How did dinosaurs mate, have sex, and reproduce? Fossil evidence offers some clues

Dinosaurs left behind fossilized bones and footprints that offer vivid glimpses into their everyday survival. Paleontologists can infer their diets, estimate their sizes, and even figure out how quickly they grew.

But there is one perplexing detail that has baffled experts for well over a century: how did these massive creatures have sex, and what were their mating rituals?

Theories about dinosaur courtship and copulation spark curiosity among researchers and casual observers alike.

Some imagine towering, long-necked giants struggling to coordinate their bulk, while others focus on smaller species trying to avoid spiky tails or protective armor.

One person at the forefront of this conversation is Ms. Riley Black, an American paleontologist who has examined the hidden world of dinosaur intimacy in her published commentaries for the Smithsonian Magazine.

“For more than a century, paleontologists have wondered about how dinosaurs mated,” said Ms. Black in one of her discussions on the subject.

“Comparisons to living birds and crocodylians hint that individual dinosaurs usually had a phallus or a clitoris, although hard evidence of such structures has not yet been uncovered.”

Dinosaur courtship rituals

Fossils tell us only part of the story. Bones and teeth can reveal feeding behaviors, while footprints occasionally capture intriguing hints about group activity.

Yet, when it comes to mating, the direct evidence is frustratingly limited because reproductive organs rarely – if ever – turn into fossils. Despite this challenge, scientists have found ways to glean indirect insights.

In 2016, a team of paleontologists led by Martin Lockley from the University of Colorado Denver identified unusual scrape marks believed to be “mating grounds” where large, carnivorous dinosaurs may have performed courtship displays.

These scrape marks give researchers a window into pre-mating behavior, hinting that dinosaurs had specific routines to woo potential partners.

Think of this as a type of “prehistoric foreplay” as the Daily Mail so eloquently surmised when discussing these mating grounds.

Clues about dinosaur mating

Birds are living descendants of certain dinosaur lineages, and their closest evolutionary cousins are crocodilians. By examining these groups, scientists can make educated guesses about dinosaur anatomy.

While many modern bird groups do not possess a visible penis, ducks and ostriches (some of the more ancient forms) still do.

Male crocodilians have a single penis concealed in a cloaca, which is the all-purpose opening for excretion and reproduction.

Given these observations, most specialists propose that dinosaurs likely had similar structures tucked away, ready for brief yet essential moments of contact.

This notion supports earlier work by researchers who saw parallels with living alligators and large birds.

All dinosaurs mated the same way

Although no confirmed fossil of dinosaurs locked in an intimate embrace has ever turned up, parallels with modern reptiles suggest that their mating was typically a direct act that involved the male positioning himself behind the female.

“All dinosaurs used the same basic position to mate. Mounting from the rear, he put his forelimbs on her shoulders, lifting one hind limb across her back and twisting his tail under hers” said Dr. Beverly Halstead, a noted English paleontologist who took an interest in dinosaur reproduction decades ago.

Precarious and dangerous positioning

This statement may sound simple, but it prompts visions of a precarious balancing act for massive sauropods. For creatures that outweighed elephants many times over, the mechanics seem daunting.

Researchers note that supporting a partner’s weight during mating would not necessarily exceed the stress a dinosaur’s hind limbs experienced during ordinary walking or running.

Some breakthroughs come from discoveries that are not related to mating positions at all.

Early parenting evidence

Scientists examining Tyrannosaurus rex bones have found medullary tissue in the thighbone of a pregnant female. This special type of bone tissue is found to form in modern birds when they are about to lay eggs.

This discovery confirmed that dinosaurs shared more reproductive links with birds than previously appreciated.

It also hinted at the age when these creatures reached sexual maturity, often earlier than one might assume. There are always loose ends in any discussion of dinosaur biology.

Some dinosaurs needed water to mate

Questions remain about how spiny, heavily plated creatures like stegosaurs managed intimate moments without injury.

It is also unclear whether some massive species needed water for extra buoyancy to protect the female from a partner’s weight.

New technology and fresh fossil sites offer hope for clearer answers. Computer modeling allows paleontologists to simulate possible mating postures based on the range of motion in fossilized joints.

Synchrotron scanning and CT imaging allows them peer deeper into ancient bones for evidence of medullary layers and other reproductive signals.

Dinosaur mating and future discoveries

Although a frozen-in-time snapshot of dinosaur mating has yet to be uncovered, many in the field anticipate that more insights into the private lives of dinosaurs are just around the corner.

Even a single skeleton with distinct indicators of reproductive behavior could reshape our entire understanding of how these creatures ensured their survival in a hostile, ever-changing world.

The original article is published in the Smithsonian Magazine.

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