How It Works

How do palaeontologists determine which period a dinosaur belonged to?

As dinosaurs and other fossils don’t come with a date stamped on them, geologists have to use evidence from the rocks in which they are found to ascertain which geological period they belong to. The absolute ages of rocks in millions of years can be estimated accurately using the decay of radioactive isotopes. However, relative ages (eg Triassic or Jurassic) are normally determined using particular fossils, such as ammonites, that lived only for short lengths of geological time. In the case of dinosaurs, tiny plant spores and pollen usually allow them to be placed into the correct geological period.

To learn more incredible facts, make sure you subscribe to How It Works magazine. Order it in printdownload it onto your digital device or subscribe today to ensure you never miss an issue!

Plus, take a look at:

Top 5 Facts: Dinosaurs

How did velociraptors kill? 

Interview with a dino expert

How did T-rex hunt its prey?