A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura. The oldest fossil proto-frog Triadobatrachus is known from the Early Triassic of Madagascar, but molecular clock dating suggests their split from other amphibians may extend further back to the Permian, 265 million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest.