The aurochs (Bos primigenius; /ˈɔːrɒks/ or /ˈaʊrɒks/; pl.: aurochs or aurochsen) is an extinct species of bovine, considered to be the wild ancestor of modern domestic cattle. With a shoulder height of up to 1.8 m (5 ft 11 in) in bulls and 1.55 m (5 ft 1 in) in cows, it was one of the largest herbivores in the Holocene; it had massive elongated and broad horns that reached 80 cm (31 in) in length.
The aurochs was part of the Pleistocene megafauna. It probably evolved in Asia and migrated west and north during warm interglacial periods. The oldest-known aurochs fossils date to the Middle Pleistocene. The species had an expansive range spanning from Western Europe and North Africa to the Indian subcontinent and East Asia. The distribution of the aurochs progressively contracted during the Holocene due to habitat loss and hunting, with the last known individual dying in the Jaktorów forest in Poland in 1627.