The tropical forests of the Andes and Brazil’s Atlantic Rainforest biome are separated by almost 1,000 km of drier areas with open vegetation in the Chaco, Cerrado (Brazilian savanna), and Caatinga (Brazilian semiarid) biomes. Today, these tropical forests are not connected, but the fact that they share closely related species and lineages suggests that these biomes were connected in the past. For example, 23 rainforest bird species have been found in both the Andean and Atlantic tropical forests.