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Madagascar and neighboring islands form a distinctive sub-region of the Afrotropic ecozone, which botanist Armen Takhtajan called the Madagascan Region. The region is characterized by numerous endemic taxa of plants and animals, like the lemurs. Madagascar and the Seychelles are fragments of the ancient supercontinent of Gondwana. As Gondwana began to break up 160 MYA (million years ago), Madagascar broke away first from Africa, and 89 million years ago broke away from IndiaThe Republic of India is a large multicultural country in South Asia, with a population of over one billion. The Indian economy is the fourth largest in the world, in terms of purchasing power parity, and is the world's second-fastest growing economy.. Many of Madagascar's plant and animal species are of ancient Gondwanian origin. Madagascar remained close to Africa and for a time to India, and some plants and animals were able to cross the straits separating Madagascar from the neighboring continents. The other Indian OceanThe Indian Ocean is the third-largest body of water in the world, covering about 20% of the Earth's water surface. It is bounded on the north by southern Asia (the Indian Sub-continent); on the west by the Arabian Peninsula and Africa; on the east by the islands, like the ComorosThe Union of Comoros (until 2002 the Islamic Federal Republic of the Comoros is an independent country at the northern end of the Mozambique Channel in the Indian Ocean, between northern Madagascar and northern Mozambique. The country consists of three vo and Mascarene IslandsThe Mascarene Islands (or Mascarenhas Archipelago is the collective title of a group of islands in the Indian Ocean east of Madagascar, which include Mauritius, Reunion and Rodrigues. The collective title is derived from the Portuguese navigator Pedro Mas, are volcanic islands that formed more recently, and were populated by plants and animals from Madagascar, Africa, and the Seychelles.
Henri Perrier de la BâthieHenri Perrier de la Bathie ( 1873 1958) was a French botanist who specialized in the plants of Madagascar. He delineated the two chief floristic provinces of Madagascar see Ecoregions of Madagascar). Some of his works include La vegetation malgache (1921) (1921) proposed division of Madagascar into two distinct floristic provinceA floristic province is a geographic area with a relatively uniform composition of plant species. Adjacent floristic provinces do not usually have a sharp boundary, but rather a soft one, a transitional area in which many species from both regions overlaps. The Flore au vent (windward flora), later called the Région de l'Est (Eastern Region), includes those areas receiving the direct influence of the moist southeast trade windThe trade winds are a pattern of wind found in bands around Earth's equatorial region. The trade winds are the prevailing winds in the tropics, blowing from the high-pressure area in the horse latitudes towards the low-pressure area around the equator.s, which include the eastern coastal region and the central highlands, which run north-south along the spine of the island. The Eastern region also included humid pockets further westward, including Sambirano and Isalo . The Flore sous le vent (leeward flora), now called the Région de l'Ouest (Western Region), lies in the rain shadowA rain shadow (or more accurately, precipitation shadow is a dry region on the surface of the Earth that is leeward or behind a mountain with respect to the prevailing wind direction. A rain shadow area is dry because, as moist air masses rise to top a mo of the central highlands. It includes the drier western and southern portions of the Island, as well as the island's northern tip.The Eastern and Western regions can be further subdivided into seven terrestrial ecoregions. The Eastern region includes two tropical moist broadleaf forest ecoregions, the Madagascar lowland forests along the eastern coastal strip, and the Madagascar subhumid forests which occupies the highlands above 600-800 meters elevation. At the highest elevations, above 2000 meters, the subhumid forests transition to the Madagascar ericoid thickets , a montane grasslands and shrublands ecoregion.
The Madagascar dry deciduous forests , a tropical dry broadleaf forest ecoregion includes western Madagascar and northern tip of the island. Two xeric shrublands regions cover the southwest and south of the island; the dry forests transition to the Madagascar succulent woodlands in the southwest, and the drier Madagascar spiny thickets occupies the southernmost region of the island.
Eight flowering plant families are endemic to Madagascar: Asteropeiaceae , Didymelaceae , Didiereaceae , Kaliphoraceae , Melanophyllaceae , Physenaceae , Sarcolaenaceae, and Sphaerosepalaceae . One plant family, Mesdusagynaceae , is endemic to the Seychelles.
Before the arrival of humans, Madagascar was home to six lineages of mammals: lemurs, endemic carnivores, a pygmy hippopotamus, tenrecs , rodents, and bats. The lemurs are thought to be descended from a common ancestor, which crossed to Madagascar over 62 million years ago. Bones of extinct giant lemurs, as large as a gorilla, have been found on the island. Recent DNA evidence suggests that Madagascar's eight endemic carnivores, including the Malagasy "mongooses" ( Galidia , Galidictis , Mungotictus , and Salanoia ), fossa (Cryptoprocta ferox), Falanouc (Eupleres goudotii), and Malagasy Civet (Fossa fossana), are descended from a single ancestor which crossed from Africa to Madagascar 18-24 million years ago.
17 species of lemurs, including the giant lemur, together with giant tortoises, the pygmy hippopotamus, and the elephant bird, an enormous flightless bird related to the ostrich, became extinct after the arrival of the human settlers approximately 2000 years ago.