Composition and age span of sedimentary deposits of the Transantarctic Basin system vary between different regions of the Transantarctic Mountains. Moreover, whereas the regional stratigraphic successions have been very well established in some areas of East Antarctica, such as the Allan Hills or the Beardmore Glacier, they remain virtually unexplored in others. Here, we present the first palynostratigraphic age data for sedimentary deposits of the Victoria and Ferrar groups in the central Prince Albert Mountains (central Victoria Land). Productive palynological samples from carbonaceous mudstones at several sites around the Ricker Hills document a broad range of palynostratigraphic zones spanning the lower Middle Triassic to upper Lower Jurassic. These results help orient more detailed future sampling, but already clarify the correlation of these deposits with those from adjacent regions in southern and northern Victoria Land.

Premise of research. Tree ferns with an arborescent habit were diverse and ecologically significant throughout the Mesozoic; however, many taxa remain poorly understood as a result of their enigmatic morphologies and a sparse fossil record, particularly from northwestern Gondwana. Establishing their systematic affinities and evolutionary relationships is crucial to understanding Mesozoic forest ecology and fern evolution. Methodology. The new fossil material comes from deposits of Early Cretaceous (late Aptian) age in Colombia. The permineralized fossil was analyzed using thin sections and acetate peels. Phylogenetic and morphospace analyses were conducted to assess relationships and morphological similarities among Paradoxopteris, Alstaettia, Palmoidopteris, and Weichselia based on stem morphology and anatomy. Pivotal results. Paradoxopteris huertasii sp. nov. is distinguished by unique anatomical features including parallel meristeles and auxiliary strands. Phylogenetic and morphospace analyses support a potential "paradoxopterid" clade comprising Paradoxopteris and Weichselia. This hypothesis reinforces the recommendation to retain separate genus designations for foliage (Weichselia) and stem (Paradoxopteris) remains. Conclusion. Paradoxopteris huertasii provides critical anatomical data that advance understanding of paradoxopterid ferns and their evolutionary relationships. Resolving their affinities will require comprehensive anatomical study, reevaluation of historical specimens, and whole-plant reconstructions to clarify the diversity and systematics of Mesozoic tree ferns.

The Lower Devonian Rhynie cherts contain a wide variety of microfossils with possible affinities to fungi or fungus-like organisms, only a fraction of which have been described and critically evaluated. Philophrosyne beckeri gen. et sp. nov. occurs in accumulations of decayed plant parts interspersed with patches of microbial-mat communities. The specimens consist of a sac-like envelope with a diameter of 30–50 µm, filled with closely spaced spherules of equal or varying sizes with a diameter of up to 25 µm. In some specimens, a tubular subtending hypha is preserved, which either originates from a plant fragment or emerges from a microbial mat. The fossil is interpreted as an oomycete oogonium containing oospores, as small, club-shaped structures found on several specimens are strongly reminiscent of paragynous antheridia. Modern morphological equivalents exist within the order Saprolegniales. This discovery expands our knowledge of life forms in early terrestrial ecosystems that closely resemble modern oomycetes.

Early Jurassic volcanism was in the southern north Victoria Land portion of the Ferrar Large Igneous Province preceded by multiple phases of shallow-level intrusions of Ferrar sills into the 300 m thick cover of sedimentary rocks of the Triassic-Jurassic Victoria Group. Upward protrusions from sills into unconsolidated water-saturated sandstones triggered phreatomagmatic eruptions, forming discordant diatremes. Associated mafic volcaniclastic subaerial sediments are intercalated in the stratigraphic succession at two levels. Based on palynostratigraphy, their ages are late Pliensbachian and Early Toarcian, respectively. The matrix of the mafic volcaniclastic deposits is enriched in the individual minerals of the presently cemented fluviolacustrine country rocks. Clasts of the metamorphic and granitic basement are absent. The igneous clasts are comagmatic, comprising fragmented sill magma as well as scoriaceous juvenile lava shreds and bombs, some of which form welded deposits. All comagmatic and juvenile clasts, as well as those local pillows and lava flows embedded in the phreatomagmatic deposits, are of low-Ti andesitic composition (Cr < 80 ppm) and thus identical to the sills. Subsequent effusive volcanism (Kirkpatrick flows) started as low-volume lava flows and pillowed lava of more primitive low-Ti basaltic andesite composition (Cr > 100 ppm).

Regarded as one of the most important early Mesozoic Fossil-Lagersta & uml;tte, the Madygen Formation offers a unique window into a Ladinian-Carnian ecosystem established in the mid-northern latitudes of Pangaea. Despite the significance of this unit, its palaeobiota and the palaeoenvironmental conditions prevailing during its deposition remain incompletely understood. In this study, we present a detailed description of charcoalified gymnosperm wood remains from this formation. These charcoals, recovered from lacustrine strata, provide evidence for the occurrence of wildfire near the Ladinian-Carnian transition in the Madygen area. They also provide the first glimpse into the wood anatomical diversity preserved in the Madygen Formation, whose palaeoflora was previously known essentially from fossils preserved as impressions. This finding extends the current wildfire record for the studied interval and, together with the updated database of palaeo-wildfire proxies presented herein, suggests that such a phenomenon eventually occurred throughout the entire Ladinian and Carnian time span.

BACKGROUND AND AIMS:Royal ferns (Osmundales) are a family of leptosporangiate ferns, which today are limited to six genera in temperate and subtropical climate zones. In the Permian and Triassic, the order was much more diverse and globally distributed. The phylogeographical origins of the crown-group royal ferns have not yet been studied extensively. METHODS:Here, we present a new species of royal fern, Claytosmunda basilica sp. nov., from the Upper Triassic of Antarctica, analysed from thin sections and cellulose acetate peels of fossil rhizomes, and we implement a phylogenetic analysis of the royal ferns based on a morphological character matrix. KEY RESULTS:Claytosmunda basilica sp. nov. has a partly sclerotized pith and a moderately dissected xylem cylinder with prominent leaf gaps. Its two-layered cortex contains several sclerenchyma strands accompanying every leaf trace. Stipe bases show a heterogeneous sclerenchyma cylinder with two lateral masses of thick-walled fibres. Stipular wings contain large masses of sclerenchyma. Especially in its stipe base anatomy, C. basilica is remarkably similar to the extant Claytosmunda claytoniana. It also shares many characteristics with Claytosmunda beardmorensis from the Triassic of Antarctica, although both taxa have a completely different growth form. A close relationship between these three Claytosmunda species is supported by phylogenetic analysis. CONCLUSIONS:Phylogenetic analysis and the comparison of the geographical occurrences of all Permian and Triassic royal fern taxa reveals that crown-group Osmundales originated in the Gondwanan high latitudes, whereas other branches of the royal fern order that originated from tropical to subtropical latitudes went extinct after the Triassic.

Three distinct source areas contributed to sandstones of the Victoria Group within the Transantarctic Basin in southern North Victoria Land. During the Permian, quartzose sandstones were derived from erosion of the local Ross Orogen, likely from an uplifted swell in the area of today's Ross Sea, the Ross High. This source was still active during the sedimentation of lower parts of the Upper Triassic to Lower Jurassic Section Peak Formation. However, at that time the detritus derived from it was mixed with material from a then-active volcanic arc located in Zealandia at the Gondwana margin adjacent to North Victoria Land, indicating that the Ross High was no longer a significant morphological feature. The resulting lithic sandstones interfinger with quartzose sandstones that derive from a high-grade basement source. Within these quartzose sandstones, arc-derived material is a small, but up-section increasing contribution. Most of it is likely to originate from crustal blocks of Zealandia and West Antarctica. As the basin enlarged during its development, the quartzose material became increasingly more widespread in the upper part of the Section Peak Formation.

We report here an isolated insect forewing from Triassic deposits of the Eisenhower Range, northern Victoria Land, Antarctica. Based on the reduced venation (e.g. well-developed pterostigma, Rs dichotomously branched, Rs and M vein with five branches each), we tentatively identify the specimen as belonging to Permochoristidae (Mecoptera). However, due to incomplete preservation of the forewing, we prefer a determination under open nomenclature until more material of this taxon is available. The new specimen represents the first insect described from the Triassic of Antarctica and the first fossil record of Mecoptera in the continent, supporting the worldwide distribution and a greater diversity of the family during Triassic times.

Based on palynological data from a section in the Dead Sea region (Jordan), AHMAD et al. (2024) recently published an article in which the Umm Irna Formation was dated as Triassic. We strongly doubt that the studied samples are indeed from the Umm Irna Formation. Moreover, several of the identifications in AHMAD et al. cannot be confirmed. Some of the illustrated palynomorphs were clearly misidentified, while others were very poorly preserved and unidentifiable. A correct age assessment of the Umm Irna Formation is of crucial importance because of the unique composition of the macroflora.

Despite decades of active exploration in the Nile Delta, particularly in the offshore Mediterranean, the depositional settings and source rock potential of the Mesozoic strata remain unclear, primarily due to the limited number of drill cores. With its comprehensive approach, this study aims to fill gaps in our understanding of the Jurassic-Cretaceous paleoenvironments and source rock potential in one of the largest petroleum basins in Egypt and the Mediterranean region. The investigated successions are from the Abu Hammad-1 well in the onshore Nile Delta Basin, the only well that penetrated the Jurassic-Cretaceous in the basin. Our study presents an integrated palynological and organic geochemical approach, offering a comprehensive and reliable method for gaining precise insights and linking age dating to depositional environments, kerogen types, and thermal maturity. Palynological data are supplemented with organic geochemical analyses, comprising total organic carbon, Rock-Eval pyrolysis, biomarker, and elemental data. The obtained palynological results reveal two distinct assemblages, from younger to older, dated as Barremian-Aptian and Bathonian-Kimmeridgian, respectively. The studied sediments are derived from nearshore marine environments characterized by stable, oxygen-rich, suboxic bottom waters. This specific setting and proximity to the shoreline contribute to minimal preservation of organic matter. The organic content is dominated by Type III and Type IV kerogen, indicating a gas-prone source derived from terrestrial plant material and amorphous organic matter. Source rock characterization shows low thermal maturity. The study provides valuable insights into the Upper Jurassic and Lower Cretaceous geology of the Nile Delta Basin, facilitating the prediction of depositional environments and source rocks.

While decades of hydrocarbon exploration in the Gulf of Suez, Egypt, have yielded valuable insights, a significant opportunity remains to improve our understanding of the Upper Cretaceous strata through palynological research. In this context, the recent access to borehole drill cores from the Wata and Matulla formations presents an excellent chance to generate new findings and address the gap created by limited studies on the Cretaceous in this region. This study aims to address the existing gaps in our understanding of Late Cretaceous palaeoenvironments within one of Egypt’s largest petroleum basins. The analysed samples are from the OCT-A8 and GS197-2 wells in the October Oil Field, offshore from the central Gulf of Suez. By integrating palynological investigations with sedimentological data, we seek to deliver a comprehensive approach that yields precise insights into the depositional environments of these challenging reservoir units. Preliminary palynological results reveal a prevalence of non-marine palynomorphs in both studied rock units. We observed a dominance of Pediastrum and a relative scarcity of palynomorphs in the Wata Formation, while water ferns dominate the palynological composition of the Matulla Formation. The palynofacies or kerogen content was dominated by phytoclasts in both rock units. This indicates deposition in a highly proximal shelf basin near aquatic areas or wetlands, a finding that is similarly supported by the sedimentological data.

BACKGROUND AND AIMS:The complexity of fossil forest ecosystems is difficult to reconstruct due to the fragmentary nature of the fossil record. However, detailed morpho-anatomical studies of well-preserved individual fossils can provide key information on tree growth and ecology, including in biomes with no modern analogue, such as the lush forests that developed in the polar regions during past greenhouse climatic episodes. METHODS:We describe an unusual-looking stem from Middle Triassic (~240 Ma) deposits of Antarctica with over 100 very narrow growth rings and conspicuous persistent vascular traces through the wood. Sections of the specimen were prepared using the cellulose acetate peel technique to determine its systematic affinities and analyse its growth. KEY RESULTS:The new fossil shows similarities to the form genus Woodworthia and with conifer stems from the Triassic of Antarctica, and is assigned to the conifers. Vascular traces are interpreted as those of small branches retained on the trunk. Growth-ring analyses reveal one of the slowest growth rates reported in the fossil record, with an average of 0.2 mm per season. While the tree was growing within the Triassic polar circle, sedimentological data and growth-ring information from other fossil trees, including from the same locality, support the presence of favourable conditions in the region. CONCLUSIONS:The specimen is interpreted as a dwarf conifer tree that grew under a generally favourable regional climate but whose growth was suppressed due to stressful local site conditions. This is the first time that a tree with suppressed growth is identified as such in the fossil record, providing new insights on the structure of polar forests under greenhouse climates and, more generally, on the complexity of tree communities in deep time.

A new tree fern of the family Tempskyaceae, Tempskya hailunensis sp. nov., is described herein based on a silicified trunk from the Cretaceous of Hailun City, Heilongjiang Province, Northeast China. The new species is composed of dichotomizing large stems surrounded by a mesh of adventitious roots, petioles, and leaf-like structures, constituting a solid and compact false trunk. The dorsiventral stems contain solenosteles that have long internodes with mostly two leaf traces. The stem cortex consists of a sclerenchymatous outer zone and a parenchymatous inner zone, and the stem pith is divided into a parenchymatous outer zone and a sclerenchymatous inner zone. Wide multicellular scales are attached to the stem epidermis. Leaf-like structures embedded among adventitious roots in the trunk are isobilateral, thick, and without distinct intercellular spaces. Also present are dispersed annuli of sporangia, which are only few cells long and apparently uniseriate. Though it cannot be fully ruled out that these vegetative and fertile remains belong to epiphytes that colonized the Tempskya trunk, the consistent and exclusive occurrence of these particular types of remains makes it likely that they belonged to the Tempskya plant itself. This new species represents only the second fossil record of Tempskya from China, increasing the known diversity of this genus during the Cretaceous both in Asia and globally. Moreover, it provided evidence for recognizing probable leaf structure and growth habit of Tempskya.

During the 11th German Antarctic North Victoria Land Expedition in 2015/16, exceptionally well-preserved permineralized Kykloxylon stems—the wood of the iconic Dicroidium plants of the Gondwanan Triassic—were collected from the Middle to Upper Triassic Helliwell Formation in north Victoria Land, Transantarctic Mountains, Antarctica. Some of these logs show large borings and cavities that are partly filled with multi-layered periderm. This periderm is identical in cell shape and dimensions to isolated flakes of tissue that are superabundant in bulk macerations of Dicroidium-bearing rock samples from different coeval locations in the Transantarctic Mountains. These flakes are interpreted as shed bark fragments of Dicroidium-bearing umkomasialean trees. Various hypotheses on the adaptive advantages of bark shedding are discussed, including the reduction of epiphyte load. Palynological data document an abundance of potentially epiphytic cryptogams (spikemosses and bryophytes) in the environments in which the Dicroidium trees grew, and modern ecosystems with a climate comparable to that of the Late Triassic in Antarctica are in many cases also characterized by a lush epiphyte vegetation. Another advantage could lie in the reduction of infections by phytopathogenic microorganisms, as abundant fungal remains in both the wound periderm and the dispersed periderm flakes indicate.

Sedimentary interbeds between lava flows of the Early Jurassic Kirkpatrick Basalt, East Antarctica, are long known to contain abundant fossil wood, including in situ-preserved tree trunks. Following an initial brief report containing only preliminary taxonomic assessments, however, these trunks have never been studied in greater detail. Here, we provide a detailed wood-anatomical description of in situ trunks and associated float specimens of fossil wood from several localities in the Mesa Range. Four genera are identified: Agathoxylon Hartig, Brachyoxylon Hollick et Jeffrey, Mixoxylon Chernomorets et Sakala and Protocupressinoxylon-type wood. This set completely challenges the image that prevailed until now of a little diversified paleoxyloflora in Antarctica during the Jurassic.

Silicification - the precipitation of silica within the remains of a buried organism - allows for the three-dimensional preservation of a fossil in minute cellular to subcellular detail and forms the basis for some of the most spectacular Lagerstätten for terrestrial ecosystems (e.g. Selden & Nudds 2004). Among these are the plant-bearing chert deposits of the Transantarctic Mountains, which were discovered by J.H. Mercer and J.D. Gunner during the 1969/1970 ‘Beardmore Expedition’ and sampled and first screened by J.M. Schopf soon thereafter (Schopf 1970). The collection, preparation and in-depth study of plant-bearing cherts from the Beardmore Glacier generated more than 125 publications, and systematic treatments of the permineralized biotas resulted in the description of 30 genera and almost 50 species of structurally preserved plants and fungi. The exquisite anatomical preservation enabled unusually detailed reconstruction of many of the preserved organisms, yielding the most completely known fossil members for several groups of gymnosperms (see Escapa et al.2011). Together with similar silicified peat deposits from the remote Prince Charles Mountains in East Antarctica (McLoughlin & Drinnan 1997), these conservation-Lagerstätten of the Transantarctic Mountains constitute an extraordinary window into the biology and ecology of late Palaeozoic and early Mesozoic high-latitude terrestrial ecosystems. Perhaps the single most important of these deposits is the silicified peat from the Triassic Fremouw Formation at Fremouw Peak in the Beardmore Glacier area. Triassic silicified peat also occurs elsewhere in the Transantarctic Mountains, including the Allan Hills in southern Victoria Land (Taylor & Taylor 1990) and Timber Peak in northern Victoria Land (Bomfleur et al.2011), but thus far the quality of preservation at other sites proved too poor to merit in-depth study.

Silicified conifer wood assignable to Xenoxylon meisteri from the Upper Cretaceous of northeastern China provides evidence of the presence of wood-degrading fungi and xylophagous arthropods, and also indicates the existence of a relationship between fungi and arthropods. Evidence of arthropod activities occurs in the form of vertical and horizontal borings that are lined on the inside with small coprolites. The borings are much larger (up to 2.4 mm in diameter) than the coprolites (74e127 mm in diameter), suggesting that two different animals, a larger one that made the borings and a smaller one that produced the coprolites, lived in them, either simultaneously or one after another. The wood in the surroundings of the borings contains different types of fungal remains. Especially abundant are slender, septate, and multi-branched hyphae on which thick-walled chlamydospores and other hyphal inflations are formed. Hyphae traversing from one host cell to another usually produce a swelling close to where they enter the cell wall. Decay holes in the infected wood suggest that this fungus was a wood-degrading saprotroph, probably a member of the Ascomycota. The fungus also occurs inside the arthropod borings, where it forms chains of barrel-shaped cells, likely conidia, suggesting that the arthropods may have served as dispersal vectors for the fungus. Xenoxylon meisteri provides the first indication of a tripartite plant-arthropod-fungal association from the Mesozoic of China, and gives new insights into the complex network of organismal relationships that existed in Cretaceous terrestrial ecosystems. (c) 2024 Elsevier Ltd. All rights reserved.

The end-Permian mass extinction (EPME) is the largest extinction event of the Phanerozoic, but the specific causal pathways, especially in the terrestrial realm, are unresolved. Malformed pollen and spores recovered from the EPME interval have been taken as indicators of extreme environmental stress in terrestrial ecosystems. However, whether they relate to volcanism-driven ozone-layer deterioration and enhanced ultraviolet-B (UV-B) flux, or volcanogenic toxic pollutants including mercury and acid rain, or some combination of the two, remains unclear. Here, we take advantage of a novel palynological proxy, which utilises the ability of land plants to adjust the concentration of protective UV-B-absorbing compounds (UACs) in the outer wall of their reproductive propagules in response to changes in ambient UV-B flux. We analysed UAC abundances in ca. 800 pollen grains from an independently-dated Permian-Triassic boundary section in southern Tibet, in order to infer changes in UV-B-radiation flux at the Earth’s surface during the EPME. Our data reveal an excursion in UACs that coincides with a spike in mercury concentration and a negative carbon-isotope excursion in the latest Permian deposits, suggesting a close temporal link between large-scale volcanic eruptions, global carbon- and mercury-cycle perturbations, and ozone-layer disruption. Because enhanced UV-B radiation can exacerbate the environmental deterioration induced by massive magmatism, ozone depletion is considered a compelling ecological driver for the terrestrial mass extinction.