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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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 944×1190μm to 1065×1120μm, 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. [Copyright &y& Elsevier]

Abstract: 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. [ABSTRACT FROM AUTHOR]

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 ϙ-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, in which secretory cavities are dispersed. Bound roots mostly possess seven to nine protoxylem poles. The vascular bundle sheath is one or two cell layers thick. The inner cortex consists of aerenchymatous parenchyma. A detailed comparison of the present specimen with known species of Psaronius from the Permian of South China is made. Our specimen is similar to Psaronius wangii in many aspects, but the two can be clearly distinguished by the structure of the ground tissue of the stem and the leaf base vascular configuration, which leads to the erection of a new species, P. laowujiensis, for this specimen. Certain important characters in species from the Permian of South China are discussed. The tree- or anchor-shaped sclerenchymatous configuration within the centripetal concavity of the peripheral cauline bundles is unique to species from the South China Permian. The permanent vascular bundle sheath surrounding the meristeles of the stem and the stele of the root is another remarkable feature of those species. The analogous tissue, termed "inner cortex" by certain authors, is also present in some Psaronius from the Euramerican and North China floras, but in those cases it is thinner walled and not as remarkable as the vascular bundle sheath in the species from South China. The leaf base vascular configuration of the species from the Permian in South China is more diverse than those from other places. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [Copyright &y& Elsevier]

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. • Permineralized and impression/compression psaroniaceous stems are described from Wuda Tuff Flora. • Impression/compression stems (Caulopteris) show a high diversity (8 species, including 3 new ones). • Permineralized stems (Psaronius) have a lower diversity (3 species), which is probably caused by 4 factors. [ABSTRACT FROM AUTHOR]