Many groups of living things from the past have disappeared.

You will never see a living dinosaur like T. rex. Dinosaurs died out about sixty-five million years ago. It's fun (and maybe scary) to think about those dinosaurs coming back to life, but they never will. Extinction is forever.

Click on all of these extinct animals to learn who they were and when they went extinct.

Ammonite by Sarah Rieboldt, © UCMP; Trilobite and Lambeosaurus skull © UCMP; Golden lion tamarin © Rare Species Conservatory Foundation, www.rarespecies.org; Quagga and passenger pigeon illustrations are in the public domain.