Megafauna

In zoology, megafauna (from Greek μέγας megas "large" and Neo-Latin fauna "animal life") are large animals. The most common thresholds to be a megafauna are weighing over 46 kilograms (100 lb) (i.e., having a mass comparable to or larger than a human) or weighing over a tonne, 1,000 kilograms (2,205 lb) (i.e., having a mass comparable to or larger than an ox). The first of these include many species not popularly thought of as overly large, and being the only few large animals left in a given range/area, such as white-tailed deer, Thomson's gazelle, 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 that are considered archetypical of the last ice age, such as mammoths, the majority of which in northern Eurasia, Australia-New Guinea and the Americas became extinct within the last forty thousand years.

Among living animals, the term megafauna is most commonly used for the largest extant terrestrial mammals, which includes (but is not limited to) elephants, giraffes, hippopotamuses, rhinoceroses, and large bovines. Of these five categories of large herbivores, only bovines are presently found outside of Africa and southern Asia, but all the others were formerly more wide-ranging, with their ranges and populations continually shrinking and decreasing over time. Wild equines are another example of megafauna, but their current ranges are largely restricted to the Old World, specifically Africa and Asia. Megafaunal species may be categorized according to their dietary type: megaherbivores (e.g., elephants), megacarnivores (e.g., lions), and, more rarely, megaomnivores (e.g., bears). The megafauna is also categorized by the class of animals that it belongs to, which are mammals, birds, reptiles, amphibians, fish, and invertebrates.

Other common uses are for giant aquatic species, especially whales, as well as any of the larger wild or domesticated land animals such as larger antelope, deer, horse and cattle, as well as dinosaurs and other extinct giant reptiles.

The term megafauna is very rarely used to describe invertebrates, though it has occasionally been used for some species of invertebrates (which are on average much smaller than vertebrates) such as coconut crabs and Japanese spider crabs, as well as extinct invertebrates that were much larger than all similar invertebrate species alive today. One example are the meganisopterans, dragonfly-like insects from the Carboniferous period with wingspans reaching 1 m (3 ft).