Bos planifrons

''Bos acutifrons'' is the most ancient representative of the genus ''Bos'', cattle. Fossils of an individual of ''B. acutifrons'' were found in middle Pleistocene-aged strata of Siwalik Hills of Kashmir, in either modern Pakistan or India, in the 19th century. The prehistoric species was described, along with ''B. planifrons'', by Richard Lydekker in 1878. In 1898 Lydekker synonymised ''B. planifrons'' with ''B. acutifrons'', reconsidering the skull found to be that of a female individual of the same species.

Edwin H. Colbert in 1935 first suggested that from this species the modern species of ''Bos'' arose, with the aurochs, ''B. primigenius'', the ancestors of modern taurine cattle, evolving from the Indian Subcontinent via ''B. namadicus'', a smallish prehistoric species of cattle described by Hugh Falconer in 1837 from a fossil recovered in the early 19th century from Narbada (known at the time as Narmada by the British Raj) in central India. ''B. namadicus'' and ''B. primigenius'' are thought to have split 0.61 and 0.85 million years ago based on a study of the accumulation of differences in mitochondrial DNA by MacHugh ''et al''. in 1997, with Badam and Sankhyan in 2009 dating the existence of ''B. namadicus'' to the middle to late Pleistocene. Colbert's theory was expanded by Pilgrim in 1947 and followed by subsequent authors, until 2007 when Bienvenido Martínez-Navarro ''et al''. proposed an alternative theory that ''Bos'' in general and ''B. primigenius'' in particular arose in Africa. Following the 2009 discovery of the remains an African species of ''Bos'' in Eritrea, ''B. buiaensis'', which also immigrated into the Levant, this theory gained currency based on morphological and chronological grounds. Conversely, the presence of ''B. primigenius'' remains in the Levant which pre-date the earliest remains of both ''B. buiaensis'' and ''B. namadicus'', as presented by Ofer Bar-Yosef and Miriam Belmaker in 2011, cast doubt upon this 'out-of-Africa' theory as well as the theory that aurochs developed from ''B. namadicus''.

The species ''B. acutifrons'' first appeared in the early Pleistocene, some 2.58 million years ago at the earliest, and died out around 1 million years ago. Duvernois in 1990 proposed it evolved directly from an Indian species of '' Leptobos'', perhaps ''L. falconeri'', along with the Pleistocene genera or subgenera '' Bison'' and '' Bibos''. Martínez-Navarro ''et al''. consider that the ''Bos'' genus most likely arose in Africa descended from '' Pelorovis oldowayensis'', described by Hans Reck in 1928 from Olduvai Gorge, Tanzania, which was itself derived from the older species ''P. turkanensis'' described from northern Kenya. Both ''Pelorovis'' species were moved to genus ''Bos'' by Martínez-Navarro ''et al''. in 2014, which would make the oldest ''Bos'' species African.

Tong ''et al''. in 2018 also call the Martínez-Navarro hypothesis into question, pointing out that there are good morphological ground to separate the genus ''Pelorovis'' from ''Bos'', which would invalidate the theory.

References

{{Taxonbar, from=Q1083618

Bovines
Prehistoric bovids
Pleistocene mammals of Asia
Pleistocene even-toed ungulates
Fossil taxa described in 1898