Review of Palaeobotany and Palynology最新文献

The Schizaeaceae family consists of only two genera, Actinostachys Wall and Schizaea Sm. These genera are mainly found in the tropical regions of the Old and New World with a few of them growing in temperate areas. The spores of the following Schizaea species from America were studied: Schizaea elegans (Vahl) Sw., S. fistulosa Labill., S. fluminensis Miers ex J.W. Sturm, S. incurvata Schkuhr, S. poeppigiana J.W. Sturm, S. pusilla Pursh, S. sprucei Hook. and S. stricta Lellinger. The study was performed with light microscope (LM) and scanning electron microscope (SEM). The spores are monolete of 33.6–99.4 μm in equatorial diameter and 21–65.8 μm in polar diameter. The ornamentation of the spores is verrucate, verrucate-tuberculate, rugate or reticulate. The most abundant morphology is the verrucate ornamentation. The exospore and the perispore form the ornamentation of the spores. In most of the species analyzed abundant spheroids, variable in size were observed irregularly distributed on the spore surface, even on the laesura. This study describes and illustrates the spores of some species for the first time. The results are discussed with a recent phylogeny of the genus.

This study provides the first data on the relationship between chemical composition and biomechanical/physiological characteristics of foliar gymnosperm compressions from the Lower Cretaceous of Santa Cruz, Argentina. Studied taxa include: Squamastrobus tigrensis, Pseudoctenis ornata, Ginkgoites tigrensis, Ruflorinia orlandoi, and Ptilophyllum micropapillosum. The properties determined include: density, tensile strength (resistance to fracture), tensile modulus of elasticity (stiffness), and leaf mass per area (metabolic cost of tissue construction). They are calculated using a 3D-multivariate model based on data obtained by Fourier transform infrared (FTIR) spectroscopy and trait relationships linking density and the properties mentioned above. Samples have a predominantly aromatic chemical composition with variable carbonyl contents. The chemical groups detected are associated with diagenetically-resistant molecules, possibly including lignins, phenylpropanoids, tannins, and resin-like compounds. The results indicate that these plant taxa may have allocated variable amounts of resources (metabolic costs) for the development of aromatic, biomechanically resistant, and relatively long-lived foliar tissues. The determined chemical, biomechanical, and physiological properties of these leaves suggest their potential as a food source for herbivores. Thus, S. tigrensis leaves might have been unpleasantly astringent, difficult to eat and digest due to their hard tissues, and possibly even hazardous. Conversely, the leaves of G. tigrensis, P. ornata, R. orlandoi, and P. micropapillosum may have been easy to eat due to their softer tissues, offering food of intermediate-high nutritional value. The use of FTIR spectroscopy proves useful to perform detailed and realistic studies on the biomechanics, physiology, and autecology of extinct plants.

Aquatic palynomorphs have the potential to provide valuable insights into past environments but little has been done to assess the utility of freshwater dinoflagellate cysts as palaeoecological proxies of lacustrine environments. This study is the first to compare the distribution of freshwater dinoflagellate cysts found in surface sediments from 32 boreal lakes with varying physical and chemical characteristics. Cysts of Fusiperidinium wisconsinense, Parvodinium umbonatum, and Peridinium willei were nearly ubiquitous, but of the remaining cyst taxa, only Parvodinium inconspicuum, Peridinium limbatum, and Peridinium volzii were abundant but present in a smaller number of lakes. Assemblage composition broadly clustered into three groups: 1) an assemblage (primarily Peridinium spp.) associated with relatively shallow, mesotrophic lakes; 2) an assemblage dominated by F. wisconsinense in mesotrophic lakes with intermediate depth and relatively high pH and alkalinity; and 3) an assemblage dominated by P. umbonatum in deeper oligotrophic lakes. Moreover, changes in dinoflagellate cyst assemblage were assessed in a sediment core spanning the Holocene from nearby Gall Lake and interpreted alongside other previously published paleoecological proxies from this core. High abundances of many dinoflagellate cysts including P. limbatum, P. willei, F. wisconsinense, and P. inconspicuum were observed when lake production was high at a time when lake-levels were low and climate was more arid than today. This study suggests that dinoflagellate cysts in lacustrine sediments are, when abundant, promising both in modern and core samples, and the relationships between assemblages today and in the past can contribution additional information in understanding past ecological conditions.

Reconstructing the vegetation history of east China during the last glacial–interglacial transition is crucial for understanding the East Asian Summer Monsoon (EASM) evolution. Here, we present a new high-resolution pollen record from Chaohu Lake to determine the detailed process of regional lowland vegetation succession and its response to the EASM changes during the last glacial–Holocene transition (13.9–9.1 cal ka BP) in the lower Yangtze Valley, eastern China. During the Older Dryas (OD, 13.9–13.5 cal ka BP) period, regional forest-steppe indicative of co–dominance of Artemisia, Poaceae, and deciduous Quercus was present under a cool and dry climate. During the Allerød Interstadial (AI, 13.5–12.9 cal ka BP), significant arboreal expansions of deciduous Quercus, Hydrangea type and evergreen Quercus occurred, while herbs retreated significantly, presumably driven by the relatively warm, humid climate. Forest-steppe readvanced during the Younger Dryas (YD) interval, as indicated by increases in Poaceae and Artemisia, suggesting a cool and dry climate. During the early Holocene, extensive oak-pine forest flourished as regional vegetation, responding to pronounced climatic amelioration.

Our pollen-based climatic record is closely correlated with stalagmites δ¹⁸O records from EASM region and Greenland ice cores δ¹⁸O records, indicating the teleconnection between EASM variation and North Atlantic climate during the last deglacial–early Holocene. However, our record indicates an intensified EASM during the early AI and a prolonged onset excursion during the YD, diverging from North Atlantic climate but closely correlated to sea surface temperature (SST) variations in the western tropical Pacific.

Fupingopollenites, an extinct plant, has been suggested to belong to a family that originated in eastern Asia, where it was recovered from the early middle Eocene. It developed throughout the Oligocene in eastern Asia, expanding its geographical range and reaching maximum distribution and probably species diversity in the Miocene. In this study, we present the Fupingopollenites occurrences from different regions and ages in Türkiye: the middle-late Eocene transition from the Hatıldağ area (NW Türkiye), the middle-late Eocene transition from the Niğde-Ulukışla area (central Türkiye), the early Oligocene from the Ankara-Şereflikoçhisar area (central Türkiye), the Miocene from the Muğla area (SW Anatolia), and the Pliocene from the Isparta-Şarkikaraağaç area (southern Anatolia). Based on all new findings and published records, we suggest that the migratory route of this plant into Europe is across Türkiye. Furthermore, we can conclude that the suitable palaeoclimatic and palaeoenvironmental conditions for the flourishment of this pollen existed in Türkiye during the Eocene-early Oligocene. According to the numerical climatic estimates, the favorable mean annual temperature and the mean annual prepitation was ∼ 16 °C and 1000–1100 mm respectively. In addition, we suggest that the microclimatic conditions driven by the intense local tectonics in different depositional areas exerted a significant role in the distribution of this plant. In this study, the botanical relationship of Podocarpium podocarpum with Fupingopollenites has not been fully determined. However, it is noteworthy that both plants were identified in the macro- and micro-flora of Muğla and its surroundings in the Middle Miocene.

Pterophyllum, an extinct plant of Bennettitales, constitutes a significant component of the Mesozoic flora. In this study, we identified four fossil species of Pterophyllum from the Middle Jurassic Yaojie Formation in the Yaojie Basin and the Baojishan Basin in Gansu Province, Northwest China. Through analysis of macroscopic and macroscopic characteristics, these specimens were identified as Pterophyllum xinjiangensis Zhao, P. subaequale Hartz, P. ptilum Harris, and P. angustum (Braun) Gothan. These findings bridge gaps in the study of Bennettitales fossils in the region, affirming the warm and humid climate of the Yaojie Basin and the Baojishan Basin during the Middle Jurassic. Moreover, a comprehensive analysis of 598 reported Pterophyllum fossil records in China revealed that their occurrences from the Late Triassic to the Early Cretaceous was constrained by ancient climates and tectonic. The Late Triassic exhibited the highest diversity, with 83 species, which were widespread across warm-humid and tropical-subtropical zones in China; however, their diversity decreased sharply in subsequent periods, increased slightly in the Early Cretaceous, and then disappeared. In this paper, we further examined the habitat characteristics of this genera based on its spatiotemporal distribution and the paleogeographic and paleotectonic features of its origins, elucidating the coupled relationship between its distribution and ancient geographic and tectonic factors.

Taeniopterid leaves with entire margins, prominent midribs and simple or bifurcate lateral veins are present in many Paleozoic and Mesozoic floras globally and were a typical and diverse element in the late Paleozoic equatorial Cathaysian flora. Most taeniopterid leaves are preserved as impression-compression fossils that reveal only information on their morphology and in some cases cuticle structure. Taeniopterid leaves preserved with anatomy are much rarer and have only previously been identified in the Mesozoic. Here we report a taeniopterid leaf from the upper Permian Xuanwei Formation in southwestern China that preserves morphology and anatomy. The leaf is over 18 cm long and 10 cm wide, with the lamina attached to the lateral sides of the midrib. Parallel lateral veins arise from the midrib which has longitudinal ridges on its adaxial surface and two distinct groups of vascular bundles. One group of bundles is adaxially located and arranged in a rough inverted Ω-shape, while the other is abaxially located and arranged in a ring. Individual bundles have endarch primary xylem and secondary xylem. Comparisons with other anatomically preserved taeniopterid leaves allow us to establish Panxianopteris taeniopteroides gen. et sp. nov. This vascular bundle arrangement is most comparable to the rachis of the Triassic Umkomasiales pteridosperm leaf Dicroidium fremouwensis from the Gondwanan flora. P. taeniopteroides is the first anatomically preserved taeniopterid leaf reported from the Paleozoic and the Cathaysian flora, and although its affinity remains enigmatic because it is only known from its isolated leaf, it is likely to be a pteridosperm allied with the Umkomasiales or their ancestral lineage.

The Kansk Basin is one of the biggest reserves of brown coal in Russia. Jurassic coal-containing terrestrial deposits bearing plant remains crop out in several localities. This work is focused on five fossil-plant-containing localities in the Middle Jurassic Kamala Formation of the Kansk Basin within the Rybinsk Formational Zone. The studied material comprises 29 plant morphospecies. They are assigned to: Pteridophytes (Equisetites, Coniopteris, Cladophlebis and Raphaelia), Bennettitales (cf. Pterophyllum), Ginkgoales (Ginkgoites, Sphenobaiera and Eretmophyllum), Leptostrobales (Czekanowskia and Phoenicopsis) and Coniferales (Pityophyllum). There are several plants remains of uncertain systematic position, such as roots (Radicites sp.), cones and fossil wood. As a result, palaeoenvironmental interpretation was implemented; three taphonomic units were distinguished utilising complex palaeobotanical, lithofacial analyses, and literature-based data. Palaeoecological analysis identified three depositional environments with corresponding type of vegetation: a) periodically flooded alluvial plain dominated by Czekanowskia-Phoenicopsis; b) swamp-semiaquatic dominated by Equisetites, Coniopteris, Cladophlebis and Phoenicopsis; c) slope and upland vegetation dominated by Sphenobaiera, Ginkgoites, Eretmophyllum and Pityophyllum.

Dicroidium Gothan is an extinct seed fern that was widely distributed in Gondwana during the Triassic but has not yet been unequivocally recorded in Laurasia. In this paper, a new species of the genus, Dicroidium sinensis Sun et Deng sp. nov., is described from the Middle Triassic sediments of the Ordos Basin, northwestern China, based on macromorphology and cuticular structures. This is the first record of Dicroidium in China, indicating that the genus was not unique to Gondwana and was also present in Laurasia. Dicroidium seems to have originated in the palaeotropics in the Permian (e.g., Jordan) and then widespread and flourished in Gondwana and extended to Laurasia during the Middle-Late Triassic period, and disappeared in the Early Jurassic. This genus may have migrated from Jordan to Laurasia along the western coast of the Tethys. Additionally, galls found in the leaf of Dicroidium sinensis proves the interactions between plants and insects.