In fact, Paul already knows that coelophysis lived around 200 million years ago, while iguanodon lived around 150 million years ago.
To do that, we have to learn a little bit about radioactive decay.
Scientists are always spouting information about the ages of rocks and fossils. Well, they figure it out using two different methods: relative dating and numerical dating.
Let's find out more about these geological dating methods in order to understand how Paul the Paleontologist can be so sure about the age of his dinosaur fossils.
That means they don't really know how old their rocks actually are.
The key in relative dating is to find an ordered sequence.