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  • Articles  (147)
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  • 1
    Publication Date: 2019-12-01
    Description: Attempts at reconstructing palaeoclimatic changes over time using palynomorphs of three oil wells drilled in the shallow offshore Niger Delta led to cluster analysis-aided recognition of seven pollen zones. These pollen zones are equivalent to ten palaeoclimatic zones with alternating dry and wet conditions. The palynomorphs were classified into phytoecological groups and changes in their relative abundances were employed to interpret the palaeoclimatic conditions of their source areas. Contrasting fluctuations in the proportions of the Spore (Pteridophytes) phytoecological group and those of the Poaceae were the main basis for palaeoclimatic inferences. Trends of the occurrence of other phytoecological groups were used to substantiate our palaeoclimatic inferences. In the latest Miocene (5.8–5.5 Ma), climatic conditions were mainly wet until between 5.5 and 5.0 Ma, when extreme dry conditions prevailed. The early Pliocene part (5.0–〉3.4 Ma) was generally wet, while the late Pliocene part (
    Print ISSN: 0001-6594
    Electronic ISSN: 2082-0259
    Topics: Biology , Geosciences
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  • 2
    Publication Date: 2019-12-01
    Description: The paper reports a palaeoxylotomical study of petrified palm remains (stem, root, rachis) collected from some fossil sites of Greece (Evros, Lemnos, Lesbos and Kastoria) aged to the late Oligocene to early Miocene. Five species of Palmoxylon were identified: P. daemonoropsoides (Unger) Kirchheimer, corr., P. chamaeropsoides Iamandei et Iamandei, sp. nov., P. coryphoides Ambwani et Mehrotra, P. sabaloides Greguss, P. trachycarpoides Iamandei et Iamandei, sp. nov. and P. phoenicoides Hofmann. Also found were two species of Rhizopalmoxylon (R. daemonoropsoides Iamandei et Iamandei, sp. nov., R. phoenicoides Iamandei et Iamandei, sp. nov.) and Palmocaulon sp. aff. Phoenix L. These new identifications add new elements to the forest assemblages of the Oligocene–Miocene Greek flora, useful for understanding the evolution of the Cenozoic palaeoclimate in the Aegean area.
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  • 3
    Publication Date: 2019-12-01
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  • 4
    Publication Date: 2019-12-01
    Description: Distinctive permineralized fruits of Baccatocarpon mohgaoense (Paradkar & Dixit) comb. nov. have been collected from several sites in the late Maastrichtian of the Deccan Intertrappean beds of Central India. We describe the peculiar fruits in detail, based on combined investigations by reflected light and X-ray CT scanning. Three-dimensional renderings and virtual slices confirm that the fruits have two lateral single-seeded locules and a central sterile chamber filled with parenchyma. The endocarp is thin-walled and opens apically longitudinal valves. Here we validate the generic name Baccatocarpon Bhowal & Sheikh ex Manchester, Ramteke, Kapgate & S.Y. Smith and recognize a single species, for which the name Baccatocarpon mohgaoense (Paradkar & Dixit) comb. nov. has priority. We document the occurrence of this species in cherts from the paleobotanical sites known as Bhutera, Keria, Mahurzari, Mohgoankalan, Paladaun, Marai Patan and Shibla. The systematic affinity of these fruits remains mysterious.
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  • 5
    Publication Date: 2019-12-01
    Description: The fossil genus Spinopalmoxylon from the Central European Oligocene and Miocene comprises three species: S. daemonorops, S. parvifructum sp. nov. and S. cicatricosum sp. nov. Here the species S. daemonorops is amended and its name is proposed as nomen conservandum against S. teutonicum. A series of synonyms is provided. In addition, two new species are described from late Oligocene deposits of Niederpleis: S. parvifructum sp. nov. (pistillate inflorescence, fruits, and seeds) and S. cicatricosum sp. nov. (staminate inflorescence and pollen). These three Spinopalmoxylon species together are proposed as a whole plant. Floras with the Spinopalmoxylon palm reflect the vegetation of the near-shore fluvial floodplain and back-swamp environments of the late Oligocene (Chattian) Köln Formation (Clay 1) and early Miocene (Burdigalian) Ville Formation (Seam 6A) in the northern foreland of the Siebengebirge Volcanic Field near Bonn, at the southeastern margin of the Lower Rhine Basin.
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  • 6
    Publication Date: 2019-12-01
    Description: Palynofloral assemblages are an invaluable source of information about the interactions between fossil plants and their environments. Here we describe a new Early Cretaceous palynoflora from the Lusitanian Basin in the Estremadura region of central western Portugal. A palynological assemblage of 28 genera and 40 species was extracted from 14 samples collected in the Vale Cortiço clay pit complex near the small village of Ameal (Torres Vedras Municipality). The source is a dark grey mudstone layer belonging to the lower part of the Santa Susana Formation, which is considered to be of early Hauterivian age. The palynoflora is dominated by fern spores and gymnosperm pollen. Bryophyte and lycophyte palynomorphs are also present but subordinate. Angiosperm pollen and algal or dinoflagellate cysts were not recognised in the studied samples. The palynological assemblage represents mixed conifer forest with the ground cover and understorey vegetation dominated by ferns, with patchy occurrences of bryophytes and lycophytes. A riverine environment with surrounding vegetation of open woodland and ground cover primarily of ferns is strongly indicated for the region.
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  • 7
    Publication Date: 2019-12-01
    Description: The Ul’ya flora comes from the Amka Formation of the Ul’ya Depression, located in the Okhotsk–Chukotka volcanic belt (North-East Russia). This flora includes ~50 species, among which conifers predominate. Ferns and angiosperms are also diverse. The Ul’ya flora is characterized by high endemism and by the presence of numerous Early Cretaceous relicts (Hausmannia, Podozamites, Phoenicopsis, Baiera, Sphenobaiera). Four new endemic species of conifers from the Ul’ya flora are described: Elatocladus amkensis Golovneva, sp. nov., Araucarites sheikashoviae Golovneva, sp. nov., Elatocladus gyrbykensis Golovneva, sp. nov. and Pagiophyllum umitbaevii Golovneva, sp. nov. Two-lobed leaves of Sphenobaiera are assigned to S. biloba Prynada based on their epidermal structure. Because of its systematic composition the Ul’ya flora is correlated with the Coniacian Chaun flora of Central Chukotka, with the Coniacian Aliki flora from the Viliga–Tumany interfluve area, and with the Coniacian Kholchan flora of the Magadan Region. The U-Pb age of zircon (ID-TIMS method) from plant-bearing tuffites within the Amka Formation at the Uenma River is 86.1 ± 0.3 Ma. Thus, Coniacian age (most likely the end of the Coniacian, near the Coniacian/Santonian boundary) is assigned to the Ul’ya flora and plant-bearing pyroclastic deposits of the Amka Formation on the basis of paleobotanical and isotopic data.
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  • 8
    Publication Date: 2019-12-01
    Description: The Sundarban Mangrove Forest in the Sundarban Biosphere Reserve, located at the mouth of the Ganga–Brahmaputra Delta in India, is the most diverse mangrove ecosystem in the world. Sediment cores were taken from two widely separated islands in that reserve: Chamta (CMT) and Sudhyanyakhali (SDK). Pollen analysis and radiocarbon dating were used to study the Holocene development and dynamics of this unique ecosystem. Modern pollen rain study reveals a strong relation between modern pollen rain and the present vegetation, as well as a high rate of Phoenix palludosa pollen production.The pollen records indicate that man-grove existed at CMT from ~5960 and at SDK from ~1520 cal yr BP. Changes in relative sea level, including the frequency and intensity of inundation as well as fluctuating precipitation, have been the major factors along with geomorphic processes that control the development and dynamics of the mangrove in the area during the Holocene. The mid Holocene mangrove at CMT declined, to be progressively replaced by successive communities, and eventually reached climax stage, while the SDK site is transitional in nature. The mangrove responds rapidly to changes in environmental conditions at both locations. Because of large-scale anthropogenic interventions, it is unlikely that similar rapid responses will occur in the future.
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  • 9
    Publication Date: 2019-12-01
    Description: The morphology of the adaxial structures of cones belonging to Palissya Endlicher 1847 emend. nov. are reinterpreted based on exquisitely preserved permineralised material from the Lower Cretaceous of Queensland. Although the material was not found in situ, it likely derives from the Orallo Formation, which is Valanginian in age. The cones have dual vascular bundles in each bract/scale complex, and the different tissue types in the bract and ovule/scale complex support interpretation of the cone as a compound structure. Since the early twentieth century it has been widely accepted that each ovule is surrounded by a cup-shaped structure, but the detailed morphology of the “cup” has hitherto been unclear. These new three-dimensionally preserved specimens with in situ ovules are described as Palissya tillackiorum sp. nov. This study demonstrates that the “cup” is formed from a pair of thin scales that subtend but are not fused to each ovule; each pair of scales comprises a thicker outer and thinner inner scale. The organographic relationships among ovules and scales in Palissya show a high degree of synorganisation. The adaxial surface of the bract/scale complex has 2–6 pairs of erect (orthotropous) ovules. The ovule/scale units are arranged symmetrically in two parallel rows on either side of the midline of the bract/scale. Individual ovule/scale units are comparable to those seen in extant Podocarpaceae and Taxaceae. The ovules are thin-walled and are interpreted to have a single integument and a non-thickened (non-lignified) micropyle. These new insights allow reinterpretation of material previously referred to Palissya. A new species is described from Yorkshire, England, as P. harrisii C.R. Hill ex Pattemore & Rozefelds sp. nov. All species based on well preserved cones are reconsidered herein: P. sphenolepis (Braun 1843) Nathorst 1908 emend. Florin 1958, P. elegans Parris, Drinnan & Cantrill 1995 emend. nov., P. bartrumii Edwards 1934 emend. nov., P. antarctica Cantrill 2000 and P. hunanensis Wang 2012. Palissya ovalis Parris et al. 1995 differs structurally from Palissya and is transferred to Knezourocarpon Pattemore 2000 emend. nov. Representatives of this genus may superficially resemble those of Palissya in compressions and impressions, and their congeneric status has been previously suggested; hence its inclusion in this study. Knezourocarpon has adaxial processes that are positioned in two parallel rows but it lacks ovules and paired lateral scales that formed a cup-shape, and its processes attach directly to a central vascular trace. The improved understanding of Palissya’s morphology allows for definite separation of these genera, although the higher-order affiliation of Knezourocarpon remains unclear.
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  • 10
    Publication Date: 2019-12-01
    Description: A new genus and species, Geminispermum virginiense, is described based on a well-preserved coalified cupulate reproductive unit recovered from the Early Cretaceous (early–middle Albian) Puddledock locality, Virginia, U.S.A. The reproductive unit is bisymmetrical and consists of an axis that bifurcates into two cupule-bearing stalks, each in the axil of a bract. Each cupule stalk bears a single non-valvate cupule recurved towards the center of the reproductive unit. The cupule opens distally by a short transverse slit with a distinct upper margin. Each cupule almost completely encloses a single orthotropous seed that is free from the cupule except at the base. The nucellus is also free from the integument except at the basal point of attachment. Geminispermum combines features of the ovulate structures of Caytoniales, Umkomasiales (= Corystospermales, including Doyleales) and Petriellales, but cannot be included in any of these existing orders as they are currently understood. The recurved, closed, non-valvate cupules are particularly similar to those of Caytonia, Petriellaea and Reymanownaea in external morphology, but differ in being one-seeded. The cupules of Geminispermum differ from the one-seeded cupules of Umkomasiales in being non-valvate and in having only a single cupule per bract. Geminispermum is perhaps most similar to the one- or two-seeded non-valvate cupules of Ktalenia from the Early Cretaceous of Argentina, but Ktalenia is poorly preserved, details of cupule architecture are uncertain, and the cupules appear to be associated with a single strongly dissected bract. Geminispermum is currently the only unequivocal seed plant cupule recovered from the Early Cretaceous Potomac Group and is distinct from all previously described cupulate reproductive structures.
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