Megafauna

Definition

Large-bodied animals, typically defined by mass thresholds ranging from 10 kg to 1,000 kg depending on ecological context; most commonly applied to vertebrates exceeding approximately 45 kg. The term emphasizes functional and ecological consequences of large body size—slow life histories, reduced predation mortality in adults, pronounced ecosystem engineering, and disproportionate conservation impact—rather than phylogenetic affiliation. Thresholds are relative to regional faunas and research questions; 'megaherbivore' and 'megacarnivore' specify trophic role.

Etymology

Greek megas (large, great) + fauna (animals)

Example

In paleoentomology, Carboniferous giant dragonflies such as Meganeura (wingspans ~75 cm) represent arthropod megafauna comparable in functional role to modern vertebrate aerial predators, illustrating that flight enabled insects to achieve megafaunal size despite tracheal respiratory constraints.

Synonyms

• large-bodied fauna
• macrofauna (in some ecological contexts, though often distinct)

Related Terms

• macrofauna
• megaherbivore
• island gigantism
• ecosystem engineer
• body-size spectrum
• charismatic megafauna
• functional extinction

Usage Notes

Thresholds vary by discipline: paleontology often uses 40–100 kg; marine biology may apply lower thresholds due to buoyancy effects. In arthropod contexts, 'megafauna' is occasionally applied to exceptionally large species (giant weta, coconut crabs, extinct griffinflies) but more commonly reserved for vertebrate-dominated assemblages. Contrast with macrofauna (typically 0.5 mm–10 mm in soil ecology) and mesofauna. The term carries conservation valence—'charismatic megafauna' denotes flagship species whose protection benefits broader ecosystems.