Palaeontologists are constantly trying to find out more about dinosaurs and what their world was like. From their diets and behaviour to how they parented, understanding them is a tricky business, because the only things we have to provide any clues are fossils. Researchers have to look at the fossils they find very carefully to determine whether they’re looking at a new species, an adult or juvenile dinosaur, or a male or female dinosaur. But how easy is it to tell whether the bones you’re looking at belonged to a male or a female? 

Dinosaur fossils are rare

Understanding the sex of a dinosaur is especially challenging because there are only small numbers of fossils available for any given species. The only sure way to know that a dinosaur was female is to find her bones with fossilised eggs still inside the lower part of her body. Eggs in the stomach, of course, would be more likely to show what the dinosaur ate for lunch. 

Looking at bones

Some palaeontologists have tried to distinguish males from females by looking at their bones. When female birds prepare to lay eggs, they take some of the calcium from their skeletons and deposit it as a kind of tissue called medullary bone. This allows them to make an eggshell when they are ready to lay. The theory was that if this type of tissue could be found in fossils it would indicate a female dinosaur. 

The problem with this approach is that the dinosaur would have to be close to laying eggs when it died. Studies have also suggested that medullary tissue is formed when animals are exposed to environmental stress, which would mean this avenue of research is not particularly helpful. 

Feathered fossils

Just like modern birds, it’s possible that dinosaurs looked different depending on whether they were male or female. Perhaps male dinosaurs that had feathers were bright and vibrant like male birds of paradise, with the females being less colourful. Research shows that the first meat-eating dinosaurs that developed feathers grew them on their forearms and tails - places that are easy to move for visual displays. 

One very rare example of extinct birds from the Early Cretaceous period shows that there were differences between males and females back then. Confuciusornis fossils show that males had long tail feathers, while females had much shorter ones. Thousands of specimens of this animal have been discovered, giving researchers more data to study than they have for dinosaurs. 

Discover dinosaurs near you

If you’re fascinated by dinosaurs, don’t miss the family theatre show, Dinosaur World Live. Using stunning puppets to introduce you to a range of dinos - from Microraptor to T-Rex - it makes for a great activity when you’re looking for family things to do in the UK. The Olivier Award winning production is currently touring across the UK and is perfect for kids aged three and up. Search ‘best family shows in the UK’ and book tickets at your local theatre today.