A part of the compressed tree fern axis with leaf and adventitious root scars in unusual arrangement from Plio–Pleistocene sediments of Arunachal Pradesh, India is described as Cyathea siwalika sp. nov. This record suggests that Cyathea was an important component of tropical evergreen forest in the area during the Plio–Pleistocene and this group subsequently declined in importance within the local vegetation. © Indian Academy of Sciences.

SUBIR BERA

Botany

S GUPTA

KHAN M ALI

A DE

R MUKHOPADHYAY

Fulltext

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Journal of Earth System Science

Here, we report fossil leaves, woods, and pollen grains comparable to Calophyllum L. (mainly to Calophyllum inophyllum L. and Calophyllum polyanthum Wall. ex Choisy) of Calophyllaceae from the upper (Kimin Formation, late Pliocene-early Pleistocene), middle (Subansiri Formation, Pliocene) Siwalik sediments of the Arunachal sub-Himalaya, and lower (Gish Clay Formation of Sevok Group; middle to late Miocene) Siwalik sediments of the Darjeeling foothills, eastern Himalaya. Their presence indicates a warm and humid tropical environment in the region during the period of Siwalik sedimentation. Considering all records of Calophyllum, it is suggested that Calophyllum was a frequent forest element throughout the period of Siwalik sedimentation during the Neogene (Miocene time). At present, C. polyanthum grows in the eastern Himalaya, but C. inophyllum is totally absent from north-eastern regions suggesting differential adaptability of these taxa to changing ecoclimatic conditions. Distinct climate change in the area, possibly related to the Himalayan Orogeny during Miocene–Pleistocene times, might have caused the disappearance of C. inophyllum from the entire eastern Himalaya and north-east Indian plains and a move to littoral/coastal and swampy forests of India and other adjoining south-east Asian regions, Polynesia, and the east coast of Africa. The past global distribution of Calophyllum is also discussed, and it is suggested that India may have been its primary centre of origin. This is the first time Cenozoic fossil leaves Calophyllum siwalikum Khan, R.A.Spicer & Bera, sp. nov. comparable to C. inophyllum are described using the both macro- and micromorphological characters. © 2017, Springer-Verlag Wien.

Plant Systematics and Evolution

Evidence for diversification of Calophyllum L. (Calophyllaceae) in the Neogene Siwalik forests of eastern Himalaya

Four legume fruits (Fabaceae) from the Siwalik sediments (middle Miocene to lower Pleistocene) of Darjeeling and Arunachal Pradesh of Eastern Himalaya are described here. One fossil fruit, Dalbergia prelatifolia sp. nov., is recovered from the lower part of the Siwalik succession (Gish Clay Formation of Sevok Group; middle to upper Miocene) of Darjeeling foothills. Mastertia neoassamica sp. nov. and Acacia miocatechuoides sp. nov. are collected from the lower part of the Siwalik succession (Dafla Formation; middle Miocene to upper Miocene), while Pongamia kathgodamensis Prasad is recovered from the upper part of the Siwalik succession (Kimin Formation; upper Pliocenelower Pleistocene) of Arunachal sub Himalaya. Their presence indicates a warm and humid tropical environment in the region during the Siwalik sedimentation. © 2014 Geological Society of India.

Journal of the Geological Society of India

On some fabaceous fruits from the Siwalik sediments (Middle Miocene-Lower Pleistocene) of Eastern Himalaya

Four fossil floras ranging in age from the mid Miocene to the early Pleistocene from the eastern Siwaliks near Darjeeling and in Arunachal Pradesh (AP) were compared taxonomically and subjected to a CLAMP (Climate Leaf Analysis Multivariate Program) analysis using a new calibration dataset that includes sites from India, southern China and Thailand and high resolution gridded climate data. Two lower Siwalik mid Miocene floras yielded almost the same values suggesting mean annual temperatures (MATs) of 25.4 and 25.3 °C ± 2.8 °C (all uncertainties ± 2 sigma) with warm month mean temperatures (WMMTs) of 28.4 and 27.8 ± 3.39 °C and cold month mean temperatures (CMMTs) of 17.9 and 21.3 ± 4 °C. Precipitation estimates have high uncertainties but suggest a weak monsoon with growing season precipitations of 242 ± 92 cm for Darjeeling and 174 ± 92 cm for AP. Leaves from the middle Siwalik (Pliocene) sediments of AP indicate a lowering of the MAT to 23.7. °C, a function of cooler winter months (CMMT 16.9. °C). The AP early Pleistocene temperatures and rainfall were similar to those of the mid Miocene. Changes in the monsoon index suggest that in the AP area there has been little change in the intensity of the monsoon since mid Miocene time, while further west at Darjeeling there has been an intensification since the mid Miocene. Mid Miocene CLAMP-derived enthalpy estimates provide sea level (< 200 a.m.s.l) data for a re-evaluation of the palaeoelevation of a 15. Ma flora from the Namling-Oiyug Basin, southern Tibet. Enthalpy values from Darjeeling and AP were 354.1 and 355.8 ± 10.3 kJ/kg respectively, while that derived from the Namling-Oiyug flora was 296.3. kJ/kg. This yields a palaeoelevation of 5888. m for the Namling site using the Darjeeling enthalpy estimate as a sea level datum and 6065. m using the AP assemblage. The combined uncertainty is ± 728 m. Model corrected enthalpy trends at sea level across palaeolatitude and longitude reduce the mean elevation to 5.54. km. These elevations are higher than earlier estimates from the same site (but within uncertainty) and the corrected mean is ~. 1. km higher than the present day basin floor elevation in the region, suggesting some deflation since 15. Ma associated with east-west extension, particularly if a shift in the locus of deformation and uplift south to the Himalayas in post middle Miocene times relieved N-S compressional stress on southern Tibet. © 2013 Elsevier B.V.

Global and Planetary Change

Miocene to Pleistocene floras and climate of the Eastern Himalayan Siwaliks, and new palaeoelevation estimates for the Namling-Oiyug Basin, Tibet

Leaf remains of 4 lauraceous taxa collected from the Siwalik sediments (Middle Miocene to Pliocene) of Arunachal Pradesh of eastern Himalaya are described in the present communication. One fossil leaf, Cinnamomum palaeobejolghota sp. nov., was recovered from the lower part of the Siwalik succession (Dafa Formation; Middle to Upper Miocene), while Persea mioparviflora sp. nov., Persea preglaucescens sp. nov., and Lindera neobifaria sp. nov. were collected from the middle part of the Siwalik succession (Subansiri Formation; Pliocene) of Arunachal sub-Himalaya. Te geographic distribution of the fossils and their modern counterparts is discussed and on that basis tropical vegetation under warm and humid climate during deposition of the Siwalik sediments is suggested. Te present study also suggests probable migration of these lauraceous taxa in South-East Asia. © TÜBİTAK.

Turkish Journal of Botany

New lauraceous species from the Siwalik forest of Arunachal Pradesh, eastern Himalaya, and their palaeoclimatic and palaeogeographic implications

A morpho-taxonomic study of leaf remains from the upper part of the Siwalik succession of sediments (Kimin Formation; upper Pliocene to lower Pleistocene) of Papumpare district, Arunachal Pradesh, India, revealed 23 species representing 20 genera belonging to 15 angiosperm families. The recovered fossil leaves are comparable to modern Bambusa tulda Roxb. (Poaceae), Mangifera indica Linn., Dracontomelum mangiferum Blume (Anacardiaceae); Chonemorpha macrophylla G. Don (Apocynaceae); Pongamia pinnata (L) Pierre., Millettia pachycarpa Benth., Dalbergia rimosa Roxb., Millettia extensa (Fabaceae); Macaranga denticulata Muell. Arg., Croton caudatus Geisel. (Euphorbiaceae); Combretum decandrum Roxb. (Combretaceae); Dysoxylum procerum Hiern. (Meliaceae); Dipterocarpus sp. Gaertn.f. (Dipterocarpaceae); Actinodaphne angustifolia Nees., Actinodaphne obovata Blume., Lindera pulcherrima Benth., Litsea salicifolia Roxb. (Lauraceae); Calophyllum polyanthum Wall. (Clusiaceae); Knema glaucescens Hook.f. (Myristaceae); Canarium bengalense Roxb. (Burseraceae); Quercus lamellosa Smith; Quercus semicarpifolia Smith (Fagaceae); and Berchemia floribunda Wall. (Rhamnaceae). Among these taxa, 11 species are recorded as new to the Neogene flora of India. Analysis of the floral assemblage with respect to the distribution pattern of modern equivalent taxa and the physiognomic characters of the fossil leaves, suggests that a tropical evergreen forest was growing in a warm humid climate in the region at the time of deposition. This is in contrast to modern tropical semi-evergreen forests that occupy the area. Values of mean annual temperature (MAT) of 29.3°C and mean annual precipitation (MAP) of 290 mm have been calculated using leaf-margin characters and fossil leaf size. © Senckenberg Gesellschaft für Naturforschung and Springer 2011.

Journal	Journal of Earth System Science
Publisher	Indian Academy of Sciences
ISSN	0253-4126
Open Access	No