Search

Premise of research. Climbing plants are important components of modern-day tropical forests and primarily comprise angiosperms, but in Paleozoic tropical forests, pteridosperms were the dominant c...

Phylogenetic divergence-time estimation has been revolutionized by two recent developments: 1) total-evidence dating (or "tip-dating") approaches that allow for the incorporation of fossils as tips in the analysis, with their phylogenetic and temporal relationships to the extant taxa inferred from the data and 2) the fossilized birth-death (FBD) class of tree models that capture the processes that produce the tree (speciation, extinction, and fossilization) and thus provide a coherent and biologically interpretable tree prior. To explore the behavior of these methods, we apply them to marattialean ferns, a group that was dominant in Carboniferous landscapes prior to declining to its modest extant diversity of slightly over 100 species. We show that tree models have a dramatic influence on estimates of both divergence times and topological relationships. This influence is driven by the strong, counter-intuitive informativeness of the uniform tree prior, and the inherent nonidentifiability of divergence-time models. In contrast to the strong influence of the tree models, we find minor effects of differing the morphological transition model or the morphological clock model. We compare the performance of a large pool of candidate models using a combination of posterior-predictive simulation and Bayes factors. Notably, an FBD model with epoch-specific speciation and extinction rates was strongly favored by Bayes factors. Our best-fitting model infers stem and crown divergences for the Marattiales in the mid-Devonian and Late Cretaceous, respectively, with elevated speciation rates in the Mississippian and elevated extinction rates in the Cisuralian leading to a peak diversity of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{upgreek} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} }{}${\sim}$\end{document}2800 species at the end of the Carboniferous, representing the heyday of the Psaroniaceae. This peak is followed by the rapid decline and ultimate extinction of the Psaroniaceae, with their descendants, the Marattiaceae, persisting at approximately stable levels of diversity until the present. This general diversification pattern appears to be insensitive to potential biases in the fossil record; despite the preponderance of available fossils being from Pennsylvanian coal balls, incorporating fossilization-rate variation does not improve model fit. In addition, by incorporating temporal data directly within the model and allowing for the inference of the phylogenetic position of the fossils, our study makes the surprising inference that the clade of extant Marattiales is relatively young, younger than any of the fossils historically thought to be congeneric with extant species. This result is a dramatic demonstration of the dangers of node-based approaches to divergence-time estimation, where the assignment of fossils to particular clades is made a priori (earlier node-based studies that constrained the minimum ages of extant genera based on these fossils resulted in much older age estimates than in our study) and of the utility of explicit models of morphological evolution and lineage diversification. [Bayesian model comparison; Carboniferous; divergence-time estimation; fossil record; fossilized birth–death; lineage diversification; Marattiales; models of morphological evolution; Psaronius; RevBayes.]

This paper investigates the taxonomic diversity of marattialean stems from the family Psaroniaceae preserved in-situ within the Wuda Tuff Flora. Three species of the permineralized stem Psaronius and eight species of the compression/impression stem Caulopteris are documented, but it has not been possible to associate the anatomically preserved species with the compression/impression ones due to preservational limitations. The higher diversity of Caulopteris species may relate to anatomical features that could distinguish additional species of Psaronius not being preserved, or it may reflect the rarity of anatomical preservation in the flora limiting the available dataset and it is also possible that a “generalized” Psaronius anatomy was common to several stem species showing distinct leaf scars (Caulopteris) and distinct leaves (Pecopteris). The eight species of Caulopteris recorded are very close to the previously reported diversity of nine species of the vegetative leaf Pecopteris from the Wuda flora, which also indicates a high diversity within the family. However, intraspecific variation makes the identification of species of Pecopteris and Caulopteris rather difficult, potentially inflating the taxonomic diversity of these genera. We show that Psaronius stems from the Wuda flora include one species from the Psaronius blicklei-group, one species that shares characters with both Psaronius blicklei and Psaronius panxianensis groups, and one species that shares characters with Psaronius blicklei-group but possesses a unique one different from both Psaronius blicklei and Psaronius panxianensis groups. These species appear to represent transitional forms evolved from the Carboniferous–Cisuralian (early Permian) Psaronius blicklei-group that are on the evolutionary lineage leading to the Lopingian (late Permian) Psaronius panxianensis-group. In addition, a single occurrence of a stem of Psaronius in organic attachment to a tri-pinnate frond of Pecopteris orientalis (Schenk) Pot. is documented, representing an important starting point for future Psaroniaceae whole-plant reconstructions within the Cathaysian flora.

Much is known about the biology and ecology of the plants that comprised the forest ecosystems during the Carboniferous and Early Permian. However, a broad understanding of the interrelatedness between the plants and other organisms living in these forests has been slow to develop. The tree fern Psaronius (Marattiales), an important element in many Pennsylvanian and Early Permian peat-forming forest ecosystems, gained mechanical stability from a massive root mantle. Thin sections of a permineralized Psaronius root mantle from the Manebach Formation (Asselian, Lower Permian/Cisuralian) near Ilmenau, Germany, show a diverse assemblage of predominantly intracellular fungi in all root tissues. Especially interesting is a fungus that produces prominent, boot-shaped swellings close to where it passes through host cell walls and what appear to be physiological interfaces comprised of short, densely clustered hyphal branches within the host cells. Other fungal remains occur in the form of chytrid-like sporangia, several types of basidiomycete hyphae with simple, medallion, and ampulliform clamp connections, and tenuous mycelia resembling present-day ‘fine endophytes.’ This fungal assemblage represents one of the best preserved Carboniferous-Early Permian fungal communities documented to date. It strengthens the hypothesis that plant-fungus associations were highly diverse and complex in late Paleozoic forests, likely because many plants in these ecosystems were long-lived and complex in morphology and internal organization, and thus provided multiple contact sites and ecologically distinct microhabitats for fungi.

This work presents a new fossil plant-bearing area located in the municipalities of Duque Bacelar and Coelho Neto, Maranhao State, Brazil, recovered from lower Permian (Cisuralian) strata of the Pedra de Fogo Formation, northeastern portion of the Parnaiba Basin. The area comprises more than five exposures with assemblages formed mostly of large gymnosperm woods, a number of them in life-position (reaching up to ∼2.30 m in height and 1.15 m in diameter) and, in lesser degree, of horizontal tree-fern stems (up to 5 m in length), some of them being referable to Psaronius sp. The fossils are recorded in sedimentary beds of continental origin that accumulated in shallow, nearshore areas of large lakes, which eventually were affected by rapid burial episodes generated by non-channelized, high energy fluvial systems. The new fossil assemblages are included within lacustrine rocks placed at the base of the Pedra de Fogo Formation, i.e., Silex Basal Member, near the contact with the underlying Piaui Formation (Pennsylvanian). This observation contrasts with previous studies at the southwestern portion of the basin, where the stratigraphic position of plant fossils is referred to the upper Pedra de Fogo Formation (Trisidela Member) or even to the overlying Motuca Formation. The new sites currently suffer damage from human activities and require urgent actions in order to protect them. Based on the current laws, some measures of protection for these sites are discussed and proposed herein.

The first record of an anatomically preserved flora from Stephanian outcrops at Arnao beach (Asturias, Spain) is presented. The stratigraphic section is part of a geological heritage site that preserves exceptional Devonian reef deposits. The Carboniferous succession contains coal seams worked by one of the earliest mines in Spain and its plant-fossil assemblages were reported in the 19th century but scarcely revised later. The new assemblages recovered in the beach, during extreme low tides, represent the first record of permineralised trunks in northwestern Spain. Large cordaitalean specimens are referred to a new species of Cordaixylon characterised by non-septate pith, araucarian radial pitting of the tracheids and cross-fields with phyllocladoid pits. Part of the root mantle of Psaronius is preserved in water-worn pebbles, indicating the presence of tree ferns in the palaeoflora. The associated compression/impression assemblage includes lycophytes, sphenophytes, pteridosperms and pteridophytes. A comparison of the assemblage confirms its importance for reconstructing the Late Pennsylvanian floral succession in the region. Fil: Cesari, Silvia Nelida. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina Fil: Álvarez Vázquez, Carmen. Real Jardin Botanico de Córdoba; España Fil: Méndez Bedia, Isabel. Universidad de Oviedo; España Fil: Álvarez Laó, Diego. Universidad de Oviedo; España Fil: Turrero, Pablo. Universidad de Oviedo; España Fil: Arbizu, Miguel. Universidad de Oviedo; España

Three typical plant taxa from the fossil assemblage of the 290-million-year-old Chemnitz Petrified Forest (Zeisigwald Tuff Horizon, Leukersdorf Formation) were studied with regard to the microstructure of the petrifactions: samples of the tree fern Psaronius sp., the seed fern Medullosa stellata, and the gymnosperm Dadoxylon sp. The plant’s tissues are anatomically preserved by silica exhibiting different crystalline order and by other mineralisations. Specimens were studied by means of electron backscatter imaging and electron backscatter diffraction in a scanning electron microscope. The cell walls were largely preserved by quartz crystals, the cell lumina by cryptocrystalline silica. The former organisation and chemical composition of the vascular tissue are mirrored by varying grain formation and grain size. Results are discussed in terms of extant xylem cell wall organisation showing highly hydrophilic cellulose and hemicellulose cross-linked by hydrophobic lignin. The effect of polar and non-polar wood components on the precipitation of silica from aqueous solution and on the formation of crystals is convincing, and the reported results provide a better understanding of how silica replaced organic matter during the petrifaction process.

A recently excavated locality in the Chemnitz Petrified Forest, lower Permian in age and occurring within the Leukersdorf Formation of the Chemnitz Basin, Germany, provides evidence for an outstanding fossil assemblage buried in situ by pyroclastics. The environment is interpreted as forested lowland that sheltered a dense hygrophilous vegetation of ferns, sphenophytes, and gymnosperms, as well as a diverse fauna of reptiles, amphibians, arthropods, and gastropods. A detailed measured section of the outcrop documents the early volcanic history of the Chemnitz fossil forest, including a paleosol that shows the root systems of Psaronius tree ferns, Arthropitys calamitaleans, and Medullosa and Cordaixylon gymnosperms in the same horizon. Fifty-three trunks are still standing upright and rooted at their place of growth, providing evidence that the top of the paleosol was the land surface on which the forest grew, thereby offering insights into the original plant community structure and density. Taphonomic analysis of both the petrified and adpression-fossil assemblages enable us to reconstruct the direction, estimate the violence and extent of the volcanic events, and their effects on the entire ecosystem. A complete dataset of three-dimensional coordinates resulting from three and one-half years of continuing excavation and study permits the recognition of organ connections and results in the first reconstructions of the excavation site, the floral elements, and the plant community as a whole.

We describe moderately diverse but extremely widespread calcified plant assemblages from the Pennsylvanian (mid/late Bolsovian–Asturian) Pennant Sandstone Formation (Warwickshire Group) of southern Britain, based on museum collections and new field discoveries. Fossils are documented from 21 sites where they comprise allochthonous accumulations within channel-lag conglomerate and coarse-grained sandstone facies of large, braided river channels draining the Variscan Orogen. Assemblages are dominated by cordaitaleans (87% of total, Amyelon , Mesoxylon , Dadoxylon ), with a few tree-ferns (7%, Psaronius ), and rare pteridosperms (1%, Myeloxylon ), sphenopsids (2.5%, Arthropitys ) and lycopsids (2.5%, ‘ Lepidodendron ’). These fossils clearly derived from a different plant community to those found in the coal seams (mixed fern/lycopsid-dominated based on palynofloras) and roof shales (pteridosperm-dominated based on megafloral adpressions), which occur between the fluvial sandstone deposits. Two competing hypotheses to explain these compositional differences are that (1) permineralised plants grew in extra-basinal settings adjacent to areas of Coal Forest or (2) permineralised plants grew on lowland interfluves during times of drier climate when Coal Forests had temporarily retreated. Data are currently insufficient to test between these hypotheses although the calcified preservational mode suggests burial under seasonally dry conditions.

We report well-preserved coprolites in the ground tissue of the permineralized stem of Psaronius housuoensis D'Rozario et al., from the Upper Permian deposits of Yunnan Province, southwest China. The distinctive coprolites are circular to oval in shape, ranging on average from 944 × 1190 μm to 1065 × 1120 μm, and contain histologically identifiable tracheids, parenchyma, gum sac cells, spores and fungal remains. Several lines of evidence indicate that this association was detritivorous, represented a pith boring, and was made by a diplopod or more likely an insect. This discovery extends the temporal duration of the food web of Psaronius plant–arthropod associations from the late Middle Pennsylvanian to now the Late Permian, and extends the biogeographic range from the equatorial wetlands of the Illinois, Northern Appalachian, and German Erzgebirge Basins of Euramerica to now the South China Block of Cathaysia. The Psaronius –arthropod–fungi component community is spatiotemporally the most persistent of documented Paleozoic associations in the fossil record.

A marattialean trunk of Psaronius laowujiensis sp. nov. is described from the Upper Permian of the Xuanwei Formation, Panxian County, Guizhou Province, South China. The specimen most likely represents the lower part of the trunk, because the preserved thickness of the root mantel is somewhat larger than the diameter of the stem. Meristeles of the stem are arranged in approximately five tangential stelar cycles but not in radial files. Inner meristeles are in small number, ∼12–13, and loosely arranged. Leaf traces diverge helically and are organized in a 2/5 phyllotaxy. The leaf base vascular configuration consists of three strands that include a large U‐shaped, centrifugal strand, a small centripetal strand, and an inverted Ω‐shaped internal strand. A vascular bundle sheath one or two cell layers thick surrounds each meristele. Within the centripetal concavity of each peripheral cauline bundle there are anchor‐shaped sclerenchymatous strands. Ground tissue appears to consist of aerenchymatous parenchyma, ...

The relationship between the actual anatomy of silicified plants and the nature of their permineralization has yet to be fully understood from a mineralogical point of view. Thin sections of silicified trunks obtained from the extinct Permo-Carboniferous arborescent plant taxa Arthropitys GOEPP., Psaronius COTTA and Dadoxylon ENDL., were studied by transmitted normal light (PPL), polarized-light (XPL), hot or scanning cathodoluminescence (CL), and electron microscopy (SEM) with energy and wavelength dispersive X-ray analysis (EDS and WDS). X-ray diffraction analysis (XRD) indicates that the SiO 2 phase is highly crystalline, probably due to its extreme age (approximately 300 million years). The cathodoluminescence of the silicifed trunks is seen to be unique and related to the petrographical characteristics of SiO 2 matter, which is closely connected to variation in plant anatomy. Microquartz (up to 20 μm) and fine megaquartz crystals (20–50 μm) generally produced red CL. They are present in most of the former plant tissues, especially in parenchyma and sclerenchyma, and also in cell walls and lumina of tracheids and rays of the secondary xylem. They almost completely reflect the original anatomical structures and as polyblastic textures preserve them best. Thick-walled sclerenchyma cells are usually best preserved, tracheids with lignin thickenings to a lesser extent. In contrast, megaquartz (above 50 μm) with brownish-red CL, spherulitic chalcedony with pinkish-purple or light violet CL, and agate-like structures sometimes crystallized as hyperblastic textures irrespective of the original plant tissues. This occurred especially in former thin-walled parenchyma, aerenchyma, voids, and in empty spaces and cracks. Parenchyma is thus well preserved only occasionally but aerenchyma is always transformed to an undifferentiated mineral phase. In the SiO 2 ground-mass, stable red CL prevails and blue CL is less common. CL sometimes allows visualisation of important fine scale anatomical detail that is not obvious under normal transmitted light. Furthermore, in several cases short-lived blue CL was recorded, which revealed a secondary overprint caused by a later silicification phase. CL also revealed traces of earlier calcification (orange CL). Detrital mineral grains, trapped in a compact silicified body (easily exposed by CL and analyzed by SEM/EDS) can serve as a clue to plant taphonomy, as for example black sands in “mineral pockets” probably indicate well-sorted sedimentary units from original riparian environments.

A new species of the marattialean fern trunk Psaronius Cotta is described from the Upper Permian Cathaysian flora in the Xuanwei Formation of Guizhou Province, SW China, and named P. panxianensis sp. nov. Stems possess a helically diverging sequence of leaf traces organized in a 2/7 phyllotaxy and are characterized by stages of leaf trace development that include an early ontogenetic stage with a single vascular bundle (Stewartiopteris-type), a middle stage with two vascular bundles (Stipitopteris-type), and a late stage with three vascular bundles. Roots diverge singly or occasionally in pairs, arising alternately from the centrifugal surface of the peripheral cauline bundles (PCB) near the tip, and form both bound and free root mantles. This species is distinguished from all previously recognized species from the Euramerican and Gondwana floras in having an anchor-shaped sclerenchymatous strand internal to the PCB and a large V-shaped strand formed by the connection of two anchor-shaped strands. Psaronius panxianensis sp. nov. is important as its leaf traces show three distinct ontogenetic development stages within the trunk, with this organization interpreted as a derived condition within psaroniaceous marattialean fern evolution. In the stem abundant air space suggests that P. panxianensis lived in waterlogged substrates with aerenchyma facilitating gaseous exchange. However, the presence of marattialean fern dominated communities in the Upper Permian of SW China suggest an overall drying trend with these plants replacing earlier lycopsid and sphenopsid dominated wetland communities.

Because biogeography offers insights into distribution patterns, species richness, and biological diversity of organisms, and more importantly, into the dynamics of organic evolution, this article explores the biogeography of specific groups of insects, which induce galls on plants in the Orient and the eastern Palearctic. The capability to induce galls occurs only in specific groups of insects. Leaf-mining habit in plant-feeding insects from the Upper Cretaceous possibly led insects to seek new food sources and their larvae preferring specialized, but limited, feeding sites on plants of the Eocene, which must have coincided with the diversification and establishment of angiosperms. Integration of monophagous host-selection behavior and evolution of other related adaptive strategies in insects, sometime in the Miocene-Pleiocene, must have predisposed gall-inducing behavior among insects. Nonetheless, discovery of a holometabolan-induced gall on the fronds of Psaronius (Filicopsida: Marattiales) f...

Two outstanding Permian petrified forests, those of Chemnitz, in Germany, and northern Tocantins, in Brazil, contribute to the understanding of the composition, peculiarities and dynamics of Early Permian wetland ecosystems. These assemblages represent seasonally influenced, essentially contemporaneous but quite comparable, tree-ferndominated plant communities in the Northern and Southern Hemispheres. The Chemnitz fossils are embedded in coarse-grained pyroclastics of the Zeisigwald Tuff Horizon (Leukersdorf Formation, Erzgebirge Basin), whereas those of Tocantins occur in different lithofacies of a cyclic alluvial succession (Pedra de Fogo/Motuca formations, Parnaiba Basin). The outstanding three-dimensional preservation of particularly large fossil remains, made possible by siliceous permineralization, provides the opportunity to study the gross morphology, anatomy and internal organization of plant tissues, as well as taphonomical and ecological aspects of late Palaeozoic plants in a way not allowed by other preservational states. Recent studies of newly collected material permit a re-evaluation of the popular reconstructions of Early Permian floras. Various plant–plant and plant–animal interactions add to our understanding of two diverse lowland ecosystems that, irrespective of their different palaeogeographic position and taphonomic modes, show striking similarities. There is no doubt that land plants have played an important role in shaping both terrestrial ecosystems and landscapes through time. They have not only played a striking role in the global carbon cycle (Berner & Kothavala 2001), they also affect weathering and soil-forming processes, constitute the basis of terrestrial food chains, frame habitats for all terrestrial animals, and, shape and develop the terrestrial biota in general. During the late Palaeozoic, plant life rapidly adapted to diverse terrestrial landscapes and conditions, thus creating a set of advanced ecosystems (e.g. Falcon-Lang & Bashforth 2004). Some differed more or less from the well-known tropical wetlands, which are generally favoured with respect to preservation. In Permian times, one recognizes a considerable decrease in the fossil plant record compared with the Carboniferous. Most of the coeval ecosystems, including those of the hinterland areas, remain highly enigmatic, and the depositional sequence is usually less complete (Schneider 1989; Kerp 1996, 2000). Due to the tectonic and palaeogeographic evolution, which considerably influenced the depositional environments, accommodation space and climatic regimes on a variable scale, most of the terrestrial Permian is represented by hiatuses or largely unfossiliferous strata. Localities that provide a rich fossil record are rare and especially noteworthy. A few of them became known as so-called ‘petrified forests’, viz. localities where numerous petrified trees have been fossilized essentially in a growth position, making them particularly instructive. Petrified forests are known from both volcanic deposits and clastic sediments from the Devonian onwards and are more widespread than commonly thought. However, only a few examples are known from the Palaeozoic, such as the regionally restricted fossil forest of Chemnitz, in Germany (Sterzel 1875, 1918; Barthel 1976; Rossler 2001) and the rather spatially extended fossil forest of Tocantins in northern Brazil (Dias-Brito & Castro 2005). Some currently wellknown fossil generic names, such as Psaronius, Arthropitys and Medullosa, are based on finds from Chemnitz, the locus typicus and one of the richest localities of Permian permineralized plants. Scientific investigation of the Chemnitz site dates back to the early history of palaeobotany around the early nineteenth century (Sprengel 1828; Cotta 1832). Tocantins, in contrast, is a long-known, but poorly studied site that has recently yielded a rich array of Lower Permian plant fossils (Herbst 1999; Rossler & Noll 2002). New finds from the Southern Hemisphere, considerably exceeding the long-known Psaronius brasiliensis material, have lead to notable progress in research on late Palaeozoic plants, such as different ferns, From: LUCAS, S. G., CASSINIS, G. & SCHNEIDER, J. W. (eds) 2006. Non-Marine Permian Biostratigraphy and Biochronology. Geological Society, London, Special Publications, 265, 39–63. 0305-8719/06/$15.00 © The Geological Society of London.

The Tedeleaceae are late Paleozoic Filicalean ferns with two known genera, Ankyropteris and Senftenbergia, which partially overlap morphologically and have the same known stratigraphic ranges—Namurian A to Lower Permian in Euramerica. Ankyropteris is anatomically known and Senftenbergia is almost exclusively based on compression specimens. Both genera exhibit abaxially, laminar-borne sori and/or solitary sporangia with some schizaeoid attributes. The sporangia are pyriform to tear-drop shaped, erect to slightly curved with a two to multiseriate apical annulus and mature spores usually of the Raistrickia type. Detailed morphological comparisons of Ankyropteris with Senftenbergia emphasize generic overlaps as well as lack of congruence. Ankyropteris brongniartii, a classic vine in anatomy, defines the stratigraphic range of the genus and provides recurrent ecological observations of habit and associated plants in ecotonal swamp reaches as well as in volcanic environments and on other clastic substrates. Ankyropteris may have originated from the clepsydroid zygopterid clade outside of the swamps. Ankyropteris brongniartii occurred as an epiphytic vine on Psaronius tree ferns as they expanded into coal swamps and often co-occurred with Paralycopodites even earlier in Middle Pennsylvanian. Vine stem anatomy and functional morphology of aphlebiae are emphasized in A. brongniartii with comparisons to Austroclepsis, an early “vining” false tree fern. Anatomical comparisons of Ankyropteris species based on shoots emphasize divergent habits with similar robust sizes; all exhibited aphlebiae. Known only from coal balls, Ankyropteris corrugata (Westphalian A–B) had a rampant habit on exposed peat with a succulent, dichotomous rhizome and erect fronds. The Lower Pennsylvanian specimen of Ankyropteris hendricksii is a compact tree fern with crowded frond bases and intercalated roots. Tyloses commonly occur in A. corrugata and A. brongniartii indicating water-stressed conditions. Apical meristems of shoot and fronds are reported for the first time, suggesting response growth to disturbance and rapid burial.

The Late Pennsylvanian Graissessac-Lodève basin is a small, fluvio-palustrine depocenter located in the southern part of the Massif Central (France). A taphonomic and sedimentologic study carried out in this area allows a reconstruction of Late Carboniferous vegetation in an intramontane context. The paleoecology of such limnic settings is poorly known, and this study permits detailed comparison with paralic basins for the first time. The Graissessac peat mires developed in abandoned fluvial channels, in floodplains, and above distal alluvial fans. The vegetation was dominated by monospecific stands of the arborescent lycopsid Sigillaria brardii, whereas the tree fern Psaronius occurred during the later stages of mire accretion. This is in contrast to coeval North American peat mires, which generally were dominated by tree ferns and pteridosperms throughout the mire profile. Stephanian floodplains and distal alluvial fans of the Graissessac-Lodève Basin were devoid of vegetation, with the exception of isolated thickets of sphenopsids that were composed of Calamites and Sphenophyllum. These plants were found growing in situ in the floodplain mudstones as well as in fine-grained sands of secondary channels. Parautochthonous foliage assemblages of ferns and pteridosperms found in floodplain mudstones represent the most diverse plant community. The plants supplying these remains were growing in exposed areas close to floodplains. Large logs attributed to cordaitaleans and monotypic assemblages of large Cordaites leaves were found in fluvial sediments, and suggest that the plants were riparian elements in the basin.

A new permineralized fossil plant assemblage is described from volcaniclastic tuff collected in the Upper Permian (Wuchiapigian to Changhsingian) Xuanwei Formation at Shanjiaoshu mine, Guizhou Province, China. The assemblage is fragmentary but contains a small sphenopsid strobilus, a partial strobilus of a lepidodendralean lycopsid, pinnae of the filicalean fern Anachoropteris and a filicalean non-laminate fertile pinna rachis, the marattialean ferns Eoangiopteris, Scolecopteris and Psaronius, hooked stems of probable gigantopterid affinity, and two kinds of cardiocarpalean ovules. This represents the first indisputable evidence of Anachoropteris from the Permian of China, and contrasts with previous evidence from Europe and North America that indicates this genus became extinct during earliest Permian times. The assemblage highlights the persistence of plants from wetland communities and mire ecosystems into the Upper Permian of southern China, and adds further support to the presence of the Ameriosinian phytogeographical realm. This represents the first record of a plant assemblage preserved in volcaniclastic sediments from the Upper Permian of southern China, and in combination with other recently discovered plant assemblages in similar deposits in southern China, suggests volcanism to be an important factor in facilitating permineralized plant preservation in this realm. Although the source of the volcanism that produced the tuff is unknown, its age and location are consistent with the Emishan Large Igneous Province (LIP) of southwest China.

Permineralized samples of the tree fern Psaronius sp. belong to the spectacular discoveries of the Lower Permian Rotliegend ‘Petrified forest of Chemnitz’, one of the most famous palaeontological sites in the world. The cellular tissues of the 280 million years old fossil fern show a delicate three-dimensional preservation by permineralization. Moreover, anatomical detail can be distinguished very well because of the black coloured former cell walls. By means of Raman spectroscopy this fossilised tissue of the adventitious roots is revealed to be carbon which structure seems to correspond to anthracite. The aim of this work is the experimental confirmation of the carbon structure by means of thermogravimetry and Raman spectroscopy on coal samples of different rank, especially anthracite samples from different times and localities. Coal maturation involves the sequence peat–lignite–coal–anthracite-microcrystalline graphite by incresasing the density and specific energy. The loss of in situ moisture (typically up to 200 °C) and volatile organic matter (up to 600 °C) has been acquired by thermogravimetry. The increasing carbon content, density resp. structure results in Raman spectra with typical band shape of the D- and G-peaks. We used these methods to characterise and compare the separated coal samples to the dispersed carbon inclusions in permineralized Psaronius.

New specimens of Botryopteris Renault deriving from the Permian of the Maranhao Basin (NE Brazil) are both the first evidence of this palaeozoic fern group from the Southern Hemisphere and the youngest known to date. These remains cannot be assigned to any known species of the Botryopteridaceae. Therefore, the new species Botryopteris nollii sp. nov. is established. One of the most conspicuous characters of this new fern is the ability to grow in different forms. Firstly, it has been found rooted within the marginal trunk base of the tree ferns Grammatopteris freitasii Rosler and Galtier and Psaronius brasiliensis Brongniart. Secondly, cauline organs, foliar members and adventitious roots of this fern formed a compound system of a so-called false trunk. This results from the formation of closely spaced spirally arranged foliar members of different order on upright stems and of the repetitive development of shoots from foliar-borne buds inside the trunk. The newly collected material is preserved as silicified permineralisation, and therefore allows to recognise characters of vegetative morphology but also details of the anatomy and internal organisation. Botryopteris nollii sp. nov. is characterised by nearly circular protostelic stems and stipes/rachises that show a dorsiventral ω-shaped vasculature. The new fern underlines the striking growth form diversity seen in the whole family Botryopteridaceae.

Coal balls were collected from four coal beds in the southeastern part of the Illinois Basin. Collections were made from the Springfield, Herrin, and Baker coals in western Kentucky, and from the Danville Coal in southwestern Indiana. These four coal beds are among the principal mineable coals of the Illinois Basin and belong to the Carbondale and Shelburn Formations of late Middle Pennsylvanian age. Vegetational composition was analyzed quantitatively. Coal-ball samples from the Springfield, Herrin, and Baker are dominated by the lycopsid tree Lepidophloios, with lesser numbers of Psaronius tree ferns, medullosan pteridosperms, and the lycopsid trees Synchysidendron and Diaphorodendron. This vegetation is similar to that found in the Springfield and Herrin coals elsewhere in the Illinois Basin, as reported in previous studies. The Danville coal sample, which is considerably smaller than the others, is dominated by Psaronius with the lycopsids Sigillaria and Synchysidendron as subdominants. Coal balls from the Springfield coal were collected in zones directly from the coal bed and their zone-by-zone composition indicates three to four distinct plant assemblages. The other coals were analyzed as whole-seam random samples, averaging the landscape composition of the parent mire environments. This analysis indicates that these coals, separated from each other by marine and terrestrial-clastic deposits, have essentially the same floristic composition and, thus, appear to represent a common species pool that persisted throughout the late Middle Pennsylvanian, despite changes in baselevel and climate attendant the glacial–interglacial cyclicity of the Pennsylvanian ice age. Patterns of species abundance and diversity are much the same for the Springfield, Herrin, and Baker, although each coal, both in the local area sampled, and regionally, has its own paleobotanical peculiarities. Despite minor differences, these coals indicate a high degree of recurrence of assemblage and landscape organization. The Danville departs dramatically from the dominance–diversity composition of the older coals, presaging patterns of tree–fern and Sigillaria dominance of Late Pennsylvanian coals of the eastern United States, but, nonetheless, built on a species pool shared with the older coals.

Samples of the permineralized tree fern Psaronius sp. from the Lower Permian Rotliegend of Chemnitz were examined to find out their chemical composition and structural behavior. The inhomogenic distribution of elementary constituents of oxides, sulfates and carbonates within the silica-matrix consisting of α-quartz and chalcedony were formerly detected by analytical X-ray microscopy. Most of the compounds could be revealed by Raman spectroscopy. Calcite and barite developed in small fissures. Iron of different oxidation level is the prevailing pigment in the agate preserved adventitious roots. Coalified cellulose whose structure mainly corresponds to anthracite reflects the anatomical detail of the former organic tissues.

290 Million years old petrifactions from the Lower Permian Rotliegend of Chemnitz were examined by analytical X-ray microscopy to determine their chemical composition. Mappings show the inhomogeneous distribution of the involved elements, which may reflect the former plant anatomy, as well as some contemporaneous processes of permineralization (with silica and fluorite) and agate-formation. Most prominent advantages of the analytical X-ray microscopy are the low preparation expense of the museum samples, the analysis scanning range and the X-ray spot diameter suitable with the dimension of the fossil plants.

Stimulated by new observations, this contribution presents a summary of the current knowledge of different plants that grew closely associated with Psaronius trunks in the Early Permian petrified forest of Chemnitz (Saxony, Germany). The role of Psaronius tree ferns was to provide a frequently-used substrate for colonisation by other plants. The massive root mantles protected different developing plants, and they may have improved the possibility of preservation of smaller plants and plant organs in particular. These are climbing axes of the fern Ankyropteris brongniartii , small epiphytes of the fern Tubicaulis sp., different isolated petioles of the fern Anachoropteris , small ? Grammatopteris axes, roots of the pteridosperm Callistophyton , and Dadoxylon specimens representing Amyelon roots of Cordaites and conifer stems. Further, plant-animal interactions demonstrate the role of Psaronius as an ecosystem unto itself.

A permineralized flora was discovered in the Carriere du Lion, at Engihoul (southern margin of the Namur Synclinorium, Belgium). This flora is preserved in dolomitic nodules within ampelitic alum shale. The goniatites Isohomoceras subglobosum and Homoceras beyrichianum allow this shale to be correlated with the Chokierian (Namurian A — Silesian — Carboniferous). The plant association includes Dubiocarpon elegans (Endogonales?), Lepidophloios sp., Lepidocarpon lomaxii (Lepidodendrales), Arthropitys sp. (Equisetales), Psaronius sp. (Marattiales), a group of sporangia incertae sedis, whose affinities are discussed, Myeloxylon sp. (Medullosales), and fragments of pycnoxylic secondary xylem. This flora is interesting because of its Namurian A age: the Arthropitys and Dubiocarpon specimens are the oldest known to date, and the Psaronius specimen is the oldest occurrence of a petrifaction of this genus.

An unusual liptinite coal component has been reported in the Chinese literature over the past sixty years. It has been described as a maceral in the Chinese National Standard (1991), but it has not been named internationally. In Chinese literature it is called “barkinite”, on the basis of its morphological features and because it is believed to have originated as bark tissue. “Barkinite” occurs in Late Permian, marine-influenced coals and is best represented in the Changguang, Leping and Shuicheng Basins of southern China. The material originates from plant periderm or the bark of higher plants. However, “bark” contains a variety of substances, including resin and suberin, which are recognised as the precursors of the resinite and suberinite macerals. “Barkinite” is distinguished by (i) its thickness; individual pieces can be more than ten cells thick and several centimetres long and (ii) it fluoresces strongly at 0.6% vitrinite reflectance and loses its fluorescence at about 1.1% vitrinite reflectance. The reporting of “barkinite” from only Chinese coals may be due to its origin from Lepidodendron and Psaronius flora, which was common in the Northern Hemisphere during the Carboniferous, but which was isolated to China by the Late Permian. It is proposed that the remnant flora evolved into unique forms in China by the Late Permian. Lepidodendron and Psaronius remains, coupled with a strongly marine-influenced, peat-forming environment have given rise to “barkinite” and to its restricted distribution.

International audience; A new species of permineralised marattialean fern trunk is described from Lopingian (late Permian) aged volcaniclastic tuffs from Panxian County, western Guizhou Province, China and named Psaronius xuii sp. nov. The stem has vascular bundles that are encircled by a bi-layered sheath and has a ground tissue consisting of thicker-walled and thinner-walled parenchymatous cells and dispersed nests of sclerenchymatous cells. Two sclerenchymatous strands occur between neighboring stelar cycles, with this species lacking a peripheral sclerenchyma sheath and possessing a "chrysanthemum"-shaped sclerenchyma strands in the adaxial bay of the peripheral vascular bundles. Although distinct from other species, comparisons demonstrate a consistent organisation amongst contemporaneous species from South Cathaysia that have sclerenchymatous strands in the adaxial bay of the peripheral vascular bundles, vascular bundles and leaf traces surrounded by a vascular bundle sheath, and the middle part of the leaf trace is depressed inward after departing from the peripheral vascular bundle. These features are used to define the Panxianensis Group named after the most comprehensively known species, P. panxianensis. Species within the Panxianensis Group differ from other species from the Carboniferous and Permian floras of Euramerica, Gondwana and North Cathaysia that we place in the Blicklei Group that lack sclerenchymatous strands in the adaxial bay of the peripheral vascular bundles, lack vascular bundle sheaths, and the middle part of the leaf trace is arched outwards when they depart from the peripheral vascular bundles. Members of the Panxianensis Group appear to represent a relatively derived group that appears to be endemic to South Cathaysia, with these presumably evolving from members of the Blicklei Group in the Cisuralian or Guadalupian

Although the prevalence or even occurrence of insect herbivory during the Late Carboniferous (Pennsylvanian) has been questioned, we present the earliest-known ecologic evidence showing that by Late Pennsylvanian times (302 million years ago) a larva of the Holometabola was galling the internal tissue of Psaronius tree-fern fronds. Several diagnostic cellular and histological features of these petiole galls have been preserved in exquisite detail, including an excavated axial lumen filled with fecal pellets and comminuted frass, plant-produced response tissue surrounding the lumen, and specificity by the larval herbivore for a particular host species and tissue type. Whereas most suggestions over-whelmingly support the evolution of such intimate and reciprocal plant-insect interactions 175 million years later, we provide documentation that before the demise of Pennsylvanian age coal-swamp forests, a highly stereotyped life cycle was already established between an insect that was consuming internal plant tissue and a vascular plant host responding to that herbivory. This and related discoveries of insect herbivore consumption of Psaronius tissues indicate that modern-style herbivores were established in Late Pennsylvanian coal-swamp forests.

We document the presence of the piercing-and-sucking functional feeding group and the dietary targeting of vascular tissue (phloem and xylem) in marattialean tree-fern rhachises from a Late Pennsylvanian (302 Ma) coal-swamp forest in the Illinois Basin. Our evidence originates from permineralized peat that exhibits cellular-level preservation of tissues from whole Psaronius tree-fern rhachises; it includes 3 stylet probes, each of which traverses epidermal tissues and parenchyma, and terminates in a distinctive feeding cavity within phloem and xylem of a vascular strand. The stylet probes are lined with an opaque, sheathlike material, and are principally intracellular, although large gum sac cells are avoided. One of their most diagnostic features is 1 or 2 ridges occurring on the inner surface of each stylet probe, paralleling most of the probe length. These ridges, documented by light and scanning electron microscopy, are interpreted as host tissue casts of interstyletal sulci. From these and other features of stylet-trace morphology, we conclude that the herbivore was an insect of the order Palaeodictyoptera rather than an hemipteroid insect. Well developed reaction tissue surrounding the stylet trace developed while the plant host was alive, demonstrating herbivory. Previous studies have documented piercing-and-sucking in several examples of plant damage from the Early Devonian to Late Pennsylvanian (395–290 Ma). The oldest credible examples are plant lesions indicating piercing-and-sucking arthropods from 2 Lower Devonian deposits. We hypothesize that in later Middle Pennsylvanian, equatorial, coal-swamp forests of Euramerica, the dominant arborescent plants possessed vascular tissues largely unavailable to insects, because they were either deeply embedded in thick cortical tissues or protected by outer indurated, peridermal tissues. Subsequent tree-fern forests of the Late Pennsylvanian provided accessible vascular and other tissues to surface-dwelling insects with stylate mouthparts–a condition which continued into the Permian and propelled the hemipteroid radiation.

An outcrop of the Duquesne Coal (Conemaugh Cyclothem) has the only significant occurrence of coal balls in Upper Pennsylvanian (Stephanian B equivalent) sediments of the Appalachian Basin. Excellent preservation of plant debris within autochthonous peat has permitted a more refined reconstruction of the source plant community than reported in published studies of other coals. Coal balls were quantitatively sampled for whole-plant species and mineralogical content. Shoot-root ratios were extremely high compared with values reported for other coals. The samples were analyzed using cluster analyses and non-metric multidimensional scaling (MDS) in order to differentiate microhabitats and stages of ecological succession within the general flora. Cluster analysis produced 5 stable clusters, which agreed with the sequence of ecological succession as determined in a previous study, and with microhabitat differentiation in contemporaneous seral stages. Three dimensions of the MDS analysis provided the best fit to the data. The dimensions are interpreted as representing: (1) ecological time or succession; (2) increasing dominance of Psaronius tree ferns in the plant community; and (3) an increase in microtopological variation (probably hummock formation). The initial stages of succession (oldest layers of permineralized peat) are characterized by aerial debris from Mesoxylon, Sigillaria and Calamites, followed by an assemblage dominated by Chaloneria. This was succeeded by more species diverse assemblage, dominated by Neuropteris seed ferns and Psaronius tree ferns, with numerous subcanopy plants, including lianas, epiphytes and ground herbs. Late seral stages (youngest layers of permineralized peat) were dominated by Psaronius tree ferns.

The dominant plants of the Late Carboniferous lowland tropics were taxonomically and structurally distinct from those of any later time periods. Dominance was distributed among lycopsids, ferns, sphenopsids, pteridosperms and cordaites, and each of these groups had distinctive and different ecological preferences and amplitudes. Peat-forming habitats were dominated by lycopsids throughout the Westphalian, with a significant cordaitean element in the middle Westphalian; during the Stephanian tree ferns were dominant, following major extinctions near the Westphalian-Stephanian transition. Each of the major plant groups had distinctive architectures and tissue composition. Trees contributed up to 95% of the peat biomass and tree forms of lycopsids. Psaronius and Medullosa lack good modern analogues. The cordaites were the only woody plant group to contribute significantly to peat, and then only during the mid-Westphalian. Structurally wood-like lycopsid bark is the major “woody” tissue encountered in most Westphalian coals. Tree ferns and pteridosperms were largely parenchymatous in construction; the stigmarian root systems of lycopsids also were largely parenchymatous. The tissue structure of these dominant plant suggests the need for extreme caution in the inference of mire ecological conditions or vegetational structure from coal petrographic data. Peat formed under arborescent ferns or pteridosperms, or peat repeatedly exposed to decay and rerooting by stigmarian root systems of lycopsids, would have a distinctly non-woody signature and yet would have formed in a forested environment. A summary is presented of the autecology and synecology of mire plants, emphazing the structural framework provided by lycopsids during the Westphalian. Certain constraints in the links between peat biomass and miospore palynology are discussed in terms of over-representation, under-representation and non-representation. The formulation of Smith's four-phase hydroseral model is discussed and compared with more recent data available from plant paleoecology. The current debate over an ombrotrophic vs. rheotrophic origin of Late Carboniferous peats relies in large part on paleobotanical data, almost entirely palynological, in combination with petrographic analyses. Ecological studies of miospores and of coal-ball and compression macrofossils, and the linkage of miospores to source plants, permit the re-evaluation of mire successional models. Evidence for tree lycopsids, sphenopsids, pteridosperms and cordaites suggests growth mainly in rheotrophic mires. Tree ferns are likely candidates for growth in domed mires, although evidence is ambiguous and some tree ferns clearly grew under rheotrophic conditions. Densospores, produced by at least Sporangiostrobus lycopsid subtrees, have been considered diagnostic of ombrotrophic conditions; abundant evidence refutes this simplistic interpretation and suggests broad ecological amplitudes for densospore producers, including growth under rheotrophic conditions. Although plant fossils alone can not resolve most of the major debates in modern coal geology, paleobotany does contribute significantly to our understanding of ancient mires. An approach combining paleobotanical data with petrography, sedimentology and geochemistry, on a case by case basis, is most likely to produce a clear picture.

Silica permineralized stem fragments from six municipalities of São Paulo, Brazil, belonging to the Passa Dois Group, Corumbataí Formation (Guadalupian, Permian), were analysed. Morpho-anatomic characteristics of the stems and steles, observed on petrographic slides or polished sections, have permitted the classification of many specimens as Tietea cf. Tietea singularis. A stem piece from the region of Casa Branca, determined as Psaronius cf. Psaronius arrojadoi, corresponds to the first true record of this genus in the Paraná Basin. A generic/specific identification was not possible for radicular mantle samples having no preserved steles. Despite the strong influence of taphonomic factors on the record, all known Marattiales fossils from the Paraná Basin in Brazil present relatively small steles and meristeles, and that may be related to hydric stress. Taphonomic, paleoecological and biogeographical aspects of the analysed fossils are discussed as well., Foram analisados fragmentos de caules permineralizados por sílica de filicíneas arborescentes, procedentes de seis municípios do estado de São Paulo, pertencentes ao Grupo Passa Dois, Formação Corumbataí (Guadalupiano, Permiano). Características morfo-anatômicas principalmente dos estelos, observadas em lâminas petrográficas e/ou superfícies polidas dos caules, contribuíram na classificação de diversos exemplares como Tietea cf. Tietea singularis. Um exemplar de Casa Branca, determinado como Psaronius cf. Psaronius arrojadoi, corresponde ao primeiro registro seguro do gênero para a Bacia do Paraná. Não foi possível a identificação genérica/específica das amostras que apresentam apenas os mantos radiculares preservados. Ainda que os fatores tafonômicos tenham influenciado no registro fossilífero, todos os fósseis conhecidos de Marattiales da Bacia do Paraná na porção brasileira exibem estelos e meristelos relativamente pequenos, o que pode sugerir estresse hídrico. São também discutidos aspectos tafonômicos, paleoecológicos e paleobiogeográficos dos fósseis analisados.

Psaronius sp. (Fig. 7A, B) Fragments of root mantle of Psaronius trunks are common elements; they occur in about half of the specimens either as portions of the inner root mantle (Fig. 7A) where the roots are cohesive with an interstitial tissue, or as isolated larger roots from the outer zone of the trunk (Fig. 7B) showing a characteristic aerenchymatous cortex and stellate xylem strand. In the absence of information on the stele of the stem a specific attribution is, however, impossible., Published as part of Galtier, Jean, Ronchi, Ausonio & Broutin, Jean, 2011, Early Permian silicified floras from the Perdasdefogu Basin (SE Sardinia): comparison and bio-chronostratigraphic correlation with the floras of the Autun Basin (Massif central, France), pp. 43-69 in Geodiversitas 33 (1) on page 56, DOI: 10.5252/g2011n1a4, http://zenodo.org/record/4596948

ACL-11-43; International audience; In the Perdasdefogu Basin (Ogliastra, Sardinia) plants occurring in angular cherts are preserved as siliceous permineralizations. The plant assemblage consists of the genera Sphenophyllum, Arthropitys, Astromyelon, Palaeostachya, Pecopteris, Scolecopteris, Stewartiopteris, Psaronius, Ankyropteris, Anachoropteris; furthermore, probable medullosan wood and ovules, cordaitean stems, leaves and ovules, and Dadoxylon wood have been recorded. Arborescent marratialean ferns are the dominant elements with Pecopteris and Scolecopteris leaves being the most common; the calamiteans are the second in abundance. Generally the chert blocks contain a large number of plant fragments -- roots and leaves are being almost equally represented -- suggestive of a coal ball-like plant accumulation. More rarely a chert block may consist of a single plant part, for example a piece of wood. The preservation and accumulation of the plants are closely comparable to the silicified plant assemblages described from the Lower Permian of Autun and the upper Pennsylvanian of Grand-Croix (Massif central, France) and from the Early Permian Döhlen Basin (Germany). It is certainly significant that the assemblage from the Perdasdefogu Basin is dominated by tree ferns and calamites like the coeval silicified vegetation from Autun. However, like in Autun, the permineralized flora contrasts with the underlying compression floras dominated by conifers and peltasperms. The Perdasdefogu macroflora record suggest a middle-upper Autunian age which corresponds to the Surmoulin and Millery formations of the Autun Basin. This is in agreement with the Asselian-Sakmarian transition as pointed out by the amphibian species found in the same formation, and perfectly correlatable with the same association found in Gottlob-lake (Thuringian Forest Basin). Because of its rich fossil content, the Perdasdefogu Basin represents a reference succession for the Autunian of the entire westernmost palaeo-Tethyan domain and its macrofloral record

ACL-11-04; International audience; Psaronius housuoensis sp. nov. is described from the Upper Permian Xuanwei Formation deposits of Housuo Coal Mine, Fuyuan County, Yunnan Province, southwest China, adding to the marattialean fern community of the Cathaysian flora. The permineralized stem shows a polycyclic dictyostele with five leaf traces arranged in a helical manner and exhibiting 2/5 phyllotaxy. Vascular bundles arranged in 6 concentric rings with cauline bundles in 5 radial rows. Stem bound externally by a peripheral sclerenchyma sheath. Leaf trace configuration comprised of three vascular bundles resulting from the division of a single originally C-shaped strand. Ground tissue replaced with coprolites and sediments. Stem surrounded by a thick mantle of roots. Occurrence of coprolites within the stem indicates well developed plant-animal interaction during the Late Permian times and that the habitat in which Psaronius grew was abounding with diversity of arthropod or the oribatid mite community preferring the rotting P. housuoensis sp. nov. stem ground tissue as a suitable microenvironment for shelter. Evolutionary pattern of leaf trace development is described in the new species and its possible ecological significance.