Nearctic realm represented by the Madrean Region. Although North America and South America are presently joined by the Isthmus of Panama, these continents were separated for about 180 million years, and evolved very different plant and animal lineages. When the ancient supercontinent of Pangaea split into two about 180 million years ago, North America remained joined to Eurasia as part of the supercontinent of Laurasia, while South America was part of the supercontinent of Gondwana. North America later split from Eurasia. North America has been joined by land bridges to both Asia and South America since then, which allowed an exchange of
Gondwana formation of Gondwana began with the East African Orogeny – the collision of India and Madagascar with East Africa – and was completed with the overlapping Brasiliano and Kuunga orogenies – the collision of South America with Africa and the addition of Australia and Antarctica, respectively. The continent of Gondwana was named by Austrian scientist Eduard Suess, after the Gondwana region of central India which is derived from Sanskrit for "forest of the Gonds". The name had been previously used in a geological context, first by H.B. Medlicott in 1872, from which the Gondwana sedimentary sequences (Permian-Triassic) are also described.