Insular dwarfism, a form of phyletic dwarfism, is the process and condition of the reduction in size of large animals – typically mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s – when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf breeds, called dwarfing

Dwarfing

Dwarfing is a characteristic in plants and animals whereby one or more members of a breed or cultivar are significantly smaller than standard members of their species...

. This process has occurred many times throughout evolutionary history, with examples including dinosaur

Dinosaur

Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...

s, like Europasaurus

Europasaurus

Europasaurus is a basal macronarian sauropod, a form of quadrupedal herbivorous dinosaur. It lived during the Late Jurassic of northern Germany, and has been identified as an example of insular dwarfism resulting from the isolation of a sauropod population on an island within the Lower Saxony...

, and modern animals such as elephants and their relatives.