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A supercontinent cycle is the break-up of one supercontinent and the development of another, which takes place on a global scale. [4] Supercontinent cycles are not the same as the Wilson cycle, which is the opening and closing of an individual oceanic basin. The Wilson cycle rarely synchronizes with the timing of a supercontinent cycle. [1]
The Cretaceous–Paleogene extinction event killed off all dinosaurs except birds, but plant evolution in Gondwana was hardly affected. [72] Gondwanatheria is an extinct group of non- therian mammals with a Gondwanan distribution (South America, Africa, Madagascar, India, Zealandia and Antarctica) during the Late Cretaceous and Palaeogene. [ 73 ]
Three-fourths [18] of Madagascar's 860 [15] orchid species are found here alone, as are six of the world's eight baobab species. [19] The island is home to around 170 palm species, three times as many as on all of mainland Africa; 165 of them are endemic. [18] Many native plant species are used as herbal remedies for a variety of afflictions.
Map of Pangaea with modern continental outlines. The supercontinent cycle is the quasi-periodic aggregation and dispersal of Earth's continental crust.There are varying opinions as to whether the amount of continental crust is increasing, decreasing, or staying about the same, but it is agreed that the Earth's crust is constantly being reconfigured.
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Continental assembly and uplift also meant increasingly arid land climates, favoring the evolution of amniote animals and seed plants, whose eggs and seeds were better adapted to dry climates. [40] The early drying trend was most pronounced in western Pangaea, which became a center of the evolution and geographical spread of amniotes.
Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million in total. Animals range in size from 8.5 millionths of a metre to 33.6 metres (110 ft) long and have complex interactions with each other and their environments, forming intricate food webs .
Five species of krill, small free-swimming crustaceans, are found in the Southern Ocean. [39] The Antarctic krill (Euphausia superba) is one of the most abundant animal species on earth, with a biomass of around 500 million tonnes. Each individual is 6 centimetres (2.4 in) long and weighs over 1 gram (0.035 oz). [40]