Siwalik synopsis: A long stratigraphic sequence for the Later Cenozoic of South Asia

The Tertiary sediments of northern Pakistan are an exceptional record of terrestrial sedimentation and represent most of Neogene time. Foremost is the Siwalik Group of the Potwar Plateau, for which multiple, superposed fossil levels span ∼18–6 Ma. Well-developed magnetostratigraphic control provides secure dating so that Siwalik fossil horizons may be interpolated into a time scale with resolution to 100,000 years. We describe the geographic setting of the Potwar, give an overview of the temporal distribution of faunas, and discuss changes in paleohabitat and paleoecology with coinciding faunal change, as seen from the Siwalik viewpoint. The long Siwalik biostratigraphy of many successive assemblages with its resolved time scale may be compared directly with other well-dated sequences. Immigrant arrival and timing of faunal change may be traced. The basins of the Iberian Peninsula show somewhat different timing of introduction of hipparionine horses, and faunal turnover in the Siwaliks clearly precedes the Vallesian crisis in Spain. In contrast to the increasingly seasonal precipitation of the late Miocene Potwar, the paleohabitat of coeval North China appears to have been moist and equable, with high diversity faunas. Continued development and comparison of resolved Neogene records allow increasing resolution of the patterns of faunal change on regional to global levels.     

New Bovid fossils from the Late Miocene Hasnot (Siwaliks,Pakistan)

The Siwalik Late Miocene bovids from the Hasnot deposits of Northern Pakistan are described here. The bovids are represented predominantly by boselaphines. The Hasnot outcrops range 7–5 Ma and correspond to the fauna of the Late Miocene–Early Pliocene of Eurasia and Africa. The associated fauna of Hasnot is suggestive a vast open land environment depicting sporadic dry and flood seasons, forcing a mosaic of ecotonal habitats with countless number of niches.     

Amphibians and squamates from the Neogene Siwalik beds of Jammu and Kashmir, India

The Neogene Siwalik deposits of Jammu Province (India) have yielded amphibians and squamates. The collection includes the first amphibians and the first colubroid snakes from the Siwalik Group. Amphibians comprise only anurans: a possible Ranidae and one, or perhaps two, non-ranid frogs Squamates include one lizard,Varanus sp. (Varanidae), whereas snakes are represented by three taxa:Acrochordus dehmi (Acrochordidae), an indeterminate Colubridae, and a snake that is either a Colubridae or an Elapidae.Varanus sp. andA. dehmi have been yielded by the Upper Miocene Ramnagar Member, whereas the anurans and colubroid snakes come from the Upper Pliocene Labli Member. These taxa are indicative of aquatic palaeoenvironment.     

Magnetic polarity stratigraphy and ages of Siwalik group rocks of the potwar plateau,Pakistan

Six magnetic polarity sections have been established over the Potwar Plateau region of Pakistan, including the major stratotypes of the Siwalik Group. In all six sections the dominant feature of the magnetic polarity stratigraphy is a long normal polarity zone, which is contained within the Nagri Formation. This conspicuous normal polarity zone has been radiometrically dated at 9.5 ± 0.6 m.y., which identifies it as magnetic Chron 9. Radiometric dates from the Upper Siwalik Formation have also been used to identify the Chron 2–3 boundary in two of the sections. The magnetic polarity stratigraphy of three of the sections has been correlated securely with the accepted magnetic polarity time scale, so that the ages of the local stratigraphy are indexed accordingly. Based exclusively on data from stratotype sections, the Chinji, Nagri and Dhok Pathan Formations have nominal age ranges of 10.1–13.1, 7.9–10.1 and 5.1–7.9 m.y. Age fluctuations on the order of 10⁵ years may be anticipated for these formational boundaries within radius of some 20 km of the designated stratotype. Mean sediment accumulation rates during the Chinji, Nagri and Dhok Pathan interval range from 13 to 52 cm/10³ yr.Essentially linear sediment accumulations are locally maintained over time intervals of several million years. The Chinji-Nagri lithofacies boundary marks a transition from slow to faster sediment accumulation over much of the Potwar Plateau, indicating a fundamental sedimentary-tectonic change at this time.     

A time framework based on magnetostratigraphy for the siwalik sediments of the Khaur area,Northern Pakistan

The magnetostratigraphy of eleven new sections in the Khaur area of northern Pakistan is presented. All specimens have been subjected to thermal demagnetization. The sections, taken in adjacent ravines incising the Siwalik formations nearly penpendicular to strike, form a temporal framework in which to interpret the biological and lithological information. A composite section is constructed from several long sections and is correlated to the magnetic polarity time scale (Chron 6 to Chron 15), providing absolute age information for the biostratigraphic zonations of Barry et al. (1982). Detailed sections along the strike of major stratigraphic marker beds document an isochronous horizon and form the basis for paleoenvironmental reconstructions. The preservation of a polarity transition in fluvial sediments suggests continuity of sedimentation on a time scale of 10³–10⁴ years.     

Systematic revision of Siwalik Rhizomyidae (Rodentia)

Larges samples of fossil rhizomyids from the Siwalikmolasse deposits of the Potwar Plateau, Pakistan, enable reevaluation of fossil taxa and their evolutionary relationships. Siwalik Rhizomyidae constitute a basis for analysis of poorly represented rhizomyids from other areas in Asia and contribute to biochronological correlation. The extant Tachyoryctinae and Rhizomyinae diverged during the early history of the family and diagnoses of the subfamilies are amended to include extinct genera. Siwalik tachyoryctines include Kanisamys, Protachyoryctes, Rhizomyides, and Eicooryctes nov. gen.; rhizomyines are Brachyrhizomys and Anepsirhizomys nov. gen. Kanisamys, the earliest Siwalik rhizomyid, appeared by about 13 Ma and evolved slowly, displaying stasis in K. sivalensis. Brachyrhizomys evolved from Kanisamys by 9.5 Ma and radiated rapidly. B. nagrii displays rapid increase in size through time. About 7 Ma, Kanisamys and Brachyrhizomys became extinct locally and Protachyoryctes, Eicooryctes, and Rhizomyides appeared, perhaps in response to increasing aridity. After 5.5 Ma, rhizomyids became uncommon in the Potwar and Anepsirhizomys (3.0 Ma) constitutes the latest record of Rhizomyidae in Pakistan.     

Soanian lithic occurrences and raw material exploitation in the Siwalik Frontal Zone, northern India: a geoarchaeological perspective

In the Himalayan foothills of northern India, evidence of widespread hominin occupation since at least the late Middle Pleistocene has been known since the early 20th century and indicates varied patterns of land-use and intraregional mobility. This lithic evidence primarily belongs to the Soanian industry, representing some of the highest concentrations of Paleolithic assemblages in the Old World based exclusively on pebble and cobble clasts. This body of evidence also signifies interregional dispersal from peninsular India or northern Pakistan, leading to environmental preferences that spread quickly through hominin populations in the region within a relatively short timespan. While rich in its technological repertoire, the Soanian industry is poorly- understood regarding site selection and raw material exploitation over time. Recent efforts demonstrate that Soanian sites on Siwalik frontal slopes between two major rivers vary considerably in their artifact quantities regardless of abundant raw material sources found across the landscape. Most of the assemblages suggest raw material transport distances of three kilometers or less from the localized sources. Geoarchaeological investigations at the richest known Soanian site, Toka, reveal dynamic evidence of pre- and postdepositional site formation including the exploitation of quartzite pebbles and cobbles by Pleistocene hominins from terrace and streambed contexts within a 1 km2 radius. Some field observations also disprove claims made by previous workers, of artifacts eroding out of late Pliocene exposures of the Upper Siwalik Tatrot Formation around Toka.     

Cricetid rodents from the Lower Siwalik Subgroup of Jammu,India: Biochronological significance

We describe the cricetid rodents represented by Megacricetodon daamsi, Megacricetodon sivalensis, and Myocricetodon sivalensis, recovered from two localities, Dehari and Jhajjar Kotli, lying in the upper part of the Lower Siwalik Subgroup of Jammu Province. The cricetid fauna is similar to that reported from the Pakistan Siwaliks. Based on the species identifications and the stratigraphic range of the cricetid taxa in the Siwalik succession of Pakistan, the age of the Dehari locality is correlated to between 13.8 and 13.2 Ma, whereas an age of 13.8–12.5 Ma would be assigned to the Jhajjar Kotli rodent yielding level. The occurrence of similar rodent taxa at the two investigated sites points to the homotaxial nature of the fossiliferous beds.     

Pleistocene rapid uplift of the Himalayan frontal ranges recorded in the Kathmandu and Siwalik basins

Core-drilling project carried out in the southern margin of the Kathmandu Basin revealed that muddy debris flow deposits dammed up the Proto-Bagmati river to form the Paleo-Kathmandu Lake during the Jaramillo subchron from 1.07 to 0.97 Ma. Subsequent deposition of the alluvial fanglomerate, derived from the uplifting Mahabharat Range to the south, raised the dam deepening the lake-water. After 1 Ma, in the southern part of the basin, palaeo-current directions changed from southward to northward and deposition of gneissose and granitic detritus are replaced by meta-sediments derived from the Mahabharat Range.During the same time, at about 1 Ma, the boulder conglomerates were deposited on top of the Siwalik Group as piggy-back basins in front of an intra-basinal high, along the Main Dung Thrust in Nepal and NW India. Onset of movement of the Main Dung Thrust is dated back to 3 to 2.4 Ma [Mugnier, J.L., Huyge, P., Leturmy, P., Jouanne, F., 2003, Episodicity and rates of thrust-sheet motion in the Himalayas, Western Nepal. Am. Assoc. Petrol. Geol., Mem. 82, 1-24]. The Main Frontal Thrust is most active at present suggesting that imbricated structure of the Siwalik Group was formed by convergence of the Indian plate during the last 3 myr. The accretionary wedge of the Siwalik Group, stacked beneath the Main Boundary Thrust, might have started to jack up the frontal range of the Lesser Himalaya since 1 Ma.Coeval uplift and erosion of the frontal range of the Lesser Himalaya and the intra-basinal high in the Siwalik since 1 Ma are possible causes of an abrupt increase in both sedimentation rate and grain size of detrital quartz, and changes in composition of clay minerals, recorded in the sediments of the Bengal Deep Sea Fan at 0.9 Ma.     

Miocene hyaenids (Hyaenidae; Carnivora) from Siwaliks of Pakistan

Newly discovered Miocene hyaenid specimens, recently collected from the Siwalik Group, are described and discussed. A careful comparison with the known material reveals that these specimens belong to the early hyaenid species Thalassictis cf. T. proava, Ictitherine indet. and Lepthyaena sivalensis. The stratigraphic range of T. proava extended up to the Dhok Pathan Formation (Middle Miocene to Early Pliocene). The stratigraphic range of T. proava comprises the Middle to Late Miocene, with the youngest record in Hasnot, Potwar Plateau in the Siwalik Group. The material is of great interest because Siwalik carnivoran material is rare.     

Palaeogene palaeobiogeography of the Indian subcontinent

Certain palaeoecological criteria in the reconstruction of the Palaeogene palaeobiogeography of the Indian subcontinent are discussed. The Early Palaeogene is characterised by marine oscillations, a prolific invertebrate fauna, extensive coal facies development and outpouring of basaltic lava flows, the last being a feature connected with the movement of the Indian Plate and coinciding with a Himalayan orogenic impulse. The Middle Eocene transgression marks the transition of marine sedimentation to fluvial conditions in northern India with the presence of a fairly diverse mammalian fauna in northwestern Pakistan and northern India. During the Late Oligocene, mammals clearly ancestral to the much more prolific Siwalik fauna were present in western Pakistan, northeastern India and southcentral Burma.The flora consists of mainly tropical to subtropical families with the addition of some temperate elements in Assam in the latter half of the Eocene and Oligocene. Invertebrates indicate a close affinity between the western and eastern sectors and suggest that the sea was continuous in the north at least up to the Palaeocene. With the emergence of land in the northeastern part of the subcontinent, the fauna of Assam acquired distinct Indo-Pacific elements similar to those of Burma and the Indonesian Arc. Later, the sea was divided into two gulfs which gradually shrank towards the end of the Palaeogene and disappeared by the Middle Miocene.     

Boselaphines (Artiodactyla, Ruminantia, Bovidae) from the Middle Siwaliks of Hasnot, Pakistan

In this paper, boselaphine material from several localities in the area of the Hasnot Pakistan, is described, identified, and discussed. Four species that belong to three different genera of the tribe Boselaphini have been found: Selenoportax vexillarius, S. lydekkeri, Pachyportax latidens and Eotragus sp. Eotragus sp. is reported for the first time from the Hasnot and consequently from other Upper Middle Siwalik sediments of Pakistan and equivalent strata of the world, extending the range of the genus from the Lower to the Middle Siwaliks. Reviewing the Siwaliks’ Selenoportax species, S. dhokpathanensis Akhtar and S. tatrotensis Akhtar are synonymized with S. lydekkeri and S. vexillarius, respectively.     

Early Paleogene decapod crustaceans from the Sulaiman and Kirthar Ranges,Pakistan

A set of Paleocene and Eocene decapod crustaceans is described from the Sulaiman and Kirthar Ranges of Pakistan. The fossil crabs Proxicarpilius planifrons Collins and Morris, 1978 and Pakicarcinus orientalis (Collins and Morris, 1978), already known in the Eocene of northern Pakistan, are reported for the first time in the Paleocene of southern Pakistan, enlarging the stratigraphic and the palaeobiogeographical ranges of these species. The callianassid genus Calliax de Saint Laurent, 1973 is reported for the first time in the Paleocene of southern Pakistan; this is the oldest record for the genus.     

Cytogenetical survey of black rats,Rattus rattus,in southwest and Central Asia,with special regard to the evolutional relationship between three geographical types

A chromosome survey of the black rat, Rattus rattus, was made from animals collected at different localities in Southwest and Central Asia. Asian type black rats (2 n=42) were distributed in northern India, northern Pakistan, while the Oceanian type rats (2 n=38) were found in southern India, southern Pakistan and Central Asia. A border line of distribution of rats with Asian and Oceanian types can be drawn dividing India and Pakistan into northern and southern parts. A hybrid type between Asian and Oceanian types was found in Karachi, Pakistan. Rats with 40 chromosomes, probably a transient type from Asian to Oceanian type, were found in Sri Lanka (Ceylon). It is suggested that these three geographic variants have developed via sequential events of Robertsonian fusion of acrocentric chromosomes in Asian type black rats. This fusion probably took place somewhere in southern India. The Oceanian type black rats that thus developed in southern India migrated widely to the rest of the world through Central Asia and Europe accompanying the movement of mankind.     

New small mammals from the Hasnot–Tatrot area of the Potwar Plateau,northern Pakistan

New rodent and lagomorph fossils from the Hasnot–Tatrot area of northern Pakistan are presented here to complement knowledge of stratigraphic ranges and morphology of key late Neogene Siwalik taxa. Most of the material is from two sites near the village of Bhandar in strata of the late Miocene age Dhok Pathan Formation; one specimen comes from the Pliocene Tatrot beds. We apply previously established magnetostratigraphy to date the fossils, the Bhandar sites dating to 6.6–6.7 Ma. In describing the fossils, we emphasize new morphological information represented by the material. As surface finds, these fossils represent relatively large body size species: three bamboo rat relatives, a porcupine, and a rabbit. The bamboo rats (Rhizomyinae) are an endemic group, and both the porcupine (Hystrix) and the rabbit (Alilepus) represent late Miocene immigrants into the Indian subcontinent.     

A canine tooth from the Siwaliks: first recorded discovery of a fossil ape?

Archival research reveals that it is highly probably that the first discovery of a fossil ape was made by Hugh Falconer and his associates in the 1830s during surveys of Neogene deposits in the Siwalik hills of British Colonial India. However, priority is commonly awarded to Edouard Lartet who, in 1837, brought to light a fossil primate specimen from the Miocene beds at Sansan in France to which Paul Gervais gave the namePliopithecus. Falconer's letters and scientific papers announcing the find of a fossil primate group from the Siwalik Hills were antecedent to Lartet's report to the French Academy of Sciences, Paris. The circumstances surrounding this misconception over priority of discovery of fossil apes are reviewed with attention to the historic significance of the Siwalik fossil primates and with respect to the development of paleoanthropology in South Asia.     

A new species of the genus Microbunodon (Anthracotheriidae, Artiodactyla) from the Miocene of Pakistan: genus revision, phylogenetic relationships and palaeobiogeography

Lihoreau, F., Blondel, C., Barry, J. & Brunet, M. (2004). A new species of the genus Microbunodon (Anthracotheriidae, Artiodactyla) from the Miocene of Pakistan: genus revision, phylogenetic relationships and palaeobiogeography. — Zoologica Scripta , 33 , 97–115.
New unpublished remains of small Anthracotheriinae are described. First, materials from the upper Oligocene (MP 30) locality of La Milloque, southwest France, permit a review of the species Microbunodon minimum . Thereafter, fossils from the middle and late Miocene of the Potwar Plateau, Pakistan are attributed to the European genus Microbunodon . Microbunodon milaensis sp. n. from the Nagri Formation (between 10.3 and 9.2 Ma), Pakistan, is described and the species M. silistrensis from the Lower Manchar Formation (between 16 and 15 Ma) and from the Chinji Formation (between 12.7 and 11.5 Ma), Pakistan, is reviewed. The new species represents the last occurrence of the subfamily Anthracotheriinae, around 9.3 Ma. Similar materials from the Bugti and Siwalik Hills were previously considered as a small Anthracotherium . Comparisons with M. minimum from the European late Oligocene lead to a complete revision of the genus and permit definition of a new set of characters, which separate Microbunodon from Anthracotherium . A cladistic analysis reconsiders phylogenetic relationships among Anthracotheriinae, separating an Anthracothema–Anthracotherium clade and an Anthracokeryx–Microbunodon clade. Microbunodon appears to stem from the Asian late Eocene–lower Oligocene genus Anthracokeryx . These results imply a new distribution of the genus Microbunodon showing exchanges between Europe and Asia during the late Oligocene and probably the lower Miocene.     

First Report of 'Candidatus Phytoplasma asteris' (Group 16SrI) Infecting Fruits and Vegetables in Islamabad, Pakistan

Nearby fruit and vegetable fields in Islamabad, Pakistan were surveyed for phytoplasma infection. ' Candidatus Phytoplasma asteris' (Group 16SrI) was found infecting mango, citrus, loquat, geranium, periwinkle, radish, blackberry and potato. Results suggest that a polyphagous vector may be involved in phytoplasma transmission to these plant species, which are first host records of 16SrI phytoplasma infection in Pakistan.