The world continued to get cooler and drier in the Pliocene. Tropical rain forests and deciduous forests shrank. Grasslands grew, and many herbivorous mammals became grazers instead of browsers. A new land bridge at Panama brought a Great American Interchange. Hominid evolution took a new turn as some apes started to live on the savannah instead of the forests (Australopithecines). Late in the Pliocene the Greenland ice cap grew and became permanent, and the ice sheet of Antarctica grew to cover most of Antarctica.