(Qiu, Huang & Guo, 1987) (Equidae, Hipparionini) from the Late Pliocene
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TO L O N O G E I L C A A P I ' T A A T L E I I A Bollettino della Società Paleontologica Italiana, 57 (2), 2018, 125-132. Modena C N O A S S. P. I. The first occurrence of Plesiohipparion huangheense (Qiu, Huang & Guo, 1987) (Equidae, Hipparionini) from the late Pliocene of India Advait Mahesh Jukar, Boyang Sun & Raymond Louis Bernor A.M. Jukar, Department of Environmental Science and Policy, George Mason University, Fairfax VA 22030, USA; Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington D.C. 20013, USA; [email protected] B. Sun, Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, CHN; University of Chinese Academy of Sciences, Beijing 100039, CHN; College of Medicine, Department of Anatomy, Laboratory of Evolutionary Biology, Howard University, Washington D.C. 20059, USA; [email protected] R.L. Bernor, College of Medicine, Department of Anatomy, Laboratory of Evolutionary Biology, Howard University, Washington D.C. 20059, USA; [email protected] KEY WORDS - Asia, Cenozoic, Biogeography, Hipparionine horses, Dispersal. ABSTRACT - Hipparionine horses are well known from the Miocene of the Indian subcontinent and include several lineages. Their Pliocene record is poorly known in comparison. Here we report the first record of a hipparionine horse lineage,Plesiohipparion huangheense, from late Pliocene sediments in the Siwalik Hills in N.W. India. This species was formerly known from the late Pliocene of Northern China and the earliest Pleistocene of Turkey. This new occurrence presents us with two dispersal hypotheses for this species. By analyzing faunal connections across Eurasia, we conclude that P. huangheense most likely dispersed from China to India and Turkey from north of the Tibetan Plateau. RIASSUNTO - [Prima segnalazione di Plesiohipparion huangheense (Qiu, Huang & Guo, 1987) (Equidae, Hipparionini) dal Pliocene superiore dell’India] - I cavalli ipparionini sono ben conosciuti nel Miocene del Subcontinente Indiano, dove sono presenti con diverse line evolutive. Per contro, il loro registro fossile pliocenico è poco conosciuto. Questa nota riporta la prima segnalazione di un equide ipparionino, Plesiohipparion huangheense, da sedimenti del Pliocene superiore delle Siwalik Hills, nell’India nord-occidentale. Detta specie era nota in precedenza dal Pliocene superiore della Cina settentrionale e dal Pleistocene inferiore basale della Turchia. Questo nuovo ritrovamento suggerisce due possibili ipotesi di ricostruzione dello scenario di dispersione della specie. Alla luce di una discussione sulle connessioni faunistiche entro il continente eurasiatico, lo scenario più probabile per la dispersione di P. huangheense dalla Cina verso l’India e la Turchia è attraverso una via sita a nord dell’Altipiano Tibetano. INTRODUCTION in India generates new hypotheses for the dispersal of P. huangheense (Qiu, Huang & Guo, 1987) from China to Hipparionine horses have been known from the Indian Turkey, and increases our understanding of the diversity of Subcontinent since the early part of the 19th century large mammals in the Indian Subcontinent in the Pliocene. (Lydekker, 1882). A recent revision of late Miocene hipparionine horses recognized a diverse evolutionary series of species from the Potwar Plateau, Pakistan: GEOLOGY AND AGE Cormohipparion sp. Skinner & MacFadden, 1977, Sivalhippus nagriensis (Hussain, 1971), S. theobaldi Between 1834 and 1837, Captain Proby Cautley and (Lydekker, 1877), S. perimensis (Pilgrim, 1910), S. anwari Dr. Hugh Falconer, along with other military officers, Wolf, Bernor & Hussain, 2013, and Cremohipparion discovered several fossil deposits between the rivers antelopinum (Falconer & Cautley, 1849) (Wolf et al., Yamuna and Sutlej in Northwest India (Murchison, 1868). 2013). Pliocene hipparionines from South Asia have Their vast collection, including NHMUK PV OR 15790, been referred to “Hipparion” de Christol, 1832 s.l. on the was later shipped to and housed at the Natural History Potwar Plateau (Barry et al., 1982), and Hippotherium Museum in London. These early collectors did not keep antilopinum Falconer & Cautley, 1849, “Hipparion” detailed records of where the discoveries were made, theobaldi (Lydekker, 1877), “Hipparion” antelopinum therefore, giving us only an approximate estimate of the (Falconer & Cautley, 1849), and “Hipparion” sp. in the stratigraphic position and age of this specimen. However, Indian Siwaliks (Badam, 1979; Nanda, 1979; Moigne et historical records about the search area (Murchison, 1868) al., 2016). Here we report a Pliocene-aged mandibular offer clear insights into the age of the specimen. fragment of a hipparionine horse collected by P. Cautley The British explorers surveyed an area in the in the 1830s in India that does not belong to any known Himalayan foothills, between the rivers Yamuna in the genus from the Indian Subcontinent but represents east and Sutlej in the west, referred to as the Siwalik Plesiohipparion huangheense, a species known from Hills (Murchison, 1868). Modern palaeomagnetic studies Northern China and Turkey. The presence of the species have shown that fossiliferous sediments in this search ISSN 0375-7633 doi:10.4435/BSPI.2018.08 126 Bollettino della Società Paleontologica Italiana, 57 (2), 2018 Fig. 1 - Location map of the area surveyed by 19th century British explorers, between the rivers Sutlej and Yamuna, showing the extent of the different beds exposed. a) The region around the town of Chandigarh. b) The region around the modern Saketi Fossil Park near the Yamuna River. c-e) Different upper Pliocene exposures where hipparionine horse fossils have been found. area range in age from the late Pliocene (~3.6 Ma) to with greyish and reddish sandstones (Nanda, 1981; the early middle Pleistocene (~0.6 Ma) representing the Chapon Sao et al., 2016b). Upper Siwalik beds and consist of three lithostratigraphic units, the Boulder Conglomerate at the top laid down time-transgressively between 1.7 and 0.6 Ma, the Pinjor MATERIALS AND METHODS Formation (2.58-0.6 Ma) and Pre-Pinjor Beds (3.6-2.58 Ma) (Azzaroli & Napoleone, 1982; Ranga Rao et al., 1995; We compare the specimens of Plesiohipparion Kumaravel et al., 2005; Chapon Sao et al., 2016a). Middle huangheense described herein to our available database and Lower Siwalik exposures have not yielded many including a relevant group of late Miocene and Pliocene fossils (Nanda et al., 1991). Exposures of these sediments Old World hipparionine taxa (localities and ages discussed in the historical survey area are shown in Fig. 1a-b. in several previous studies: Bernor et al., 1988, 1993, In the Indian Subcontinent, hipparionine horses are 1996, 1997, 2003a,b, 2011). Tooth measurements and abundant in the late Miocene, rare in the Pliocene, and description follow the standard defined in Bernor et al. absent in the Pleistocene where they are replaced by (1997). Since the nomen Hipparion has been used in a Equus (Patnaik, 2013). In the area surveyed by the British variety of ways by different authors, we follow herein explorers, hipparionine specimens have been found in characterizations and definitions for hipparionine horses three geographic areas: 1) near the town of Masol; 2) near as provided in Bernor et al. (1996, 1997), and that the village of Khetpurali; and 3) near the town of Saketi “Hipparion” is a general taxonomic term for hipparionine (Fig. 1c-e). Sediments at Masol have been dated to ~2.9- horses not referable to the genus Hipparion sensu stricto 2.6 Ma (Chapon Sao et al., 2016a), while at Khetpurali, (s.s.) (Bernor et al., 2016). hipparionine horses have been found in deposits between In this study, we report three specimens, one from India 3.3 and 2.58 Ma (Nanda, 1981; Tandon et al., 1984), and that represents a novel occurrence of Plesiohipparion between 3.6 and 3.0 Ma near the town of Saketi (Azzaroli huangheense, and two comparative specimens, one & Napoleone, 1982; Mishra et al., 2013). Thus, it is most from Northern China, and the other from Turkey. The likely that NHMUK PV OR 15790 is late Pliocene in Indian specimen, NHMUK PV OR 15790, a mandibular age (3.6 Ma to 2.6 Ma), correlative with European MN fragment with p4-m1 (Fig. 2), is a part of the Falconer unit 16, and the Mazegouan horizons in the Yushe Basin, and Cautley collection of Siwalik vertebrates accessioned China (Opdyke et al., 2013). These Pliocene beds typically in the Earth Science collections at the Natural History consist of variegated and grey mudstones, interspersed Museum, London, UK (NHMUK). The Chinese specimen, A.M. Jukar et alii - Pliocene Plesiohipparion from India 127 THP10097, a complete mandible (Fig. 2), is accessioned Paleontology and Paleoanthropology, Chinese Academy in the research collections at the Tianjin Natural History of Sciences. Museum, Tianjin, China (THP), and the Turkish specimen, HU9102, is a mandibular fragment with p3-m3 (Fig. 2), Type locality - Dongyaocun, Pucheng County, Shaanxi accessioned in the research collections in the Laboratory Province, China. of Evolutionary Biology, Department of Anatomy, College of Medicine, Howard University, Washington D.C., USA Known distribution - Gaotege, Yushe, Shaanxi, and (HU). All measurements were taken using digital calipers Pucheng in Northern China, Gülyazi in Turkey and N.W. to the nearest 0.1 mm. India. Age range - Upper Pliocene to lower Pleistocene (3.9 SYSTEMATIC