⏳ The age of dinosaurs

Dinosaurs ruled the land for an astonishing amount of time, more than one hundred and fifty million years. That is so long that the famous T. rex actually lived closer in time to us than to the earliest dinosaurs. Humans have been around for only a tiny sliver of that vast history.

The long age of dinosaurs is split into three parts. In the first, dinosaurs first appeared and were mostly small. In the second, giant long-necks and many others grew huge. In the third and last, famous dinosaurs like T. rex and Triceratops lived, right up until the great extinction ended their reign.

Scientists work out a fossil's age mostly from the rock layers around it. Layers pile up over time, so deeper usually means older, like pages stacked in a book. They also measure special clocks hidden in certain rocks, natural materials that change at a steady, known rate, to pin down an age in millions of years.

When dinosaurs first appeared, all the land was joined in one giant supercontinent, so early dinosaurs could roam almost everywhere. Over millions of years the land slowly split apart and drifted into separate continents. Groups of dinosaurs were carried away from each other and evolved into different kinds in different places.