Bos acutifrons  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".