In terrestrial zoology, megafauna (Ancient Greek megas "large" + New Latin fauna "animal") are "giant", "very large" or "large" animals. The most common thresholds used are 44 kilograms (100 lb) or 100 kilograms (220 lb). This thus includes many species not popularly thought of as overly large, such as white-tailed deer and red kangaroo, and for the lower figure, even humans.
In practice the most common usage encountered in academic and popular writing describes land animals roughly larger than a human which are not (solely) domesticated. The term is especially associated with the Pleistocene megafauna — the giant and very large land animals considered archetypical of the last ice age such as mammoths. It is also commonly used for the largest extant wild land animals, especially elephants, giraffes, hippopotamuses, rhinoceroses, elk, condors, etc. Megafauna may be subcategorized by their trophic position into megaherbivores (e.g. elk), 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, and 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.