Have you ever come face to face with a dragonfly the size of a hawk?

If you had walked on the surface of the Earth in the Carboniferous period, it could have happened. When people talk about gigantism, they tend to think of the famous dinosaurs that roamed the Earth during the Jurassic, 150 million years ago. However, dragonflies, millipedes, spiders and even scorpions once reached exceptional sizes. This amazing evolution is due to the constraints imposed by the living environment.

But how did insects so small reach such large dimensions? And why did they become extinct?