In terrestrial zoology, megafauna (from Greek μέγας megas "large" and New Latin fauna "animal life") are large or giant animals. The most common thresholds used are weight over 40 kilograms (90 lb) or 44 kilograms (100 lb) (i.e., comparable or larger in mass than a human) or over a tonne, 1,000 kilograms (2,205 lb) (i.e., comparable or larger in mass than an ox). The first of these include many species not popularly thought of as overly large, such as white-tailed deer and red kangaroo. In practice, the most common usage encountered in academic and popular writing describes land mammals roughly larger than a human that are not (solely) domesticated. The term is especially associated with the Pleistocene megafauna – the land animals often larger than modern counterparts considered archetypical of the last ice age, such as mammoths, the majority of which in northern Eurasia, the Americas and Australia became extinct within the last forty thousand years. It is also commonly used for the largest extant wild land animals, especially elephants, giraffes, hippopotami, rhinoceroses, and large bovines. (Of these five categories of large herbivorous mammals, only bovines are presently found outside of Africa and southern Asia, but all the others were formerly more wide-ranging.) Megafaunal species may be subcategorized by their trophic position into megaherbivores (e.g., elephants), megacarnivores (e.g., lions), and, more rarely, megaomnivores (e.g., bears). Other common uses are for giant aquatic species, especially whales, any larger wild or domesticated land animals such as larger antelope and cattle, as well as numerous dinosaurs and other extinct giant reptilians. The term is also sometimes applied to animals (usually extinct) of great size relative to a more common or surviving type of the animal, for example the 1 m (3 ft) dragonflies of the Carboniferous period.
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