Anju Saxena

Spondylodendron pranabii—the dominant lycopsid of the late Mississippian vegetation of the Kashmir Himalaya

Cleal, C.J., Bhat, G.M., Singh, K.J., Dar, A.M., Saxena, A. & Chandra, S., February 2016. Spondylodendron pranabii—the dominant lycopsid of the late Mississippian vegetation of the Kashmir Himalaya. Alcheringa 40, xxx–xxx. ISSN 0311-5518. The Sepukhovian fossil floras of the northern margins of Gondwana, on the shores of the Palaeotethys, are dominated by remains of an eligulate, mainly monopodial lycopsid with persistent leaves. The stems show considerable morphological and preservational variation that has historically resulted in the fossils having been assigned to many fossil-species and -genera. However, there is now clear evidence that this simply reflects variation within a single fossil-species, reflecting biological variation and the effects of variable taphonomy, for which the correct taxonomic name is Spondylodendron pranabii (Pal) comb. nov. Part of this morphological variation might have been due to variations in growth rate during the life of the individual plants, which in turn might reflect stressed growing conditions in a wetland habitat. The systematic position of Spondylodendron remains uncertain, owing to the lack of unequivocal evidence of reproductive structures, but it might have affinities with the Sublepidodendraceae. Christopher J. Cleal [chris.cleal@museumwales.ac.uk], Department of Natural Sciences, National Museum Wales, Cathays Park, Cardiff CF10 3NP, UK; G.M. Bhat [bhatgm@jugaa.com] and A.M. Dar, Department of Geology, University of Jammu, Jammu, India; Kamal Jeet Singh, [kamaljeet31@hotmail.com] and Anju Saxena [anju_saxena2002@yahoo.co.in], Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, (U.P.) India; Shaila Chandra, Flat Number 105, Beverly Park Apartment 422, New Hyderabad, Lucknow-226007, (U.P.) India.

Carboniferous floras in siliciclastic rocks of Kashmir Himalaya, India and the evolutionary history of the Tethyan Basin

The Fenestella Shale Formation of Jammu and Kashmir Himalaya comprises latest Visean or Serpukhovian siliciclastic deposits formed along the southern margins of the Palaeotethys Ocean. A sequence of shallowing upward and deepening upward units indicates changes from shoreface to offshore and deeper shelf conditions, probably controlled by eustatic changes in an otherwise passive depositional system. Some of the finer-grained, shallow marine deposits have yielded fossil floras dominated by sub-arborescent lycopsids ( Sublepidodendron , Lepidodendropsis ) sphenophytes ( Archaeocalamites ) and pteridophylls ( Nothorhacopteris , Triphyllopteris ). The assemblage compares with other Gondwanan floras of this age that have been assigned to the Paraca floral realm, and are taken to indicate relatively warm climatic conditions that existed just prior to the onset of the Carboniferous–Permian ice-age.

Spore tetrads, possible indicators of intense climatic regimes: case study from an early Permian stratum of Singrauli Coalfield, Son-Mahanadi Basin, India

A large number of naked, fossil spore tetrads assignable to the dispersed microspore genera Indotriradites, Microbaculispora and Microfoveolatispora are reported for the first time from an early Permian stratum (Lower Barakar Formation) of Singrauli Coalfield, Son-Mahanadi Basin, Central India. This is also the first record of tetrads from any Artinskian strata in the world. There is no evidence of any kind of sporangia or related plant parts in the present investigation that could ascertain the affinity of these tetrads; however, the presence of a trilete mark in the spores of the tetrads demonstrates their alliance at least with the pteridophyte group. The present study suggests possible factors affecting the sporogenesis process in the past, considering other available global records pertaining to fossil spore tetrads. The results of significant physiological and biochemical analyses performed on the anthers of modern plants related to reproductive biology, in order to understand the conditions and changes responsible for the formation of tetrads, are also considered. We analysed the globally occurring fossil tetrads and the palaeoclimates prevailing during their deposition. A correlation between extreme climatic conditions, specific pH values inside microsporangium and the formation of tetrad is envisaged. It is deduced that extreme climatic conditions (extreme cold/extreme hot) might have triggered some sort of malfunctioning in the sporogenesis process that altered the specific pH values inside the microsporangium. Any restraint of the activity of the callase enzyme, responsible for dissolution of callose walls laid between the individual spores, may therefore have apprehended the dissociation of tetrads into individual spores.

Biostratigraphy and floristic evolution of coal swamp floras of a part of Talcher Basin, India: a window on a Permian temperate ecosystem

The present megafloral assemblage recorded from the Barakar sediments of Dholpahar section along Singda rivulet near Gopal Prasad Village in Talcher Basin comprises of equisetaceous stems, Gangamopteris buriadica, Palaeovittaria kurzii and 19 species of the genus Glossopteris. Record of Gangamopteris, Palaeovittaria and many narrow mesh forms of Glosspteris viz., G. angustifolia, G. churiensis, G. communis, G. recurva, G. spatulata, G. stenoneura, G. tenuifolia, G. vulgaris and G. zeilleri from two older fossiliferous horizons demonstrates that these fossils were preserved during Lower Barakar sedimentation. The report of middle and broad mesh forms of Glossopteris viz., G. barakarensis, G. browniana, G. indica, G. intermittens, G. karharbariensis, G. nakkarea, G. oldhamii, G. taeniensis and G. retifera in the youngest fossiliferous horizons reveals that these fossils were preserved during the deposition of Upper Barakar sediments. The continuation of some of the Karharbari plant fossils in the early phase of Barakar Formation and their disappearance in the flora of Late Barakar suggests a shift in the climatic setup. Palaeoclimate and palaeovegetation of this area are also summarised in this study. Moreover, the fossil assemblages of different fossiliferous beds of Dholpahar section demonstrate the evolution of midrib and meshes in different reticulate leaves.

Permian macro- and miofloral diversity, palynodating and palaeoclimate implications deduced from the coal-bearing sequences of Singrauli coalfield, Son–Mahanadi Basin, central India

The coal-bearing sequences of Barakar and Raniganj formations exposed in Bina and Jhingurdah open-cast collieries, respectively, are analysed for their macro- and miofloral content. The sediment successions primarily comprise of sandstones, shales, claystones and coal seams. In addition to the diverse glossopterid assemblage, four palynoassemblage zones, namely Zones I and II in Bina Colliery and Zones III and IV in Jhingurdah Colliery, have also been recorded in the present study. The megafossil assemblage from the Barakar strata of Bina Colliery comprises of three genera, namely Gangamopteris, Glossopteris and cf. Noeggerathiopsis. Palynoassemblage-I is characterised by the dominance of non-striate bisaccate pollen genus Scheuringipollenites and subdominance of striate bisaccate Faunipollenites and infers these strata to be of Early Permian (Artinskian) age (Lower Barakar Formation). The palynoassemblage has also yielded a large number of naked fossil spore tetrads, which is the first record of spore tetrads from any Artinskian strata in the world and has a significant bearing on the climatic conditions. The palynoassemblage-II is characterised with the dominance of Faunipollenites over Scheuringipollenites and is indicative of Kungurian age (Upper Barakar Formation). The megafossil assemblage from the Raniganj Formation of Jhingurdah Colliery comprises of five genera with 26 species representing four orders, viz., Equisetales, Cordaitales, Cycadales and Glossopteridales. The order Glossopteridales is highly diversified with 23 taxa and the genus Glossopteris, with 22 species, dominates the flora. The mioflora of this colliery is represented by two distinct palynoassemblages. The palynoassemblage-III is correlatable with the palynoflora of Early Permian (Artinskian) Lower Barakar Formation. The assemblage suggests the continuity of older biozones into the younger ones. The palynoassemblage-IV equates the beds with composition V: Striatopodocarpites–Faunipollenites–Gondisporites assemblage zone of Tiwari and Tripathi (1992) of Late Permian (Lopingian) Raniganj Formation in Damodar Basin. The FAD’s of Alisporites, Klausipollenites, Falcisporites, Arcuatipollenites pellucidus and Playfordiaspora cancellosa palynotaxa in this assemblage enhance the end Permian level of the Jhingurdah Top seam, as these elements are the key species to mark the transition of Permian into the Lower Triassic.

Morphological and stratigraphical significance of lower Gondwana plant fossils of Mohpani Coalfield, Satpura Gondwana Basin, Madhya Pradesh

Plant fossils from the coal bearing Barakar Formation exposed in Gottitoria open cast mine of Mohpani Coalfield, Satpura Gondwana Basin are described for the first time. The assemblage is represented by Glossopteris communis, G. indica, G. stenoneura, Gangamopteris angustifolia, G. cyclopteroides, G. karharbariensis, G. major, seeds of Cordaicarpus zeilleri and equisetaceous stems. The dominance of the species of Gangamopteris over the species of Glossopteris and absence of Noeggerathiopsis indicate the floral affinity with the flora of Lower Barakar Formation of Lower Gondwana.