15 million years ago

The evolution of grasslands or savanna

Evolution of the grasslands or savanna

Grasses are probably the most successful of all the flowering plants (angiosperms). They grow in many different environments, from salty marshes and sand dunes to freshwater lakes and rivers, to the dry steppes of Russia and the cold soils of the freezing tundra in the north of Canada to the hot savanna of Africa. In much of the world it is the grass that stabilises the soil and prevents it from being blown away by the wind.

Yet grasses are geologically very young angiosperms. They first evolved about seven months ago on the timeline (50 – 60 million years ago in real time), but less than two months ago in our timeline (only about 15 million years ago in real time) grasses quickly spread throughout the world.

What happened 15 million years ago that encouraged the spread of grasses? It all started when the world's climate began to cool. The tropical forests began to shrink and the grasslands (savanna) spread to take their place. Of course with the new grasslands, many new kinds of herbivorous animals began to thrive, including some of the primates that came down from the trees and started to live on the ground.

Grasses, sedges and rushes form the most important group of flowering plants for us. Not only do they provide us with food (corn, rice, wheat, barley, sugar cane, etc.), and our animals with fodder, but we also use them to build with (e.g. reeds, for thatching, and bamboo).

The Earth is now 46 years oldBack to 100-0 million years ago

The Earth is now 46 years old.