There was no doubt about it. Cycads and other warm-climate plants were not going to do well in the Cenozoic. On the other hand, flowering plants flourished. After the massive extinction at the end of the Mesozoic, wide open, barren expanses of land were all that was left of the thriving dinosaur age - until the grass came. It covered this impoverished landscape, spreading and preventing others from getting in the way. There were many reasons that grass became so successful. First of all, its roots protected the topsoil from blowing or being washed away by the forces of nature. It was able to take advantage of sunlight where trees and taller plants could not. Since grass was a flowering plant, its seeds were protected. And, the shorter roots could up the water before other plants could get to it. Obviously, grass must have had a tremendous effect on mammalian evolution. See why in Grass Part 2!

Cenozoic Era: Tertiary Period: Oligocene Epoch: Botanist's List