Quaternary International 192 (2008) 6–13 Comments on the Pinjor Mammalian Fauna of the Siwalik Group in relation to the post-Siwalik faunas of Peninsular India and Indo-Gangetic Plain A.C. Nanda Wadia Institute of Himalayan Geology, Dehra Dun 248 001, India Available online 29 June 2007 Abstract Pinjor Mammalian Fauna, ranging in age from 2.58 to 0.6 Ma, is the youngest fauna of the Siwalik Group. The process of its extinction and migration started at 1.79 Ma and after 0.6 Ma there is no record of this fauna from the foothills of Himalaya. The post- Siwalik faunas are known from Peninsular India and Indo-Gangetic Plain. From Peninsular India two faunal horizons roughly of Middle Pleistocene and Upper Pleistocene ages are known. However from Indo-Gangetic Plain, only an Upper Pleistocene fauna is known. Pinjor Mammalian Fauna is very rich and comprised of 98 species. This fauna was widespread and during its time span migrated to the intermontane basins of Kashmir and Kathmandu. Both Peninsular and Indo-Gangetic faunas are scanty as compared with the Pinjor Fauna. Twenty one Pinjor genera are present in post-Siwalik deposits and these include six Pinjor species. Remaining 15 Pinjor genera with different species survived in post-Siwalik horizons of India. Thus Pinjor Fauna, on species level, shows gradual extinction and not the massive migration. Evidence indicates that about 45,000 years back along the present course of River Yamuna, there was at least a depression if not the presence of river, which acted as route of migration for the remnant faunas. r 2007 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction The Siwalik Group forms the southern most foothill belt of the Himalayas. This freshwater succession, known for its richness in vertebrate fossils, ranges in age from 18.3 to 0.22 Ma (Johnson et al., 1985; Ranga Rao et al., 1988). Pilgrim (1913) divided this succession into three divisions and further into various subdivisions and these are now referred to as ‘Subgroup’ and ‘Formation’, respectively. The formations of the Siwalik Group are designated as Kamlial and Chinji (Lower Siwalik Subgroup), Nagri and Dhok Pathan (Middle Siwalik Subgroup), and Tatrot, Pinjor and Boulder Conglomerate (Upper Siwalik Sub- group). All these formations except the Boulder Conglom- erate are fossiliferous. Thus, the youngest Siwalik fauna occurs in the Pinjor Formation. The post-Siwalik faunas are recorded from Peninsular India and Indo-Gangetic Plain. Two faunal horizons, belonging roughly to Middle and Upper Pleistocene are known from Peninsular India. However from Indo-Gangetic Plain, an Upper Pleistocene fauna is recorded. These faunas of Peninsular India and Indo-Gangetic Plain are together called post-Siwalik faunas. The observations in this paper are based on mammalian fossils. 2. Pinjor (Upper Siwalik) fauna of Himalayan foothills On the basis of magnetostratigraphic studies in India and Pakistan, the base of the Pinjor Formation coincides with Gauss-Matuyama or Chron C2An/C2r boundary (Opdyke et al., 1979; Tandon et al., 1984; Hussain et al., 1992; Ranga Rao et al., 1988, 1995) and this boundary is dated at 2.58 Ma (Cande and Kent, 1995). The Pinjor Mammalian Fauna (referred as Pinjor Fauna in this paper) is recognized from Jammu and Chandigarh regions of India (Ranga Rao et al., 1988, 1995; Nanda, 1997, 2002), Nepal (West et al., 1988; Corvinus and Nanda, 1994; Corvinus and Rimal, 2001) and from the Irrawaddy Valley of Myanmar (Colbert, 1943). It is also known from several localities of Pakistan (Pilgrim, 1913; Opdyke et al., 1979; Hussain et al., 1992), but is best developed in Chandigarh where 57 species ARTICLE IN PRESS 1040-6182/$ - see front matter r 2007 Elsevier Ltd and INQUA. All rights reserved. doi:10.1016/j.quaint.2007.06.022 E-mail address: nandaac@rediffmail.com