Evolution of Grasses and Grassland Ecosystems

The evolution and subsequent ecological expansion of grasses (Poaceae) since the Late Cretaceous have resulted in the establishment of one of Earth's dominant biomes, the temperate and tropical grasslands, at the expense of forests. In the past decades, several new approaches have been applied to the fossil record of grasses to elucidate the patterns and processes of this ecosystem transformation. The data indicate that the development of grassland ecosystems on most continents was a multistage process involving the Paleogene appearance of (C 3 and C 4 ) open-habitat grasses, the mid-late Cenozoic spread of C 3 grass-dominated habitats, and, finally, the Late Neogene expansion of C 4 grasses at…