Grasslands spread
Grasses stop being a minor plant and start forming a biome, though the great plains are still to come.
- When
- —
- Duration
- 11 million years
- Known to
- ± 2 million years
- Era
- Oligocene, Cenozoic
Cooling and drying continental interiors favour grasses, which grow from the base rather than the tip and so tolerate being grazed and burned in a way that most plants cannot. Through the Oligocene open grassy habitats expand across the northern continents, and the mammals track the change with longer legs and higher-crowned teeth. This is still C3 grass and still patchy woodland-savanna rather than true prairie; the great grassland expansion, powered by C4 photosynthesis, waits for the Miocene.