Triassic, Jurassic and Cretaceous: when did dinosaurs live?
Dinosaurs did not all live at once. The Mesozoic Era is divided into three periods that followed one another: the Triassic, the Jurassic and the Cretaceous. Stegosaurus lived in the Jurassic. T. rex came much later, near the end of the Cretaceous.
Three periods in order
The Triassic began about 250 million years ago, the Jurassic about 200 million years ago and the Cretaceous about 143 million years ago. All these dates are rounded.
The Cretaceous ended about 66 million years ago, in the mass extinction linked to the asteroid impact.
Triassic: the first dinosaurs
The earliest dinosaurs appeared in the Triassic. Back then, much of the land was joined together in one supercontinent, Pangaea.
Well-known animals such as Brachiosaurus, Stegosaurus and T. rex did not exist yet. The dinosaur story was only just getting started.
Jurassic: long necks and back plates
Brachiosaurus, Diplodocus and Stegosaurus are well-known Jurassic dinosaurs. Archaeopteryx lived in this period too.
Their fossils show very different bodies: long necks, spiked tails for defence, feathers and wings. T. rex was not part of their world.
Cretaceous: a long and changing world
The Cretaceous went on for so long that its animals did not all live together either. Spinosaurus lived earlier in the period than T. rex.
Tyrannosaurus and Triceratops lived near the end. Velociraptor was a Cretaceous dinosaur as well, while Pteranodon was a pterosaur.
Make your own timeline
Put Brachiosaurus and Stegosaurus under “Jurassic” and T. rex under “Cretaceous”. Then check the dates on their cards.
Write the date or the period on your drawings as well. That way you will not put animals together that never met.
Questions kids ask
- What is the difference between the three periods?
- They cover different stretches of time, and the environments and animals changed from one to the next. The order is Triassic, Jurassic, then Cretaceous.
- When was the Jurassic?
- Roughly 200 to 143 million years ago.
- Did T. rex live in the Jurassic?
- No. It lived near the end of the Cretaceous.
- Why does Jurassic Park mix dinosaurs from different times?
- Because it is a made-up story. It does not try to rebuild one real ancient world.
- Which of the three periods lasted longest?
- The Cretaceous. It lasted from about 143 to 66 million years ago.
- Did people live at the same time as T. rex?
- No. Humans appeared tens of millions of years later. We do live alongside birds, though, and birds are dinosaurs.
Remember this
- Remember the order: Triassic, Jurassic, Cretaceous.
- The title of a film does not tell you when every animal in it lived.
- When you compare dinosaur cards, check the dates as well as the names.