bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quaternary Palaeobotany/Palynology in the Himalaya an overview
Authors: Vishnu-Mittre  
Published: September 2022

The overview appraises critically the work on Quaternary palaeobotany/palynology carried out in the Himalayas during the last hundred years. The fluctuations in cool and temperate vegetation and climate during the early Quaternary (Lower Karewas), aspects of vegetational development during the last glacial and during the present inter-glacial period impart a glimpse of the changing patterns of vegetation through the Quaternary period. Further, it urges the construction of more pollen diagrams, intensification of research on the comparative database together with increased indigenous ecological insight and the sophistication in methodology to bring out invaluable information of biogeographical, geological and archaeological interests. The history of lake basins and fluctuations in hydrochemistry should be built up through the studies of diatoms in conjunction with pollen and spores.
The studies of the evolution of Quaternary floristics should not overlook the historical perspective, i.e, its evolution from the Miocene/Pliocene flora. The recognition of the transitional stage in the evolution of flora is highly imperative to demarcate the Neogene/Quaternary boundary on botanical grounds. A few names for various stages (vegetational/climatic phases) during the Quaternary have been proposed after the type sites in keeping with the Code of Stratigraphical Nomenclature for their use in bio-and chronostratigraphy. Besides, it emphasises the importance of indigenous ecological insight in solving the ecological problems and biogeographical riddles in the diversity of floristics in the Himalayas and determines the rate and extent to which the forests in the Himalayas have been adversely affected by the progressive increase in land use and by the progressive and selective exploitation of the forest constituents.
The fossil floras of Kachchh. III - Tertiary megafossils
Authors: Lakhanpal R.N. , Guleria J.S. , Awasthi N. 
Published: September 2022

A complete account of plant megafossils described so far from the Eocene, Miocene and Pliocene beds of Kachchh District has been given. The megafossils belong to Algae and Phanerogams. The algal remains comprise the calcareous red algae assigned to the family Corallinaceae. Out of eight species belonging to five genera, three species representing the two genera: Lithothamnium and Lithophyllum, have been reported from the Eocene and five species belonging to the genera Lithophyllum, Mesophyllum, Archaeoporolithon and Aethesolithon are from the Lower Miocene deposits. The phanerogamous megafossils have been described from the Lower Eocene, Miocene and Pliocene beds. The Eocene megafossils consist of leaf-impressions belonging to eight species of dicotyledons and one species of monocotyledons. The Miocene assemblage is based on leaf impressions, seeds and petrified woods assigned to 14 genera and 15 species of dicotyledons and a palm. The megafossils recovered from the Pliocene deposits are all petrified woods belonging to seven families (5 dicotyledons, 1 palm and I gymnosperm) represented by 14 genera. Besides, two palm woods and a graminaceous stem reported from unknown Tertiary horizons have also been included.
In the light of distribution of their modern comparable forms, all the components of the Tertiary flora of Kachchh are tropical. Because of the occurrence of moist evergreen as well as deciduous taxa, the flora can be placed under the category of "moist tropical semi-evergreen to deciduous forests". The environment of deposition seems to have been mainly lacustrine and fluviatile. The overall vegetation of Kachchh during the Tertiary period was more luxuriant than the scrubby vegetation thriving there today. Obviously the present xeric conditions are a result of post-Pliocene changes in the climate in this area. Even during the Tertiary, Kachchh witnessed periodic changes in climate. It was moist during the early Eocene, gradually becoming comparatively drier during early Miocene and again turning moist towards the end of Miocene.
The occurrence of marine algae in the Eocene and Miocene deposits indicates that there was transgression of sea in Kachchh during Eocene and Miocene epochs.
Revision and reasseessment of a dinoflagellate cyst assemblage from Sangchamalla Formation (Upper Flysch), Malla Johar area, Kumaon Himalaya, India
Authors: Jain K.P. , Garg Rahul 
Published: September 2022

A dinoflagellate cyst assemblage described by Mehrotra and Sinha (1981) from Sangchamalla Formation (Upper Flysch) of Malla Johar area in the Tethyan zone of higher Kumaon Himalaya is critically re-evaluated.
The taxonomic revision of the assemblage on its face value indicates total absence of Areosphaeridium diktyoplokus (Klumpp) Eaton, A. arcuatum Eaton, Homotryblium tenuispinosum Davey & Williams, Hystrichokolpoma unispinum Williams & Downie, Diphyes colligerum (Deflandre & Cookson) Davey & Williams and Deflandrea speciosa Alberti based on which a Lower Tertiary age was assigned by Mehrotra and Sinha (1981). Instead, it is characterized by the predominance of Oligosphaeridium with the common occurrence of Coronifera, Gonyaulacysta, Hystrichosphaerina, Tityrosphaeridium and Cordosphaeridium. A new species, viz., Hystrichospheridium himalayaensis proposed by Mehrotra and Sinha (1981) is treated as a junior synonym of Oligosphaeridium complex (White) Daey & Williams.
The revised dinocysts assemblage is devoid of exclusive Tertiary taxa and indicates an Upper Cretaceous age. The possibility of Lower Cretaceous reworking in the ‘Upper Flysch’ assemblage is suggested. The occurrence of dinocysts in the deep oceanic environment of the ‘Upper Flysch' sediments is considered to be most probably due to transportation from shallower regions through sedimentary processes.
Kamthi - a new concept
Authors: Pande B.C. 
Published: September 2022

King has described ‘Kamthi beds’ as the group of rocks disconformably overlapping the Permian coal measures. In an otherwise extremely soil covered areas in the Wardha Godavari Graben. Some of the later workers while projecting on the surface the lithics encountered in the sub-surface drilling in the Godavari Valley Coalfield subdivided these beds into lower, middle and upper horizons, by considering them to have gradational contacts, to account for the biota revealed from these litho-units.
A reappraisal of the basic geoscientific database (geological and geophysical) and the interpretations from the surface and the sub-surface lithics have undisputedly shown that the pattern of Gondwana sedimentation in the Godavari Valley, during the Palaeozoic and Mesozoic periods, has been in an oscillating and continental fluvial regime governed by the basin configuration and palaeodrainage interrelated to their development in time and space.
The palynofossil content unequivocally proves the presence of the Upper Permian lithics lying buried under the Lower Triassic (Kamthi) sediments. The latter has a widespread expanse in the graben, from the northwest to the southeast which is believed to be due to the further deepening of the basin floor at the time of their sedimentation.
The possibility of Kamthi constituting the basal part of the enlarged Maleri sequence of the Triassic lithics is very much indicated thereby defining the base of the Triassic in the Godavari Graben. It is thus, considered undisputed that the Kamthi is nothing more than a concept in the geological history of this part of the Godavari Graben which is defined by its mode of occurrence as governed by the associated tectonism.
The Origin, rise and decline of Glossopteris Flora: with notes on its palaeogeographical northern boundary and age
Authors: Pant D.D. 
Published: September 2022

In Africa impressions of two leaves of Gangamopteris were found below the glacial conglomerate and in Australia Gangamopteris and Schizoneura were found interbedded with the glacial beds at Bacchus Marsh. Microfossils, including pollen grains like those of the Glossopteris Flora, have been reported from the tillites, particularly from the Bacchus Marsh tillite. Similar microfossils have also been reported from the beds of the Talcher stage lying immediately above the glacial beds. All these fossils indicate that they were the pioneers of the Glossopteris flora which may have come into existence in unglaciated and protected locations of Gondwanaland during the Ice Age itself. The early elements of the Glossopteris Flora thus seem to have lived in a cold temperate climate alongside glaciers. The flora of this stage was relatively poor but as the climate warmed up the forests became richer and their plants more diversified. However, this flora was living in a climate where a cold winter alternated with a warm summer and it abounded in deciduous plants. The climax of the Gondwana vegetation was reached during the Raniganj stage when a much warmer and more humid climate supported a rich forest vegetation again abounding in deciduous trees. Thereafter, there was a sudden change of vegetation during the Triassic when the plants of the Glossopteris Flora yielded place to new elements of the Dicroidium Flora.
The disappearance of the Rhacopteris-Lepidodendropsis Flora with the onset of the glaciation during the Carboniferous-Permian times is easily understood but the sudden appearance of an entirely new Glossopteris Flora after, or even during the glaciation itself, and its almost simultaneous spread in all parts of Gondwanaland raise difficult questions about its origin and phylogeny. Besides dealing with the answers to these questions, the author discusses the factors and implications of the gradual decline of the Glossopteris Flora and the rise of the Dicroidium Flora during the Triassic. The estimates of the geological age and palaeogeographical limits of the Glossopteris Flora are also scrutinized in the light of recent work.
Northern limits of the eastern Gondwana: palaeobotanical evidence
Authors: Maheshwari H.K. , Bajpai Usha 
Published: September 2022

The northern margin of the Gondwanaland along the Indian block has been debated for some time now. According to the earlier view the northern margin ran along the Indus-Yarlung-Zangbo Suture. Newly acquired data has been interpreted to show that eastern Gondwana was much bigger than generally believed.
In the present work we analyze the floras that grew around the northern margin of the eastern Gondwana assembly to see if the distribution of plant fossils also provides supporting evidence for a ‘greater’ India. The floras that have been examined in the present synthesis originate in the Permian of New Guinea, Sumatra (Indonesia), Malaysia, Thailand, Tibet, Northern China, Kashmir (India), Saudi Arabia, Iran, Iraq and Turkey and Mesozoic of Ladakh (India), Bhutan and Nepal.
The analysis shows that though some of the floral assemblages contain certain elements that could be of Gondwana affinity yet the overall composition of almost all the floral assemblages, except the one from Kashmir, is basically Cathaysian. Whether these Cathaysian type floral assemblages occupied the northern margin of the eastern Gondwana or they flourished on the southern margin of Laurasia, or they grew all along the shores of the Tethys, has to be examined.
The latitudinal variation in vegetation, however, does not seem to explain the intermixing of elements of different floral provinces in the coastal vegetation on the two shores of a fairly wide, though shallow, Tethys as in Kashmir and in southern Tibet. Even if both these regions were on the same side of Tethys, intermixing of Gondwana and Cathaysia floras is not explained as no direct migratory routes from Laurasia are available in Gondwana assemblies.
This coupled with the occurrence of northern Mesozoic flora at Fukche, Ladakh, and near Lhasa indicates that the Indian Gondwana did not extend north of the Indus-Yarlung-Zangbo Suture Zone.
Morphology of Bennettitalean fructifications
Authors: Sharma B.D. 
Published: September 2022

The Bennettitales dominated the vegetation throughout the world during Mesozoic Era. In external morphology they were cycad-like, but had distinct type of fertile parts. Fructifications were monosporangiate or bisporangiate. In seed-bearing fructifications a compact layer of fertile and sterile scales surrounded the conical/hemispherical receptacle. On the basis of ontogeny and anatomy, both types of scales are described as appendicular structures and derived the fructification from Cordaianthus. Bisexual fructifications resemble cycadeoideas. Male fructifications are unique and can be correlated neither with any known extinct nor extant plant. Bennettitales originated independently from protoseminales, a plexus which also gave rise to cordaitales and pteridosperms, Bennettitales ended abruptly.
Temporal and spatial variations of the type and rank of Gondwana coals of India
Authors: Navale G.K.B. 
Published: September 2022

Gondwana coals associated with Permian sediments in peninsular India vary widely but there is a distinct tendency of variation to be diagnostic both in time and space. The three maceral groups (Vitrinite, Liptinite and Inertinite) which are derived from diversified plant material exist in the Gondwana coals. However, maceral composition is controlled by the type of plant material available for accumulation as peat and by Eh and pH of the ancient swamp. These may all be in part controlled by the period when the peat was formed, climate and sedimentary environment. These variables seem to be inter-related rather than independent. The coals that occur in Karharbari, Barakar and Raniganj formations differ significantly in their nature and relative distribution of coal constituents.
The coals, deposited under wide range of tectonosedimentary settings of Permian Gondwana sequence, reveal fusic, trimaceric and vitric coal types and by and large associated with different lithologic sequences in ascending order. Provincialism can be discerned both in relation to lateral variation of individual seams and in differences between the modal composition found in different coal measures. Significant variation occurs within the individual seams, however, they retain some degree of characteristic petrological identity. Different seams in a given stratigraphic unit may differ widely in their petrographic composition but are characterized by their diagnostic modal composition. The coals of Damodar, Son-Mahanadi, Pench-Kanhan and Wardha-Godavari basins provide good examples for the temporal and spatial variation of the coal seams.
Coal rank assessed has shown significant variation in rank both in space and time ranging from high volatile sub-bituminous to low volatile bituminous stages including coking coal types. The wide range of coal rank recognized in the Gondwana of India is controlled by geothermal gradients and tectonic features. These have affected the extent of coalification by controlling the heat flow to which coals have been exposed. Tectonism may also have exercised some control over coal types (rank types) but only as a part of a complex mechanism which also involved sedimentary environment, the climate and the flora at any given time.
Phloem in Pinophyta
Authors: Paliwal G.S. 
Published: September 2022

The gymnospermous phloem shows major differences from those of the cryptogams on one hand and the angiosperms on the other. These include both the type of conducting cells as well as the cellular composition. Even more important is the degree and nature of functional inter-relationship between the conducting and parenchyma cells. The following evolutionary trends have been suggested.
Increase in the amount of axial parenchyma;
Decrease in the number of albuminous cells in the rays;
Increase in the axial albuminous cells;
Increase in the fibres;
Increase in the regular arrangement of cells.
The work on the fossil taxa does provide variable support to these suggestions. It is generally believed that the cryptogamic sieve element arose from a parenchyma cell and all the phloem produced in the fossil lycopods, Sphenopsida and ferns is primary in origin. Here the phloem consists of either sieve elements only or the sieve elements with scattered parenchyma cells. There is no definite relationship between the conducting elements and the parenchyma cells as seen in the seed plants. Additional parenchyma is often present in the form of a sheath separating the xylem from the narrow phloem tissue.
The typical cryptogamic sieve elements are identical to the elongate parenchyma cells. These are relatively small in diameter, longer than the parenchyma cells but shorter than the gymnospermous sieve cells. In some taxa, the sieve elements are of two sizes: large (up to 600µm) and small (between 100-1500 µm). The end walls of the cryptogamous sieve elements are horizontal or slightly oblique and the sieve areas are small and vary markedly in their outline. The sieve pores occur in the sieve areas as well as scattered on the vertical walls. The callose deposition has been found in Psilotum, lycopods and the ferns.
Trends in the evolution of the angiosperm flowers
Authors: Rao R.R. 
Published: September 2022

The flower is classically defined as a determinate shoot that bears modified leaves. It is believed that the primitive flowers are those which possess numerous floral parts, all spirally arranged on the floral axis. Discussing the origin of the flowers it is claimed that the flowering plants might have evolved from the hypothetical ‘Proangiosperms’ that existed in the Late Mesozoic Era and had characters of both gymnosperms and angiosperms. Among other factors, seasonal climate is believed to have caused the angiospermatization in the early proangisperms.
Primitive flowers, such as those of Magnoliales, are all solitary, regular and moderately sized in which the floral parts are all separate and indefinite in number. It is stressed that the evolution of the flower is guided by (a) principle of progressive economy in the production of floral parts, and (b) principle of progressive adaptation to insect visitors. Adaptations of angiosperms to insect visitors include development of conspicuous flowers (either by enlargement of individual flowers or by aggregation of separate flowers), development of zygomorphy and fusion of floral parts. Primitive flowers lack a differentiation between calyx and corolla. Derived perianth features are said to include (a) evolution of two distinct whorls of perianth-calyx and corolla, (b) establishment of a regular number of floral parts, (c) fusion of sepals and petals, and (d) development of zygomorphy.
Primitive stamens, characteristics of the genus Degeneria (Degeneriaceae: Magnoliidae) are broad and laminar and evolution proceeded towards transformation of such laminar stamens to a distinct filament and anther. Tendency towards reduction in the number of stamens is also quite evident. Similarly the flowers with many free carpels (as in Magnoliales) have given rise to flowers with syncarpous gynoecia which have further evolved to give rise to inferior ovary by the fusion of gynoecial walls to the calyx and receptacle.
Finally it is said that the above evolutionary modifications in the flowers/flower parts are fundamentally guided by the mode of pollination and pollination mechanism and have been attempted independently by different groups of plants- a fact that suggests the polyphyletic nature of angiosperms.
Dinocyst biostratigraphy of Santonian-Maastrichtian formations of the Western Gulf Coastal Plain, southern United States
Authors: Srivastava Satish K. 
Published: September 2022

This palynological investigation of Santonian-Maastrichtian formations of Texas, U.S.A. consists of an examination of 82 outcrop samples from 19 stratigraphic sections exposed in 9 countries in a north-south trend from about Dallas to Kinney. The Austin Chalk Formation, the Taylor Group, and the lower Navarro Group are examined for palynological data. Most of the samples are rich in dinocysts assemblages. In a total assemblage of 163 palynomorphs species in 95 genera, 111 dinocyst species of 60 genera, 6 acritarch species of 5 genera, and 46 spore pollen species of 33 genera are recognized and their stratigraphic distribution documented. Systematic descriptions and illustrations of all dinocysts and acritarch taxa are given. Spore-pollen taxa occur sporadically in the studied sections and thus are only listed, illustrated and their occurrences noted in the text.
The stratigraphic distribution of dinocysts species indicating the Santonian age can be recognized by the presence of Chatangiella granulifera, C. robusta, C. spectabilis, Phelodinium gaduatum and Spinidinium lanturnum. The characteristic species of Campanian assemblage are Cannosphaeropsis hyperacantha, C. utinensis, Ceratiopsis subquadra, Chattangiella armata, C. williamsii, Diconodinium martianum, Dinogymnium denticulatum, D. enclaense, D. nelsonense, Impagidinium cristatum, I. microarmum, Rottnestia borusstca, Triblastula utinensis and Xenascus gochtii.
The appearance of the following dinocysts species viz., Andalusiella acicornula, Areoligera senonensis, Ceratiopsis navarriana, Glaphyrocysta retiintexia, Lejeunecysta decorinassa, L. byalina, Litosphaeridium fenestreconum, Palaeocystodinium australinum, Phelodinium tricuspe and Thalassiphora bononiensis in the Maastrichtian is significant.
Pollen occurrences indicate that the land area, west of the Senonian epeiric sea, was terrigenous source in the Santonian and the Late Maastrichtian whereas the land on the east of the eperic sea was the source in the Campanian.
Differential morphographic identity of Gondwanic palynomorphs
Authors: Tiwari R.S. , Vijaya  
Published: September 2022

The exine structures, bauplan and germinal apertures are the basic characters for the morphographic of fossil spores and pollen. The apparent but unreal form-similarities of some bisaccate pollen taxa or Sporae dispersae from Gondwanaland on one hand and those in the contemporary Euromerian sequences on the other, have been sorted out in this paper. Trends of different exine structures and saccus organization have been identified in pollen. This concept has been exemplified by the fact that the pollen taxa Lunatisporites, Lueckisporites and Klausipollenites of the north possess mostly imperfect reticulate, compactly placed grana, columnar elements, rodlets, vermiculale, verrucae or similar elements mixed together, rounded or multifaceted islands of various shapes and sizes, incomplete or even isolated closely packed muri as exinal elements which make the infra-structure of the sexine in the corpus. In contrast to this trend, the major pattern of exine structure in apparently similar taxa of the Gondwanaland is different; most of the pollen groups exhibit perfectly infrareticulate structure on corpus with complete muri and distinct meshes.
Such a differential morphographic identity may lead to a more rational model of the palaeo-phytogeography based on palynofossils, because the genuine similarities and differences could be effectively used in delimiting the floral provinces. The distinctions in the mother vegetations, which have had produced pollen and spores in two region, corroborate the distinctions in the groups of palynotaxa discussed here. This paper proposes the theory of the Apparent Form Similarity (AFSIM Factor) and highlights certain lines of differentiation amongst the similar-looking but basically different spore-pollen components produced by unrelated plant groups. Some aspects of palynofloral distribution vis-à-vis climate changes through Gondwana have also been discussed.