Dinosaur Eggs for Kids
Every dinosaur started life inside an egg. Some were round, some were long, some were soft, and some are still a total mystery.
Did all dinosaurs lay eggs?
Yes. As far as scientists know, every dinosaur hatched from an egg, just like birds, crocodiles and turtles do today. Fossil eggs have been found all over the world, some in huge nesting grounds with thousands of eggs in one place.
Some fossil eggs even have tiny baby dinosaurs curled up inside. These are called embryos, and they help scientists work out which dinosaur laid which egg.
📏 How big were dinosaur eggs?
Here is a giant sauropod egg next to eggs you might know.
- Ostrich eggabout 15 cm long
- Sauropod eggabout 13 cm long
- Chicken eggabout 6 cm long
Sauropods like Brachiosaurus were among the biggest animals ever, but their eggs were about the size of an ostrich egg!
Why were giant dinosaurs’ eggs so small?
An egg can only get so big. A bigger egg needs a thicker shell to hold it together, but a shell that is too thick stops air getting in to the baby, and makes it too hard for the baby to break out.
So instead of laying a few enormous eggs, giants like Brachiosaurus’s relatives laid lots of small ones. At one famous site in Argentina, sauropods laid clutches of about 15 to 40 round eggs in bowl-shaped nests dug into the ground.
The museum’s egg detectives
What do we know about the eggs of the five animals in the Dinosaur Wing?
T. rex
Big, long eggs. No whole one has been found yet. The size comes from fossil babies.
Read more →Triceratops
A complete mystery! Nobody has ever found a Triceratops egg.
Read more →Velociraptor
Probably long eggs, kept warm in a nest like a bird’s. Its cousins laid blue-green eggs.
Read more →Brachiosaurus
Round eggs no bigger than a football, laid by the dozen in a dug nest.
Read more →Pteranodon
Soft, leathery eggs, buried in the ground like a turtle’s.
Read more →
The mystery of the missing Triceratops egg
More Triceratops fossils have been dug up than almost any other big dinosaur of its time, but not a single egg. Why? In 2020, scientists found that Protoceratops, a small, distant cousin of Triceratops, laid soft-shelled eggs, a bit like a turtle’s.
Soft shells rot away quickly instead of turning into fossils. So Triceratops eggs may have been soft too, which would explain why none have been found. Science is full of open questions like this one, and that is what makes it exciting.
Egg-cellent Dinosaur Facts
Some dinosaurs sat on their nests like birds.
Fossils of a dinosaur called Citipati show it sitting on its eggs with its arms spread over them, just like a bird keeping its eggs warm.
Some dinosaur eggs were coloured.
Chemical traces in fossil eggshells show that some of Velociraptor’s relatives laid blue-green eggs, a bit like a robin’s.
One duck-billed dinosaur is named “good mother lizard”.
Maiasaura nesting grounds in Montana hold nests, eggshells and babies, which suggest the parents looked after their young.
One site in Argentina has thousands of sauropod eggs.
Some of those eggs still contain embryos, with fossil skin you can see under a microscope.
Pterosaur eggs were bendy.
Pterosaurs like Pteranodon laid soft, leathery eggs. Hundreds have been found together in China.
Science words to know
- Embryo
- A baby animal still growing inside its egg.
- Clutch
- A group of eggs laid together in one nest.
- Eggshell
- The outer case of an egg. Hard shells fossilise far better than soft ones.
- Brooding
- Sitting on eggs to keep them warm and safe.
Quick quiz!
0 / 31. Why do scientists think no Triceratops egg has been found?
2. About how big was a giant sauropod’s egg?
3. What was the “egg thief” Oviraptor really doing on that nest?
Questions kids ask
Did dinosaurs lay eggs?
Yes. As far as we know, every dinosaur hatched from an egg, just like birds do today.
How big was the biggest dinosaur egg?
The longest ones found so far, laid by giant relatives of Oviraptor, could be up to about half a metre long. But even the giant sauropods laid eggs only about 13 centimetres long.
Has anyone found a T. rex egg?
No complete T. rex egg has been found yet. Scientists estimate its size from tiny tyrannosaur baby bones.
Did dinosaurs look after their babies?
Some did. Nesting sites of Maiasaura and fossils of Citipati sitting on eggs suggest some dinosaurs cared for their eggs and young.
The Dinosaur Wing
A fossil egg is hiding in the T. rex’s forest. Find it, check the Eggs page, and carry it to the nest where it belongs.
✔ The whole Dinosaur Wing is free to play
No ads, ever · Plays offline · Made for young kids and adults
