Middle Siwalik Research Articles

A new epifoliar melioloid fungus from the Siwalik (Miocene) of Himachal sub-Himalaya and its palaeoecological implications

A new fossil epifoliar ascomycete (Ascomycota), Meliolinites miocenicus nov. sp. (fossil Meliolaceae), occurs in situ on a compressed monocot leaf from middle Siwalik (Late Miocene, ca. 12–8 Ma) sediments of Himachal Pradesh, Western Himalaya. The fossil consists of a well-preserved mycelium of superficial, brown to dark brown, septate, thick-walled, branched hyphodiate hyphae; a sub-globose, dark brown putative ascoma, and an oblong to broadly cylindrical, five-celled, four-septate, mature germinating ascospore. The new fossil differs from earlier reported melioloid fossils primarily in the morphology of appressoria. Meliolinites miocenicus nov. sp. on its host is evidence of the existence of a biotrophic relationship at the time of deposition. Qualitative climate data using plant megafossils recovered from the same fossil locality indicate that M. miocenicus nov. sp. and its host thrived in a warm and humid tropical environment.

Fossil record of Meliolaceae from India sheds new insight into its taxonomy and life cycle

The asexual morph of Meliolaceae has long been a focus of attention for mycologists because there has been a lack of research to establish the asexual morph cycle of Meliolaceae. Besides asexual morph, only a few research works have also been done on the setae (mainly ascomatal setae) of Meliolaceae. In this connection, the use of reliable fossil evidence in evolutionary studies is obligatory. The present study fills this lacuna by reporting the in-situ occurrence of a new enigmatic fossil-genus and species Palaeomeliola indica Kundu and Khan, gen. et sp. nov. with mycelial setae, ascomata, ascomatal setae, ascomatal conoid cells, 4-septate ascospores, phialides, and phialoconidia on the cuticle fragments of a compressed disease-symptomatic monocot leaf recovered from the middle Siwalik (Late Miocene; ca. 12–8 Mya) of Himachal Pradesh, western Himalaya. Palaeomeliola indica is the first fossil-species of Meliolaceae having all sexual and asexual morphs. From this point of view, our new fossil fungus is very distinctive and establishes the greatest preserved fossil record of Meliolaceae. The preserved sexual and asexual morph data sheds new insight into the systematics, life cycle, and evolutionary lineages of Meliolaceae. Furthermore, the findings of this study will form the basis for any future life cycle reconstruction and morphological character evolutionary study of Meliolaceae.

New records for the Middle Siwalik flora of eastern Nepal and their climatic significance

The Siwalik plant fossils are important in understanding the climate change caused by the uplift of the Himalaya. The plant fossil assemblages are abundantly known from Nepal's central and western Siwalik sediments. However, they are poorly known from the Siwalik of the eastern region from where the modern Indian Summer Monsoon (ISM) enters Nepal. That is why fossils of this region are important in understanding the evolutionary history of ISM in Nepal. In the present communication, we report four new fossil leaf impressions/ compressions, namely Thelypteridaceophyllum tertiarum Joshi and Mehrotra of the family Thelypteridaceae, Calophyllum suraikholaensis Awasthi and Prasad of the Calophyllaceae, Albizia siwalica Prasad of the family Fabaceae, and Daphnogene makumensis Mehrotra, Dilcher et Lott of the family Lauraceae from the well-dated Middle Siwalik (∼9.5 Ma) sediments of eastern Nepal. The aforementioned and previous fossil records suggest that seasonal or monsoonal rainfall was present during the deposition of the sediments.

Fossils can reveal a long-vanished combination of character states: Evidence from a mysterious foliicolous anamorphic fungus from the Middle Siwalik (Late Miocene) of Himachal Pradesh, India

ABSTRACT Fossils can unveil a long-vanished combination of character states that inform inferences about the timing and patterns of diversification of modern fungi. By examining the well-preserved stacked chained vesicular conidiophores developed in clusters from the basal stroma, we describe a new taxon of fossil Zygosporiaceae with a combination of characters unknown among extant taxa on compressed serrated-margined dicot leaf (cf. Fagaceae) recovered from the Siwalik sediments (Late Miocene; ca. 12–8 Ma) of Himachal Pradesh, western Himalaya. Based upon conidiophore morphology, our Siwalik fungal remains, similar to Zygosporium Mont. (Zygosporiaceae: Xylariales: Sordariomycetes), are recognized as a new fossil species, Z. stromaticum Kundu & Khan, sp. nov. Zygosporium stromaticum is the only known fossil anamorphic fungus that occurs on plant cuticles and has a cluster of stacked chained vesicular conidiophores arising from a poorly preserved basal stroma formed by irregular, thick-walled cells. Its combination of morphological characteristics is unknown in extant fungal taxa, so Z. stromaticum likely represents a new anamorphic foliicolous fungus that may now be extinct. This unique evidence may be essential for the calibration of divergence time estimations of fungal lineages.

Fig leaf from the Middle Siwalik sediments of eastern Nepal with implication on biogeography and palaeoclimate

The Siwalik flora is important in understanding the orogeny of the Himalayas and the resulting climate change. Though the fossil records from the eastern Himalayan Siwalik of Nepal are sparse, we report a fossil leaf impression/ compression of Ficus precunea Lakhanpal from the Middle Siwalik (upper Miocene–lower Pliocene) sediments of eastern Nepal. The characteristic leaf venation pattern and morphological details suggest its strong affinity with the extant species of F. semicordata Buch.-Ham. ex Sm. The fossil assemblage indicates the presence of seasonal forests during the depositional period in the region.

Engineering Geological Study of Road Tunnel Along Siddhartha Highway Between Butwal and Dobhan Siwaliks Group, West-central Nepal

The Siddhartha Highway is a critical economic artery in Nepal, providing a vital trade link with China and India. However, this roadway has been beset by the frequent occurrence of rock falls and dry landslides, which can cause severe damage and disruption. The main causes of these issues are differential weathering patterns of the rocks, activation of the Main Frontal Thrust (MFT), and a young mountain chain with fragile geology. Because of road instability, the road tunnel has been proposed to prevent damage. The proposed tunnel road passes between the chainage of 29+000 and 30+370 in the rocks of the Lower and Middle Siwaliks. The Lower Siwaliks are composed of thick to thin-bedded shale, mudstone and calcareous sandstone whereas the Middle Siwaliks are represented by presence of friable sandstone, shale and mudstone. The rock mass of this section varies from poor rock to extremely poor rock with RMR values ranging from 29 to 45 and Q values ranging from 0.19 to 1.11. The support system for each class is derived according to RMR and Q-value. The kinematic analysis reveals the potential of wedge failure at the southern portal of the road tunnel, whereas the northern portal has shown a low potential for failure.

The Concretions from the Middle Siwalik Group of Eastern Himalaya around Buxa Tiger Reserve (BTR), Alipurduar, West Bengal, India

The Concretions from the Middle Siwalik Group of Eastern Himalaya around Buxa Tiger Reserve (BTR), Alipurduar, West Bengal, India

The first evidence of saprophytic Tetraploa on Siwalik (Late Miocene) monocot leaf from western Himalaya and its role in palaeoecology reconstruction

Even though the records of Tetraploa spores from Mesozoic and Cenozoic sedimentary strata along with spore-pollen assemblages are numerous and well documented, no foliicolus Tetraploa macroconidia have been reported to date. Here, we report the first occurrence of conidia assignable to modern Tetraploa Berk. & Broome (Tetraplosphaeriaceae: Pleosporales: Dothideomycetes) on cuticular fragments of compressed monocot leaf recovered from the middle Siwalik sediments (Late Miocene; 12–8 Ma) of Himachal Himalaya, India. We determine their taxonomic position based on detailed macromorphological comparison with similar modern and fossil taxa and discuss their palaeoecological significance in terms of the present-day ecological conditions of modern analogues. This finding also represents an essential data source for understanding Tetraploa's evolution and diversification in deep time.

First report of fossil representative of Zygosporium mont. With stacked chained vesicular conidiophores from India

In the present manuscript, we describe and illustrate a novel foliicolous fossil-species of Zygosporium Mont. (Zygosporiaceae: Xylariales: Sordariomycetes) on compressed monocot leaf recovered from the Middle Siwalik sediments (Late Miocene) of Himachal Pradesh, western Himalaya. The new fossil-species characterized by macronematous, dark brown, unbranched or occasionally branched conidiophores with a chain of up to four integrated dark brown, curved, thick-walled, swollen, hook-like, alternately or sub-oppositely arranged vesicles is described here as Zygosporium himachalensis sp. nov. This is the first fossil evidence of Zygosporium having stacked chained vesicular conidiophores and is so significant data for both paleomycologists and mycologists. The in-situ occurrence of Z. himachalensis on monocot leaf cuticles suggests a possible host–saprophyte relationship that might have existed in the ancient forest of Himachal Pradesh during the Miocene.

New fossil remains of Bovids from the Middle Siwaliks of Punjab, Pakistan

ABSTRACT A detailed taxonomic study of fossil mammals from five different localities including Nagri, Padhri, Markhal, Dhok Pathan type locality and Hasnot, from the Miocene of Middle Siwalik, Punjab, Pakistan, has been conducted. Bovidae described here are represented by thirty-six specimens including horns core, isolated teeth, fragments of maxilla and mandibles. Thirteen specimens belong to Gazella lydekkeri, including one horn core which are described first time from the Padhri and Markhal localities. Additionally, ten specimens belong to Pachyportax latidens and three specimens belong to Selenoportax vexillarius. Quantitatively, the bovids were more distributed than other taxa, provide evidence of medium (Gazella) size bovids from the Middle Miocene mammalian fauna. The palaeoenvironment of Nagri Formation was most humid with extensive forest and grasslands, while Dhok Pathan Formation has fluvial deposits indicating a wetland environment with mosaic of marshes, forests and woodlands. The dominance of fossil specimens of family Bovidae suggests an extremely moist environment with small, abundant standing water bodies. Biogeographically, the Miocene mammalian fauna of the Middle Siwalik resembled to Eurasian and African Miocene fossil localities. The composition of fauna from our studied sites suggests Late Miocene age. The described fossil remains indicate that large-sized fauna was present here during the Miocene.

New sivatheriine giraffid (Ruminantia, Mammalia) craniodental material from the Siwaliks of Pakistan

ABSTRACT We present a new taxonomic study of fossil giraffids from the Siwaliks of Pakistan. The recovered material belongs to the family Giraffidae and includes a cranium of Vishnutherium priscillum, maxillary isolated cheek teeth of Bramatherium grande, maxillary isolated cheek teeth and mandibular fragments of Bramatherium megacephalum. These specimens were collected from the localities of Dhok Bun Ameer Khatoon, Chakwal district, and Hasnot, Jhelum district, Punjab, Pakistan. These outcrops belong to the Chinji Formation and Dhok Pathan Formation, respectively, of lower to middle Siwaliks, dated as Middle to Late Miocene in age. The presence of fossil fauna that primarily fed on herbaceous, grassy, and bushy vegetation suggests that both Dhok Bun Ameer Khatoon and Hasnot were dominated by mixed woodland habitats. These localities have a very rich fossil fauna and the cranium of Vishnutherium priscillum is the first that has been reported from Dhok Bun Ameer Khatoon.

New suid remains of genus Propotamochoerus from the Siwaliks of Pakistan

Siwaliks of Pakistan are highly fossiliferous and are well-known worldwide for vertebrate fossil excavations. Objective: A field survey was conducted to recover some new fossils from different geological formations visible around the village Hasnot of district Jhelum. Methods: The targeted area was surveyed, and the different formations around the village were keenly examined by the naked eye or by using a magnifying glass when and where needed. Results: New dental remains of the genus Propotamochoerus (Mammalia, Suidae) have been found and described from the Middle Miocene Siwalik beds around Hasnot. The material consists of an isolated tooth, the left third mandibular molar. The genus Propotamochoerus was comprised of small to large-sized suids. Its remains were reported from the Lower to the Middle Siwaliks. The presently described material, i.e., a lower third molar of the left side, sheds a great deal of light on the fundamental dental characteristics of this genus. Conclusions: The recovered material is assigned to the species Propotamochoerus salinus (Pilgrim) based on its morphological assessment. This material can potentially enhance the prevalent knowledge of the species reported from the surroundings of the Salt Range of the Siwaliks of Pakistan.

Black mildew disease on the Siwalik (Miocene) monocot leaves of Western Himalaya, India caused by Meliolinites

We have recovered disease-symptomatic monocot leaves from the middle Siwalik (late Miocene; 12–8 Ma) sedimentary strata of Himachal Pradesh, western Himalaya, India. Information about disease symptoms linked to fossil monocot leaves, however, is lacking. The present study therefore aims to elucidate their identity through the analysis of morphological characteristics of the plant pathogenic fungi (causal agent) associated with these disease symptoms. Black mildew disease caused by foliicolous fungal fossil-genus Meliolinites Selkirk ex Janson. and Hills (fossil Meliolaceae) is detected on infected host Siwalik monocot leaves. In the study presented here, we provide formal descriptions and illustrations for the fossil-genus. The pathogen Meliolinites is recognized by the presence of appressoria, phialides, mycelial seta, black non-ostiolate ascomata, and four-septate, five-celled ascospores. This is the first report of melioloid fungus causing black mildew disease on fossil monocot leaves. Here, we also reconstruct a possible disease cycle of black mildew pathogen on Siwalik monocot leaves. The in-situ evidence of Meliolinites on the monocot leaf cuticles indicates the possible existence of a biotrophic relationship in Himachal sub-Himalaya's ancient warm and humid tropical forest during the time of deposition.

New Suid remains of genus Listriodon from the Siwaliks of Pakistan

New dental remains of the genus Listriodon (Mammalia, Suidae) have been found and described from the Lower to Middle Miocene Siwalik beds located around Hasnot, district Jhelum, Punjab, Pakistan. The present material consists of an isolated upper second premolar and a second molar of the upper left side. The presence of an advanced listriodont in Pakistan at an early stage provides valuable insights into the timing of the development of specific characteristics associated with lophodonty in Listriodontinae. Furthermore, it prompts significant
 inquiries into the early evolution of Listriodontinae in the Old World. The presence of significant physical resemblance between Listriodon guptai and Listriodon akatikubas, an African species discovered in the late early Miocene era, indicates a high likelihood that the latter species migrated from Asia. The provided specimens offer novel insights and supplementary details regarding the dental characteristics of Listriodon pentapotamiae, a species found in the Lower to Middle Siwaliks of Pakistan.

Landslide Susceptibility Assessment in Nepal’s Chure Region: A Geospatial Analysis

The Chure Hills, already vulnerable due to their fragile nature, face increased landslide risk, prompting the need for reliable susceptibility assessment. This study uses Poisson regression modeling to assess landslide susceptibility in two highly susceptible districts of the Chure region. Variance inflation factor (VIF) tests were conducted to ensure robustness, indicating no multicollinearity among the variables. Subsequently, Poisson regression analysis identified eight significant variables, among which geology, lineament density, elevation, relief, slope, rainfall, solar radiance, and land cover types emerged as important factors associated with landslide count. The analysis revealed that higher lineament density and slope were associated with lower landslide counts, indicating potential stabilizing geological and topographical influences. The categorical variable, namely geology, revealed that middle Siwalik, upper Siwalik, and quaternary geological formations were associated with lower landslide counts than lower Siwalik. Land cover types, including areas under forest, shrubland, grassland, agricultural land, water bodies, and bare ground, had a substantial significant positive association with landslide count. The generated susceptibility map that exhibited a substantial portion (23.32% in Dang and 5.22% in Surkhet) of the study area fell within the very-high-susceptibility categories, indicating pronounced landslide susceptibility in the Dang and Surkhet districts of the Chure hills. This study offers valuable insights into landslide vulnerability in the Chure region, serving as a foundation for informed decision-making, disaster risk reduction strategies, and sustainable land-use and developmental policy planning.

New remains of Dinocrocuta (Percrocutidae; Carnivora) from Markhal, Dhok Pathan Formation, Pakistan

ABSTRACT This paper describes a well-preserved left mandible of Dinocrocuta from a new fossil locality of Markhal area, Dhok Pathan Formation (Middle Siwaliks), Pakistan. The morphometric analysis of the studied materials with already known species of family Percrocutidae allows to attribute this specimen to Dinocrocuta grandis. The representation of this species exists in literature based on the already described materials, but it is the first description based on new fossil materials from the Siwaliks. In this regard, the discovery of a new material from the study area is important to resolve the generic attribution, stratigraphic range as well as the diversification of percrocutids in the Dhok Pathan Formation of the Siwaliks. Description of a new and rare fossil material from the Siwalik continental deposits is thus important to provide more information on percrocutids and to discuss its relationships with other species of genus Dinocrocuta, family Percrocutidae.

26Al and 10Be concentrations from alluvial drill cores across the Indo-Gangetic plain reveal multimillion-year sediment-transport lag times

Sediment burial can lead to significant lag times during sediment transport and is an important component of the sediment cycle. The Indo-Gangetic Plain (IGP) is a large sediment conveyer belt and understanding sediment lag times on various time scales is important for short- and long-term sediment transport and denudation-rate estimations. In this study, we have quantified the transport lag time in terms of burial duration with 14 different alluvial drill cores from 4 major Himalayan river basins, including the Ghaggar, Paleo-Yamuna, Ganges, and Kosi rivers. We rely on 56 samples using the paired cosmogenic radionuclides, 26Al and 10Be. The coring locations of paleo-Yamuna and Kosi, along with one of the Ghaggar cores are within ∼100 km from the mountain front, while the Ganges cores are ∼350 km away. The coring locations cover an E-W distance of ∼1200 km on the IGP and the depositional ages range from ∼120 kyr BP to the present day based on previous age estimations. Out of 56 samples, 39 samples show a burial signal ranging from 0.61±0.33 Myr to 3.75±1.9 Myr, with outlier values as large as ∼6 Myr.We show that the Kosi samples due to their proximity to the mountain front show no burial or a lower mean burial duration of ∼1.01 Myr, compared to the samples from the coring locations well within the IGP, such as the Ghaggar (∼2.48 Myr) and the Ganges (∼2.36 Myr). However, despite its proximity to the mountain front, the paleo-Yamuna samples have a mean burial duration of ∼2.20 Myr. Along with the floodplains and megafan surface of the IGP, we identify two potential major sediment-lag sources in the Himalayan catchment: The high and low elevation broad valleys and the Siwaliks. Increased storage spaces in the valleys north of the main Himalayan crest, including drainage-captured catchments are likely to provide long burial durations such as in the case of the Kosi and Ghaggar basins. The upper and middle Siwaliks with burial duration in the range of up to ∼6 Myr constitute a second source. We attribute the no-burial signals of 7 samples of the Kosi basin to rapid sediment generation and transportation, driven by dynamic hillslope erosion and fluvial dynamics.Importantly, our data suggest that even samples close to the mountain front exhibit million years of burial duration. These findings suggest that denudation rates derived from modern river sands or in paleo settings will need to account for burial duration and associated processes.

Fossil Species of Lagerstroemia and Millettia from Miocene Strata of the Sarkaghat Region in the Sub-Himalayan Zone of Himachal Pradesh, India, and their Palaeobotanical Inferences

Palaeobotanical investigations were conducted on plant macrofossils obtained from the Middle Siwalik sediments of Sarkaghat, Mandi District, Himachal Pradesh, India as part of this current communication. This study discovered the existence of two previously unknownfossil species that correspond to the taxa that are now living, Lagerstroemia Linn. and Millettia Wight & Arn. of the families Lythraceae and Fabaceae, respectively. These modern comparable taxa of the macrofossils reported here are distributed in the tropical evergreen tomoist deciduous forests of the south-east Asian region which may suggest that tropical forests under moist conditions were prevalent during the Upper Miocene times in this region in contrast to mixed deciduous forest under the reduced precipitation at present. It alsoindicates the prevalence of a humid tropical climate during the Miocene in the Sarkaghat area.

Mio‐Pliocene exhumation of the hinterland and sediments provenance of the Neogene strata from Kumaun Himalaya of northwest India: Insights from detrital fission‐track thermochronology

Fission‐track (FT) thermochronological analysis of detrital apatite and zircon derived from the lower and middle Siwalik Group of the sub‐Himalaya allows the reconstruction of the long‐term exhumation history of the Higher Himalayan Crystalline (HHC) and Lesser Himalayan Sequence (LHS), and also the provenance of the Siwalik sediments. Here, we report 14 detrital apatite and zircon fission‐track (AFT/ZFT) ages of lower and middle Siwalik subgroups of the Kumaun region, northwest Himalaya. Detrital FT ages suggest that all sandstone samples were never buried below the temperature range of 90° to 100°C and remained as unreset to retain a signal of source‐area exhumation. A detrital AFT age from sandstone sample at close proximity to the Main Boundary Thrust (MBT) is 4.4 ± 0.5 Ma (Pliocene time) which is completely reset and younger than the depositional age, while the detrital ZFT ages of the same sample are unrest. The AFT age represents the time of reactivation of the MBT during which ZFT ages were not affected. This study revealed that the provenances of Siwalik sediments are located majorly in the MBT hinterland areas and the nearest sources are Amritpur granite, the outer Lesser Himalayan meta‐sedimentary (LHMS) zone, Almora klippe, Ramgarh thrust sheet, and the overlying Tethyan Himalayan Sequence. These source areas can be attributed to the development of local drainage networks in the Ramganga‐Kosi drainage basin during late Miocene to Pliocene (i.e., ~9 to 4 Ma). Based on detrital FT datasets, it has been envisaged that different tectonic activities in the MBT hinterland area between Miocene and Pliocene Periods cause the tectonic upliftment and exhumation of source areas and supply the sediment to the Siwalik foreland basin.

Facies and genetic elements within the Late Miocene Middle Siwalik of the Himalayan foreland basin, India: A response of fan-building processes

The Himalayan foreland basin originated through the India–Asia continent–continent collision driven by downward flexing of the Indian plate. It forms an ideal assemblage to delineate the role of process-controlled sedimentary fill in basin evolution. This paper provides the first comprehensive account of the lithofacies associations and architecture of the Middle Siwalik succession of the Himalayan foreland basin in the south-central Himachal Pradesh sector, India through detailed sedimentological analysis. Eight lithofacies form three distinct sand, gravel, and silt-mudstone lithofacies associations pertaining to specific depositional environments. Architectural elements have been defined together with bounding surfaces separating them.Sedimentological investigations reveal that the Middle Siwalik sequence represents a flash flood dominated piedmont fan and proximal to middle megafan. The fan expansion cycles indicate tectono-climatically controlled sedimentation in the Middle Siwalik foreland basin. Frequent flooding and a high sedimentation rate were influenced by the tectonic uplift along the reactivated thrusts in the hinterland coupled with phases of monsoonal intensification.