Original Giraffokeryx punjabiensis (Artiodactyla, Ruminantia, Giraffidae) from Lower Siwaliks (Chinji Formation) of Dhok Bun Ameer Khatoon, Pakistan Khizar Samiullah1*, Muhammad Akhtar2, Abdul Ghaffar3, Muhammad Akbar Khan4 Received : 28 January 2011 ; Accepted : 13 September 2011 Abstract Fossil remains of Giraffokeryx punjabiensis (premolar and molar teeth belonging to the upper and lower jaws) have been collected and discussed from Chinji Formation of Dhok Bun Ameer Khatoon (32o 47’ 26.4” N, 72° 55’ 35.7” E). All these (twenty one) specimens are isolated teeth, which provide new data and give valuable information on the biostratigrphy and paleoecology of Giraffokeryx punjabiensis as well as the stratigraphy and paleoclimates of these Miocene rocks of the Chakwal district, Pakistan. Keywords: Giraffokeryx punjabiensis, isolated teeth, Chinji Formation, biostratigraphy Miocene rocks, Chakwal district. Introduction Dhok Bun Ameer Khatoon (DBAK) is poorly known fossil ramii and a number of isolated teeth. Mathew4 studied site of the Siwaliks. Previous pioneer workers 1,2,3,4,5 did the material of this species at the Indian Museum, not visit this site nor mentioned it in their faunal list. Kolkata (Calcutta), and recognized a larger and a During the last decade, this site had got attraction of smaller form. However, Colbert5 suggested there was researchers when few fossils were unearthed during a continuous size gradation of the dental material of the mechanical work for construction of dam for water the species through the Chinji to the Nagri Formation storage purposes. Girafids, bovids, tragulids, suids, and therefore that no such size division exists in the hominids, rhinos, chilothers anthracothers and carnivors material of the genus Giraffokeryx. Giraffokeryx is are the common elements of the fauna (unbpublished similar to Palaeotragus but has an extra pair of horn data) and very similar to Chinji stratotype in the Chinji cores on the frontals. Giraffokeryx followed a line area situated 50km due west. Fossil remains of of development that is different from other giraffids Eotragus sp. have been recently described by Khan6. through the evolution of it’s horn cores. In Giraffokeryx, Giraffokeryx punjabiensis, the type species of the the anterior horn arises from the frontal5. This Middle genus Giraffokeryx, was erected by Pilgrim2 on the Miocene genus7 shares several features with the basis of an isolated upper molar from the Chinji zone, Upper Miocene Palaeotragus, such as long, conical of the Lower Siwaliks of Pakistan. The species is now supra-orbital horns widely separated at the base, a known by several skulls, palatal fragments, mandibular much broader frontal compared to the occipital, with 1,2 Department of Zoology, Quaid-e-Azam campus, University of the Punjab, Lahore, Pakistan. 3 Department of Meteorology, COMSATS Institute of Information Technology (CIIT), Islamabad 4 Department of Zoology, GC, University, Faisalabad, Pakistan * Corresponding author: [email protected] 10 Samiullah K. J Sci Technol MSU the skull being long and low8. Giraffokeryx, along with feldspars, variable proportions of lithic grains accessory Progiraffa and Giraffa, are smaller forms of giraffid, of amounts of micas and traces of a number of heavy which Giraffokeryx was a mixed feeder. It disappeared minerals. The presence of appreciable amount of during the deposition of the Nagri Formation, perhaps feldspars in all the sandstone samples favors the around 10 million years ago, whereas during the rest arctic climate. The Chinji sandstone shows equal of Miocene, large giraffids remained present9,10,11. contribution of medium high grade and low grade The Siwalik giraffes may be placed in three subfamilies: metamorphic rocks provenance. Similarly a consistent the Palaeotraginae, Sivatheriinae and Giraffinae. The presence of mica, epidote and granet indicates that Palaeotraginae comprises the genus Giraffokeryx only. the Chinji Formation is composed of metamorphic The Sivatheriinae includes the genera Sivatherium, rocks. Similarly the high amount of non-undulatory Bramatherium, Hydaspitherium and Helladotherium monocrystalline than the undulatory one suggests the whereas the genus Giraffa is placed in the Giraffinae. presence of plutonic and volcanic rocks in Chinji area. All of these genera, except the genus Giraffa, were Furthermore, the intersectional variation in composition endemic to the Siwalik region.The palaeotragines and types of quartz grains in Chinji sandstones were present in Asia and Europe during the Miocene suggest a stony spatial control on their deposition16. Epoch12,13 and it is probable that Giraffokeryx evolved In general the Chinji Formation is dominantly composed from palaeotragines present in Asia. Giraffokeryx was of bright red and brown orange siltstone interbeded a medium sized giraffid with four horns: two at the with ash gray-sand stone (siltstone to sandstone ratio= anterior extremities of the frontals and two on the 4:1) in the type section. The interbeded in-channel fronto-parietal region. Giraffokeryx chinjiensis was and over bank siltstone sequences are 10-50 meter described by Sarwar14 from the Chinji type locality in thick that are complexly stacked both vertically and Punjab, Pakistan and is based upon three different laterally17. Chinji Formation is described with reference upper molars of different individuals. The difference to four units. The bottom unit consists of interbeded between the two is in morphology of the teeth: the sandstone, silt clay and siltstone followed by a unit styles are strong and the median outer rib of the predominantly composed of sandstone containing paracone is well developed in Giraffokeryx chinjiensis. subordinate beds of siltstones and silty clay and the topmost unit is mostly silty clay and claystone containing Geology and stratigrphy yellowish- gray medium to course-grained sandstone DBAK area contains an almost continuous geological at the base18. Based on the magnetic stratigraphic record spanning approximately 18.5ma- 4.5BP15. studies in Potwar 14.3 Ma and 10.8Ma are interpreted The Siwalik group in this area is composed of five tobe the ages of the lower and upper contacts of the lithostratigraphic units which are kamlial, Chinji, Chinji Formation respectively19. On the basis of different Nagri, Dhok Pathan and Soan Formation. The overall fauna, the age of the formation is considered tobe lithological composition of these component formations late Miocene20. Lithofacies of the Chinji Formation are are fairly identical with those described for their type thought to represent deposits of either the Paleo-Indus sections but however are relatively less thicker and River or a similar axial fluvial system15. The multistoried contain more mud stones. Chinji Formation has its good channel type sandstone-bodies of Chinji Formation exposure in DBAK area and is in strike continuation suggest a consistent flow direction to the SSE21. There with its stratotype in Chinji area (This paper). Chinji are broad similarities between channel geometrics, Formation dominantly consists of sandstones and discharge and sedimentary characters of Siwalik rivers shales. Detailed peterographic studies of Chinji and modern Indus river system including emergence sandstones contains abundant quartz with subordinate from mountain belt, generally parallel flow to the basin Vol 31, No 1, Jun-Feb 2012 Giraffokeryx punjabiensis (Artiodactyla, Ruminantia, Giraffidae) from Lower 11 Siwaliks (Chinji Formation) of Dhok Bun Ameer Khatoon, Pakistan axis, slopes range and bankfull discharge22. Inspite of World26,27,28,29,30. Today the family Giraffidae is only adequate exposure of Chinji Formation in the DBAK, represented by two species Okapia johnstoni and Giraffa fossils are not easily found in this area as compare to camelopardalis, both these are found in Africa. Okapia Chinji stratotype. It is particularly because of steeper johnstoni is present in limited area of heavy forests dips and some structural complication, thus reducing in West Africa, whereas the Giraffa camelopardalis is the area of exposure per bed and also an increase found in the more open parts of Sub-Saharan Africa. in mudstone indicates existence of floodplains, which relatively have less potential for fossilization. Paleoclimate and diet adaptation The Giraffokeryx remains in this study document the Paleoecology and biostratigrphy vegetation of Chinji Formation as seasonal woodland The primitive giraffid,Georgiomeryx appeared in MN5 with riparian areas of forest. The occurrence of (17Ma)23, with unbranched and short horns. From MN6 Giraffokeryx punjabiensis from Chinji – Nagri Formation (16Ma) to onward, the known giraffid hitherto in Europe testifies a change in the composition of the Siwaliks are assigned to Giraffokeryx Pilgrim3. The features of from seasonal woodland – tree savannas. Giraffokeryx Giraffokeryx that are advanced over Georgiomeryx Punjabiensis was a mixed feeder and is well adapted are higher cheek teeth, upper molars with less of a to a life in savannas. They drink water when it is basal pillar and lingual cingulum, labial wall of the available but can go weeks without it. They rely on metacone more upright on upper molars, lower molars morning dew and water content of their food31,29,32,33. with less prominent metastylids in earlier wear and The diet of fossil Giraffidae was until recently thought small entostylids, frequent fusion of praemetacristid to be similar to that of extant giraffes (committed with postprotoconulidcristid