Bubalus platyceros (Bovidae: Mammalia) in the Sardhok Pabbi Hills of Pakistan

Muhammad Khaled Siddiq1, Muhammad Adeeb Babar1,2*, Muhammad Akbar Khan1, Muhammad Umar Ijaz3, Sayyed Ghyour Abbas1, Muhammad Asim1, Asif Mahmood Qureshi4, Mahboob Iqbal4 and Muhammad Akhtar4 1Dr. Abu Bakr Fossil Display and Research Centre, Department of Zoology, University of the Punjab, Quid-e-Azam Campus, Lahore 54590, Pakistan 2Department of Zoology, University of Okara, Okara, Pakistan 3 Department of Zoology , Wildlife and Fisheries, University of Agriculture, Faisalabad 4Zoology Department, Minhaj University Lahore, Pakistan Article Information Received 26 January 2020 Revised 11 May 2020 Accepted 27 June 2020 Available online 13 November 2020


INTRODUCTION
T he genus Bubalus originated in Asia and its fossil record is confined to the Pleistocene sediments of Eurasia (Lydekker, 1878;Pilgrim, 1939;Koenigswald, 1986;Akhtar, 1992). Most of the fossil relatives of Bubalus are found in the Siwalik Group. The African material from Setif (Algeria), Modder River, Free State Province (South Africa), and Naivasha (Kenya), assigned to Bubalus was synonymised with Syncerus by Gentry (2010). However, he synonymized Buffelus palaeindicus to Bubalus from Tunis. Extant Bubalina are found in Asia where five species of Bubalus live (Hassanin and Ropiquet, 2004). Today, Bu. bubalis (the water buffalo), a domestic species, is found in many parts of the world whereas Bu. arnee (the wild water buffalo) is native to the Indian subcontinent and Southeast Asia (Akhtar, 1992;Lever, 1985). Bubalus mindorensis (the tamaraw) is native to Philippine whereas Bu. depressicornis (the high mountain anoa), and Bu. quarlesi (the low mountain anoa) are endemic to Indonesia (Hernández and Vrba, 2005).

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examples on the details of dentition for this species, as the earlier authors only described skull remains (Falconer, 1868;Lydekker, 1878;Pilgrim, 1937); moreover, the previously reported specimens are recovered from the Indian Siwaliks.

MATERIALS AND METHODS
Most of the remains of Bu. platyceros described in this article were previously collected from the Sardhok locality and housed in the Dr. Abu Bakr Fossil Display and Research Centre, Zoology Department, University of the Punjab, Lahore, Pakistan. New material, including a hemimandible and isolated dentitions, have been collected as a result of recent excavations in the Sardhok area. Most of the specimens were fully exposed whereas small excavations were performed to retrieve the specimens that were only partially exposed. A digital Vernier caliper was used for the measurements of the specimens; the specimens were measured at their maximum length and width. Uppercase letters refer to the upper teeth and lowercase letters refer to the lower teeth. The specimens catalogue number (e.g. 2013/55) consists of numerator (collection year) and denominator (serial number). The photographs were taken with digital camera and the plates were prepared in Adobe Photoshop CC (trial version). The tooth terminology and measurement follow Gentry et al. (1999), as illustrated below (Fig. 1 (Pilgrim, 1937).

Description
General description for upper molars: The upper dentition includes first, second and third molars (Fig. 2). The molars are large and bulky. The enamel is rugose. The traces of depository material are present. The cingulum is absent. The cusps are more distinct labially. The protocone, hypocone, paracone and metacone are well developed. The protocone is comparatively robust and massive. A

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shallow vertical groove is present on the anterior side of protocone. Another shallow vertical groove is present on the posterior side of hypocone. The preprotocrista is larger than postprotocrista. The prehypocrista is smaller than posthypocrista. The slender metacone has pre-and postmetacristae of equal length. The entostyle is present between the protocone and hypocone. The entostyle is closer to hypocone as compared to protocone. The anterior and posterior median ribs are prominent. A vertical groove is present between the anterior rib and parastyle, which is narrow at the base and broad towards the apex. The mesostyle, parastyle and metastyle are broad at the base and gradually tapering towards the apex. The prefossette has a "U" shape appearance with an indentation present, whereas the postfossette shows indentations and a spur. Overall, the pre-and postfossettes are deep with minor indentations. The metastyle is comparatively robust in third molars than in second molars.
General description for lower dentition: The premolars have traces of cements labio-lingually. The p2 is in late wear and elongated (Figs. 2.3a-c). The anterior side is prominent occlusally. The parastylid is weakly developed. An anterior valley is present between parastylid and praconid and the posterior valley is present between the metaconid and entoconid, which is comparatively deep apico-basally. The base of entostylid is shelf like. The shallow vertical groove is present postero-labially as in the p3 and p4 (Fig. 3a-c). The p3 is longer than p2. The paraconid is bulky. The metaconid is and broad. The antero-posterior valleys are prominent and deep labially. The p4 has a vertical groove between protoconid and hypoconid. The entoconid, protoconid and metaconid are somewhat crescentic. The metaconid is distinct from the protoconid. The hypoconid is long. The metaconid and entoconid have lingual extensions. The lower molars are rugose ( Fig. 2.5, 2.7). The protoconid, metaconid, hypoconid and entoconid are well preserved. The preprotocristid is larger than postprotocristid. The pre-and posthypocristids are of same size as in pre-postentocristids. An ectostylid is present between the protoconid and the hypoconid. A shallow vertical groove is present between anterior median rib and metastylid. A wide and shallow vertical groove is present between posterior median rib and entostylid. The ectostylid is prominent and extends transversely. The prefossette is narrow with crescentic outline while the postfossette shows indentations and spurs. The metastylid is slender and divergent. The hypoconulids are located posteriorly on the lower third molars (Fig. 2.7a). The hypoconulid is conical and divergent posteriorly.
Mandible. PUPC 2010/01 is a right hemimandible with diastema, ascending ramus, coronoid and angular process retaining the complete series of premolars and ramus (Fig. 3). The mandible body is typical of bovine species; it is labio-lingually narrow, slender and long. The coronoid process is strong and wide, recurved backward Siwalik Bovidae

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and outward. The ventral posterior edges of the horizontal ramus are thick. The ascent begins right after m3, so there is no gap between the m3 and the ascending ramus. The internal and external surfaces of the jaw posterior to the m3 are marked by rugosities, representing muscle attachments. A pair of mental foramina is present labially, the dorsal one being smaller than the ventral one. The mandibular foramen is prominent lingually. The symphyseal surface is narrow posteriorly in dorsal view (Fig. 3-a1); it is quite robust in caudal view. The condylar and coronoid processes are damaged. There is a shallow open notch between the condylar and coronoid processes (Fig. 3-a1).
The comparative measurements of the hemimandible and the cheek teeth are given in Tables I and II, and are plotted in Figure 4.
The studied material differs from Hemibos, Proamphibos and Leptobos in having mediolaterallyexpanded mandible in the incisive region, and long and slender mandible behind the canines with relatively narrow lower teeth. Bos and other bovines have comparatively short p2 (Hooijer, 1958); the p2 described here is not reduced having well-marked meta-and entoconids. The long and slender mandible with long diastema associates it to the genus Bubalus (Pilgrim, 1937(Pilgrim, , 1939Hooijer, 1958;Akhtar, 1992). The elongated p2 is also one of the characters of the genus Bubalus. The mandible of Bubalus differs from that of Bos in being longer and more slender, higher at the cheek teeth, with a wider but relatively lower ascending portion; the coronoid process in Bubalus is wider and apparently more strongly recurved backward and outward than that in Bos (Stremme, 1911).
There are two species of the genus Bubalus in the Pleistocene deposits of the Siwaliks: Bu. platyceros and Bu. palaeindicus. Bubalus palaeindicus is related to the modern Indian buffalo (Bubalus bubalis), having large size (Falconer, 1868;Lydekker, 1878;Hooijer, 1958;Badam and Sankhyan, 2009). Metrically, the studied specimens are smaller than Bu. bubalis (domestic buffalo) and Bu. palaeindicus (Tables I and II, Fig.  4). The comparison to other buffalo species (Table  II) reveals that these specimens can be allied to Bu. platyceros (Pilgrim, 1937). The collected teeth represent all the characters of the Pleistocene subcontinental buffalo, which is indigenous to the Indian subcontinent: hypsodonty, slim mandible fragment and long p2 with prominent anterior valley (Pilgrim, 1939;Hooijer, 1958).

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Siwalik Bovidae

DISCUSSION
Bubalus platyceros was erected by Lydekker (1878) from the Siwalik Hills of the Indian subcontinent based on a cranium and partial horncores. Later, (Pilgrim, 1937) ascribed Bu. cf. platyceros, based on a skull from the Upper Siwalik Subgroup. Berckhemer (1927) while describing Bu. murrensis skull from Steinheim pointed out that it more closely resembles Bu. platyceros than the Recent Bu. arnee. Hooijer (1958) made comparison to Bu. platyceros and Bu. palaeokerabau, and noted that Bu. platyceros differed from Bu. palaeokerabau in having horn cores directed obliquely upward with triangular cross section. Koenigswald (1986) suggested that Bu. murrensis might be a junior synonym of Bu. platyceros. The latter species, Bu. platyceros, ranges from the middle to late Pleistocene of the Siwaliks (Nanda, 2008).
Synonymy: The new material of Bu. platyceros made it possible to review Bu. jarikasensis, recently erected by Akhtar (2002), based on a left mandible bearing the diastema of p3-m1 and well-preserved m2-3 from Jarikas, Mir Pur, Azad Kashmir, Pakistan. The description of Bu. jarikasensis was based on a single hemimandible bearing left p3-4 and m2-3 (PUPC 1991/10) and Akhtar (2002) noted that this hemimandible differs from other Bubalus species in having no p2 and there is a diastema between p3 and p4. The crowns of the premolars are missing and the root alveoli are preserved in this hemimandible. However, the absence of p2 is a developmental anomaly not an evolutionary point and such an anomaly has not been reported for Bubalus but has been observed in some specimens of primates, artiodactyls, and perissodactyls; like the absence of P2 in the left maxilla of Tayassu tajacu (Miles andGrigson, 2003, specimen number BMNH 1921.1.78), the absence of right M3 in the maxilla and right m3 in the mandible of Colobus polykomos satana (Miles and Grigson, 2003, 3.31, specimens number, P-C Mus. CamII483) and the absence of left m2-3 in the mandible of Dendrohyrax validus neumanni (Miles andGrigson, 2003, specimen number BMNH 1906.6.5.23). Normally, the crown is extended antero-posteriorly at the apex in bovines resulting in a space/gap at the base of teeth. Due to the absence of crown of premolars, this gap becomes visible between the root alveoli and such a gap can't be considered as an evolutionary point to erect a new species. Such is the case with the Bu. jarikasensis's mandible in which a gap appears between the p3 and p4 due to absence of the crown of these premolars.
Moreover, morphometrically, the studied hemimandible (PUPC 2010/01) has the same characteristics as PUPC 1991/10. The morphology and metric values of the teeth are consistent with that of Bu. platyceros (Table II;  is comparable with the potential size of a Bu. platyceros hemimandible (PUPC 2010/01). The characters such as missing p2 and presence of gap between alveoli of p3 and p4, are insufficiently diagnostic, as such features are entirely variable even within single individuals and does indeed vary intraspecifically (See Bibi and Güleç, 2008;Mennecart et al., 2011;Allouch, 2014;Kostopoulos and Karakütük, 2015;Suraprasit et al., 2016). Therefore, Bu. jarikasensis, erected by Akhtar (2002), is probably a junior synonym of Bu. platyceros. The material from Jarikas in Azad Kashmir and Sardhok is morphologically and metrically homogeneous. It can be referred to a single species Bu. platyceros.