Box: Ages

The {Triassic} period was from 25 crore years ago to 20 crore years ago. This is when we had the early dinosaurs. Then we had the {Jurassic} period, from 20 crore years ago to 15 crore years ago, when the giant dinosaurs started appearing. Finally we had the {Cretacious} period, from 15 crore years ago to 6 crore years ago, when we had dinosaurs in all parts of the world. These three periods form the {Mesozoic} era, also known as the age of reptiles, from 25 crore to 6 crore years ago.

After that we have the {Cenozoic} era until today, known as the age of mammals. Although most of the dinosaurs died around 6 crore years ago, birds (which are modern dinosaurs) survived. In the Cenozoic era we had huge carnivorous flightless "terror birds" (1 to 3 metres tall) in the Americas, and Africa, until 20 lakh years ago. Three metre tall elephant birds (related to the New Zealand kiwi) seem to have been in Madagascar until thousands of years ago. Possibly humans were the ones who made them extinct. Some scholars think the {rukh} (roc) in the story of Sindbad from the book {1001 nights} may have been based on an elephant bird.