name Bos taurus was introduced by Carl Linnaeus in 1758 for feral cattle in Poland. The scientific name Bos primigenius was proposed for the aurochs by Ludwig Heinrich Bojanus in 1827 who described the skeletal differences between the aurochs and domestic cattle. The name Bos namadicus was used by Hugh Falconer in 1859 for cattle fossils found in Nerbudda deposits. Bos primigenius mauritanicus was coined by Philippe Thomas in 1881 who described fossils found in deposits near Oued Seguen west of Constantine, Algeria. In 2003, the International Commission on Zoological Nomenclature placed Bos primigenius on the Official List of Specific Names in Zoology and thereby recognized the validity of this name for a wild species. Three aurochs subspecies are recognised: The Eurasian aurochs (B. p. primigenius) was part of the Pleistocene megafauna in Eurasia. The Indian aurochs (B. p. namadicus) lived on the Indian subcontinent. The North African aurochs (B. p. mauritanicus) lived north of the Sahara. Evolution Calibrations using fossils of 16 Bovidae species indicate that the Bovini tribe evolved about . The Bos and Bison genetic lineages are estimated to have genetically diverged from the Bovini about . The following cladogram shows the phylogenetic relationships of the aurochs based on analysis of nuclear and mitochondrial genomes in the Bovini tribe: The cold Pliocene climate caused an extension of open grassland, which supported the evolution of large grazers. Bos acutifrons is a possible ancestor of the aurochs, of which a fossil skull was excavated in the Sivalik Hills in India that dates to the Early Pleistocene about . Fossils of the Indian aurochs were excavated in alluvial deposits in South India dating to the Middle Pleistocene. It possibly migrated west into the Middle East during the Pleistocene. An aurochs skull excavated in Tunisia's Kef Governorate from early Middle Pleistocene strata dating about is the oldest known fossil specimen to date, indicating that the genus Bos might have evolved in Africa and migrated to Eurasia during the Middle Pleistocene. Middle Pleistocene aurochs fossils were also excavated in a Saharan erg in the Hoggar Mountains. The earliest aurochs fossils excavated in Europe date to the Holstein interglacial 230,000 years Before Present (BP). A mitochondrial DNA analysis showed that hybridisation between the aurochs and the steppe bison (Bison priscus) occurred about 120,000 years ago; the European bison (Bison bonasus) contains up to 10% aurochs ancestry. Late Pleistocene aurochs fossils were found in