur reproduction remains one of the greatest sexual enigmas in the entirety of the animal kingdom. So, this Valentine’s Day, take solace in the relative normality of your own sex life. And hey, if your partner comes at you with a weird or unusual bedroom request, maybe throw ‘em a bone. It’s what T. rex would’ve wanted.

Want more dinosaurs in your life? Dustin’s got you:

Twitter: @DustinGrowick
Instagram: @DinosaurWhisperer
YouTube: The Dinosaur Show


written with 💖 by Dustin Growick

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