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International audience; One of the youngest occurrences of anatomically preserved Sphenophyllum Brongn. 1828 is reported from the Permian Motuca Formation, Parnaíba Basin, central-north Brazil. At least 31 stems of this extinct sphenophyte, which are densely interwoven with each other and associated with tiny roots and leaves, occur in a silicified state within the pith of a stem of the arborescent calamitalean Arthropitys barthelii, which was additionally bored by putative xylophagous herbivores. Although restricted within natural limits, the Sphenophyllum plants show different developmental stages that encompass mostly juvenile stems but also a few with initial secondary growth. The stems are circular to elliptical in outline and consist of a central triarch actinostele made of primary vascular tissues and a variable amount of wood. Extraxylary tissues comprise a narrow innermost zone with putative phloem, internal periderm of rectangular cells arranged in radial files, inner parenchymatous cortex, outer sclerenchymatous cortex, and small-celled layers of bounding tissue. Furthermore, Sphenophyllum plants are frequently found as climbers on the trunk surfaces of Psaronius Tietea and Grammatopteris tree ferns, or they are trapped among the adventitious aerial roots of these plants. In addition, Sphenophyllum cauline members were also found dispersed with other plant organs in a particular type of fossil-rich, silicified fluvial sandstone or chert, reflecting rapid fossilisation of parautochthonous remains. The presented fossil assemblages provide evidence of a previously underestimated facet of the ecosystem in seasonally influenced, densely vegetated riparian forests bordering extended distal fluvial discharges in low-latitude Gondwana. Because of largely similar development of major anatomical traits in these late Paleozoic sphenophylls, taxonomic delimitation based on vegetative axes alone remains challenging and highlights the unexpectedly long-term stability of the primary cauline anatomy in particular and vascular architecture in general. As a result, the studied Brazilian specimens can only be identified as Sphenophyllum sp., although we emphasise close relationships to Sphenophyllum thonii, a nearly worldwide distributed species during the early Permian.

International audience; The medullosans represent a diverse group of pteridosperms that was widely distributed in forested landscapes of the late Paleozoic. These plants became widely known from the extensive tropical lowland basins of Euramerica, where they grew as slender plants with large fronds and fern-like foliage. Besides, there also exist medullosans of Late Pennsylvanian–early Permian intramontane basins of Central Europe, which have been out of research focus for more than a century. They had bigger stems with larger amounts of secondary xylem and a modified organisation of the vascular system. We provide an overview on taxonomy, anatomy and palaeoecology of these medullosans from the most important fossil localities, encompassing Chemnitz (Germany), the type locality for most taxa, Autun (France), Nová Paka (Czech Republic) and others. Late Pennsylvanian–early Permian medullosans of intramontane basins were thriving under seasonally-dry palaeoclimate on wet clastic soils showing proximity to the groundwater level. In forested landscapes, they occurred mostly sub-ordinated as part of the forest understorey. The plants' architecture and taphonomical inferences point to a (semi-)self-supporting growth habit of most of the taxa presented here. Plant architectural and anatomical peculiarities suggest a high water-conducting potential of these plants, raising questions on their ecological role in early Permian habitats. Anatomical differences with tropical relatives of Carboniferous age might reflect an evolutionary process that was driven by environmental changes during the late Paleozoic. The unusual arrangement of their stem tissues addresses the question of their role in seed plant evolution, e.g., their potential relationship with cycads.

International audience; The Late Pennsylvanian deposits of the Graissessac Basin (southern France) are well known for their abundant and diversified plant remains. Here we report on seven trackways of giant millipede-like arthropods recently discovered from two surfaces. These traces are ascribed to Diplichnites cuithensis. The trackways are up to 200 cm long, up to 36 cm wide, straight to curved and consist of two parallel rows of numerous and elongated appendage imprints that are oriented perpendicular to the midline. Although body fossils of giant millipede-like arthropods remain unknown in sediments from this basin, the morphology and size of the trace fossils indicate that the trails were made by 0.9 to 1.6 m long individuals of Arthropleura. The depositional environment is interpreted as a regularly inundated floodplain close to a fluvial channel and dominated by lycopsids. Such a vegetation was probably an attractive and important source of food for the giant herbivorous arthropods that were roaming the riparian landscapes of the Graissessac Basin. This new occurrence of Arthropleura trackways confirms that this giant arthropod was a common member of Late Palaeozoic continental biotas.

International audience; We describe a new species of the Paleozoic fern genus Botryopteris in volcanic tuffs from the Lopingian (upper Permian) aged Junlian Formation in SW China's Sichuan Province. The species has a large stem and stele compared to those of some other species of the genus. Xylem strands of the leaf trace and rachis are “ω”-shaped in cross section and comprise two long lateral arms and a single, shorter median arm. Parenchyma is distributed among the stem metaxylem tracheids and is more common in the central region of the stele that comprises a parenchymatized protostele. Several mesarch protoxylem strands, decurrent from leaf traces, are visible in each cross section of the protostele. Root traces originate from the lateral side of the leaf trace within the stem cortex. The stem surface is covered by thick, multiseriate, multicellular trichomes. Botryopteris multifolia sp. nov. represents the stratigraphically youngest known species of the genus and has a combination of derived evolutionary characteristics including its large stem size, parenchymatized protostele, elaborate trichome structure, roots originating from leaf traces, and the construction of xylem strand of the leaf trace and rachis with distinctive pinna trace formation and emission. It is more similar in leaf anatomy to the Gondwanan species B. nollii from the Permian of Brazil and less like late Pennsylvanian botryopterids from Euramerica. Finally, we consider the evolutionary implications of features shared between Permian members of the botryopterids and catenalean-type plants including members of the Osmundales stem group family Guaireaceae (Shuichengella, Zhongmingella, Tiania) and the enigmatic early ferns Rastropteris and Catenopteris.

The late Paleozoic ice age (LPIA) constitutes a unique framework in which to study deep time plant-climate interactions. Key research foci include (1) the onset of the first ice age on a vegetated planet and elucidating the role that plants played in this global cooling, (2) plant evolution and dynamics during LPIA glacial-interglacial oscillations, which have been compared to those of the Cenozoic, and (3) the establishment of polar forests with no extant equivalent as high latitudes became unglaciated in the Permian. The purpose of this talk is to present an overview of these major research topics and use the tropical floras from the Pennsylvanian and Permian of the Graissessac-Lodeve region in southern France as a case study of plant dynamics during the LPIA. The Graissessac basin contains one of the best-preserved examples of intramontane Late Pennsylvanian wetlands in southern Europe. Plant-yielding deposits have been extensively studied since the 19th century and document the vegetation of alluvial fans, fluvial channels, floodplains, and peat mires. Stands of arborescent lycopsids (Sigillaria) dominated the peat mires, while tree ferns (Psaronius), sphenopsids (Calamites, Sphenophyllum), and medullosan pteridosperms occupied different zones of the floodplains. Allochtonous logs and leaves of cordaitalean gymnosperms reflect the vegetation of higher/drier areas of the landscape. This vegetation contrasts with that of coeval coastal (paralic) wetlands from North America, which had a different spatial distribution of taxa. Permian deposits from the nearby Lodeve basin record a change towards increasingly drier conditions. The oldest macroflora in the basin is one of the most diverse Asselian plant assemblage known to date, with over 40 species. While some of the plants correspond to Carboniferous taxa that persisted in the early Permian, the flora is dominated by conifers, indicating a more seasonal and arid climate. It also contains an important diversity of peltaspermales (pteridosperms), as well as some occurrences of ginkgophytes and cycadophytes that started diversifying at that time. Younger assemblages from the basin are also dominated by conifers and other seed plants and reflect a transition to semi-arid conditions by the end of the early Permian (Artinskian-Kungurian).

International audience; Premise of research : Mississippian (Lower Carboniferous) anatomically preserved ovules are pivotal to our present understanding of the Paleozoic primary seed plant radiation, but few are known from the late Viséan stratigraphic interval approximately 330 million years ago. Here, we document an exceptionally well-preserved mesoscopic charcoalified ovule from late Viséan limestones that is adapted for wind dispersal and for deterring herbivory.Methodology : We use synchrotron radiation X-ray tomographic microscopy (SRXTM) and low-vacuum scanning electron microscopy (LVSEM) to analyze histological features not identifiable through traditional methods.Pivotal results:The ovule is small, 2 mm long and 1.25 mm in maximum diameter, and has a dense covering of spirally arranged, long, slender, hollow hairs with glandular apexes and a distal papilla. The nucellus is fused to the integument up to the nucellar apex, and above this, the integument comprises eight apical lobes, each with a single vascular bundle. The nucellar apex has a domed pollen chamber and large central column characteristic of hydrasperman-type (lagenostomalean) pteridosperms, but it lacks the distal salpinx seen in most hydrasperman ovules, leaving an exposed distal opening to the pollen chamber for pollination. Differences with existing taxa lead to the erection of Hirsutisperma rothwellii gen. et sp. nov.Conclusions : The apical glands presumably functioned as granivory deterrents; coprolites (fossilized feces) from herbivorous arthropods are abundant in the fossiliferous horizon and at this stratigraphic interval. The small ovule size and its dense covering of hairs indicate Hirsutisperma was adapted for wind dispersal and was an r-selected species, producing large numbers of small offspring in unstable or changing environments. Taphonomic implications are discussed, including preservational biases for charcoalification. Hirsutisperma provides the first clear evidence for ecological niche partitioning in Mississippian hydrasperman-type ovules.

Agora Paleobotanica (Congrès, Montpellier, du 10 au 12 juillet 2017); International audience; Documented evidence of fungi associated with Mesozoic ferns is exceedingly rare. Three different types of fungal remains occur in a portion of a small, permineralised fern stem of uncertain systematic affinities from the Triassic of Germany. Exquisite preservation of all internal tissues made it possible to map the spatial distribution of the fungi in several longitudinal and transverse sections. Narrow, intracellular hyphae extend through the entire cortex, while wide hyphae are concentrated in the cortical intercellular system adjacent to the stele and leaf traces. Hyphal swellings occur in the phloem and adjacent cortex, while moniliform hyphae (or chains of conidia) are present exclusively in parenchyma adjacent to the stele. No host response is recognisable, but host tissue preservation suggests that the fern was alive during fungal colonisation. The highest concentration of fungal remains occurs close to the stele and leaf traces, suggesting that the fungi either utilised the vascular tissues as an infection/colonisation pathway or extracted nutrients from these tissues. This study presents the first depiction of fungal distribution throughout a larger portion of a fossil plant. Although distribution maps are useful tools in assessing fungal associations in relatively small, fossil plants, preparing similar maps for larger and more complex fossils would certainly be difficult and extremely arduous.

International audience; Combresomyces cornifer is a conspicuous spheroidal microfossil (

Fern fossils from the Triassic are predominantly impressions and compressions; structurally preserved specimens are comparatively rare and primarily known from the Southern Hemisphere. Several permineralized stem portions from the Triassic of Upper Silesia are assigned to the poorly known genus Knorripteris (Knorripteridaceae), an enigmatic taxon initially attributed to the lycopsids but later reinterpreted as belonging to the ferns. Because the new stems differ from the known species of Knorripteris, they are assigned to a new species, for which the name Knorripteris taylorii nov. sp. is proposed. K. taylorii is characterized by a discontinuous phloem cylinder, leaf trace xylem strands that continue down to and converge at the center of the stem, cells with spiral thickenings (i.e., transfusion tissue) accumulating within the central zone of the stem, and xylem strands with abaxial protoxylem. Knorripteris exhibits several major features not typically seen in ferns, including a stelar organization that does not conform to the protostele/siphonostele/dictyostele types traditionally recognized in fossil and living ferns, the abaxial versus adaxial orientation of the protoxylem in leaf traces, as well as the acropetal decrease versus increase of the xylem in the leaf trace. The vascular system of Knorripteris is unique and challenges current concepts with regard to stelar evolution in ferns. The discontinuous phloem cylinder shows a cauline dictyostelic aspect, while the xylem appears to be foliar in origin. Knorripteris lacks a central protostelic column of vascular tissue; rather, the small foliar xylem strands come into close contact, but there is no evidence of fusion of tracheid bundles. Despite the wealth of new information on the internal organization of the Knorripteris stem provided by the specimens described in this study, the position of Knorripteris and the Knorripteridaceae within the ferns remains elusive.

International audience; A new taxon of lignophyte is described based on a permineralized stem from the Late Tournaisian (Lower Carboniferous) of the Central Ahnet region, Algeria. It shows similarities with arborescent seed plants described in the Lower Carboniferous of Europe and North America such as Eristophyton waltonii Lacey and Cauloxylon ambiguum Cribbs. However, the primary and secondary vascular system of the stem display an original combination of characters and it is assigned to a new genus: Ahnetia. The preservation of extraxylary tissues (secondary phloem, periderm, cortex) allows formulating hypotheses on the stem's growth potential. The early appearance of a periderm indicates that Ahnetia was capable of significant secondary growth and that the specimen likely represents a young axis of a larger plant. By its Late Tournaisian age, this specimen represents the oldest known occurrence in North Africa of a lignophyte capable of significant secondary growth after the extinction of the progymnosperm Archaeopteris.

We review progress made during the last 25 years in our understanding of the Protopityales, Early Carboniferous plants belonging to the extinct group of the progymnosperms. Recent studies support p...

International audience; Trigonotarbids and scorpions (Arachnida: Trigonotarbida, Scorpiones) are described from the Upper Carboniferous (Late Stephanian/Late Gzehlian) of the Graissessac Basin in the Central Massif outcropping in southern France. This is the first record of trigonotarbids and the first thorough description of scorpions from this locality. Trigonotarbids are an extinct order and the new fossils express a distinctly ornamented dorsal surface and lobed carapaces implicit of the so-called ‘eophrynid-assemblage’; probably a derived clade. Although closest to Eophrynidae, the character combination preserved precludes unequivocal assignment to any of the currently recognized families, but appears to be unique among trigonotarbids and prompts us to propose the name Aenigmatarbus rasteli gen. et sp. nov. to accommodate these novel specimens. The Graissessac scorpions are preserved in dorsal view only, but two distinct morphotypes could be recognized. These are tentatively referred to here as two typical Coal Measures genera: namely the mesoscorpion Eoscorpius sp. and the more derived orthostern Compsoscorpius sp., respectively.

ACL-12-01; International audience; A distinctive fungal endophyte, Cashhickia acuminata nov. gen. et sp., is described from permineralized calamite roots from the Upper Pennsylvanian Grand-Croix cherts of France. Heavily infected roots contain numerous intracellular hyphae in the outer cortex that arise from a meshwork-like mycelium extending between cortical cells. All intracellular hyphae are oriented toward the root center; none occur on the inner periclinal host cell walls. Other roots of the same type show localized infection by this fungus in which isolated cortical cells contain or give rise to intracellular fungal growth. Within the cortical cells are host responses in the form of callosities that indicate the roots were alive at the time of infection. Other endophytes are present in the same host tissue but are less frequent. The discovery of this association provides the first detailed account on the morphology of a Carboniferous fungal root endophyte, as well as the spatial distribution within the host, and infection pathways within the cortical tissues.

A middle Tournaisian flora comprising several taxa of arborescent lignophytes is documented for the first time in Australia. It challenges earlier hypotheses considering that the early Mississippian vegetation of Australia was impoverished and dominated by small to medium sized arborescent lycopsids until the Serpukhovian when climatic conditions became favorable to the thriving of the famous lignophyte-dominated “ Rhacopteris flora” recorded in Australia but also South America. The present account is based on anatomically preserved fragments of trunks and branches from two localities of Queensland, in the Broken River Province and the Burdekin Basin. Three taxa are recognized, Dameria hueberi gen. et sp. nov., the putative progymnosperm species Protopitys buchiana Goeppert 1850, and a taxon of uncertain affinities characterized by a Pitus type of wood but which differs from the latter genus by anatomical traits relative to its primary body. The possible occurrence of subtle growth rings in some of the woods from the Burdekin Basin and the conifer like traits of the Dameria wood are interpreted as ecological clues suggesting that these trees may have inhabited drier settings than the wetland habitats generally inferred for the lycopsids. This difference in habitats is suggested to explain the rarity of arborescent lignophytes compared to lycopsids in the Australian record of plants of early Mississippian age. The three taxa reported in this paper represent the earliest record of arborescent lignophytes in Australia after the global events that affected the vegetation at the Devonian–Carboniferous boundary and the extinction of Archaeopteris . They show that the successional pattern of arborescent lignophytes around the Devonian–Carboniferous boundary is comparable to that observed in Western Europe with the evidence of a diversification occurring as early as the middle Tournaisian. The palaeogeographic and stratigraphic distribution of Protopitys and Dameria indicates the occurrence of extensive floral exchanges between southern Laurussia and north-eastern Gondwana in the Late Devonian to Mississippian.

Ten different types of microproblematic structures occur on the surfaces, and in epidermal and hypodermal cells of fern pinnules preserved in the Late Pennsylvanian Grand-Croix cherts from France. These include thick-walled spheres, some with a prominent exit site, aggregations of variously sized spheres that may be surrounded by a membrane or sheath, a cylindrical structure composed of polygonal compartments, and branched hyphae/filaments with intercalary swellings protruding from a small opening in the surface (probably a stomatal pore). Some of the structures likely were produced by some fungal group, and may represent (resting) spores, microsclerotia, and conidiophores. The affinities of the others, and sometimes even their biological nature, remain difficult to determine. Nevertheless, documenting these structures is important because it provides the first indication for vascular plant leaves that were colonized by different types of organisms in a late Paleozoic ecosystem.

Four different morphotypes of microfungal remains occur in the partially degraded cortex of a specimen of Biscalitheca cf. musata (Zygopteridales) from the Upper Pennsylvanian Grand-Croix cherts (Saint-Etienne Basin, France). These include (1) clusters of spherical structures that appear to have developed within individual host cells; (2) relatively thick-walled spheres with one or two long, narrow protrusions; (3) spherical to pear-shaped structures in physical connection with tenuous, multi-branched filaments; and (4) pear-shaped structures with prominent surface projections. Structures resembling type (3) have also been found associated with the spores of B. cf. musata . Most of the organisms were probably saprotrophs based on the condition of the host. Although all of the fossils resemble chytrid zoosporangia, the systematic affinities of the microfungi in B. cf. musata remain equivocal because specific diagnostic features are absent. Nevertheless, the fossils provide a remarkably detailed account of the morphology of microfungi associated with land plants some 300 Ma ago.

Microscopy and Microanalysis, 15 (2), ISSN:1431-9276, ISSN:1435-8115

A new taxon of probable gymnosperm affinities is described from the base of the Carboniferous (Mississippian, Middle Tournaisian) of Montagne Noire, southern France. It is based on a permineralised stem showing vascular and cortical tissues, and one attached petiole base. Faironia difasciculata gen. et sp. nov. shows the combination of a broad eustele and dense wood with a multifascicular leaf trace, originating from two non-adjacent axial strands. The Kalymma -type petiole base resembles that of the calamopityan pteridosperms but anatomy of the stele, wood and phloem more closely compares to that of early arborescent gymnosperms such as Pitus , Eristophyton or Megalomyelon the taxonomic position of which needs to be re-evaluated. Faironia is the sixth genus of seed plant affinities based on stems reported from the Montagne Noire deposits that, to date, comprise the most diverse assemblage of permineralised seed plant remains from just above the Devonian/Carboniferous boundary.

A large permineralized calamitean stem, Arthropitys yunnanensis Tian et Gu from the Upper Permian of southwest China is reinvestigated and interpreted. The stem has a broad pith and well developed and large carinal canals. Secondary xylem is thick and characterized by wide parenchymatous interfascicular zones that remain constant in width throughout the wood. Striking features of the stem include the abundant leaf traces arranged in two whorls in the cortex with this arrangement previously unrecognized within calamitean stems, and the presence of growth rings in secondary xylem that suggest frequent fluctuations in environmental stress presumably due to variations in water availability. Features of A. yunnanensis infer the stem to be in the epidogenetical phase of calamitean development, and suggest it to be the basal part of a large trunk. Comparisons with biomechanical models for calamitean stems suggest this species had a semi-self supporting habit.

Sublagenicula nuda lycophyte megaspores from the upper Visean of central France frequently host a colonial green alga as an endophyte. This association was first recorded more than 100 years ago by the French paleobotanist B. Renault, who introduced the name Lageniastrum macrosporae for the alga. However, the biological significance of the discovery was not fully assessed until recently. The L. macrosporae–S. nuda association represents the oldest compelling fossil evidence for algal endophytes in land plants, and the only example to date of an alga residing in the interior of spores of vascular cryptogams. Here we present a detailed re-evaluation and photographic documentation of the surviving original specimens from the Visean of Combres/Lay and Esnost. Moreover, a newly discovered specimen from the Stephanian of central France represents the first record of this association from the Upper Carboniferous. An emended diagnosis for L. macrosporae Renault, 1896 is provided, and a lectotype and paralectotype are designated. Although L. macrosporae displays a striking suite of morphological characters found in members of the extant chlorophyte family Volvocaceae (especially the genus Volvox), the peculiar biology of the fossil necessitates establishment of a new family, for which the name Lageniastraceae is proposed. Considerations of the adaptive advantages for the alga of occupying the interior of megaspores are offered. These include the possible effectiveness of the spores in protection during periods of desiccation and against plankton-feeding animals, and use of the spores as potential vectors for dispersal from one isolated body of water to another by spore-feeding animals.

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.

The knowledge of fossil plant-insect interactions is almost entirely restricted to evidences of feeding behavior. Records of endophytic oviposition are relatively scarce, with previous earliest reports from the Middle to the early Late Triassic. Nevertheless, several Paleozoic insect taxa have been suspected of this reproductive behavior, but without any direct evidence. Specimens of Calamites cistii (Sphenophyta; Pennsylvanian, France) are described showing endophytic cavities, located in the outer cortex of the stem, a tissue that is rarely preserved. This new record shifts the appearance of this behavior back 60 Ma. Possible tracemakers are representatives of the Odonatoptera (Odonata and related extinct taxa), Palaeodictyopteroidea (extinct palaeopterous orders), and Archaeorthoptera (Orthoptera and related extinct orders). The antiquity of the insect endophytic oviposition behavior suggests that it could have been important during the emergence and diversification of the insect group.

Compression specimens of fern foliage, initially identified as Alloiopteris cf. quercifolia, have been collected from the Lower Carboniferous olistolitic flysch of the Montagne Noire, south France. Additional material comprising fertile pinnae in connection with vegetative pinnae justifies the attribution of the plant to the genus Corynepteris Baily. A new species, Corynepteris cabrierensis sp. nov., is established on the basis of distinctive sterile and fertile pinnule morphology, locally tripinnate organization of both vegetative and fertile pinnae, and proximal distribution of the sporangia within fertile pinnae. This fern had relatively large fronds with a robust erect main rachis or phyllophore (up to 15 mm diameter) bearing paired pinnae, a typical feature of zygopterid ferns. The generic diagnosis of Corynepteris is emended, and C. cabrierensis is reported as the oldest species presently known. In contrast, Alloiopteris erosa from the Upper Carboniferous Stephanian coal basin of Graissessac (south France) is one of the youngest known representatives of the same group of ferns. In the absence of fertile parts, the specimens have been attributed to the genus Alloiopteris; they exhibit the same organization including phyllophores bearing paired vegetative pinnae, but the frond is much smaller than in the older C. cabrierensis. Interestingly, A. erosa fronds are associated with axes bearing small dichotomous appendages, which are interpreted as their probable rhizomes and conform to the description of permineralized stems of Zygopteris. This should be the first record in compression material of Zygopteris stems bearing fronds of the Alloiopteris or Corynepteris type.

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.

Anatomically preserved calamitean stems are described from a previously unknown Late Permian locality in Sichuan Province, China, where they are preserved in volcaniclastic tuffs. Stems possess a large pith with secretory cells and pith cavity, and a narrow perimedullary zone. Primary xylem strands have poorly developed carinal canals whereas the secondary xylem is divided into parenchymatous interfascicular zones and fascicular wedges of tracheids and secondary rays, with the tracheids of the inner part of the secondary xylem having nearly the same size and shape with the interfascicular rays. Interfascicular rays taper abruptly centrifugally. Tracheids of the secondary xylem have scalariform thickenings and cross-fields possess oval–elongate scalariform pits. Secondary rays are parenchymatous and narrow, usually uni- to biseriate and less frequently organized in three to four seriates. The cortex is divided into an inner and outer zone, and primary xylem strands alternate at the nodal region. These stems conform to the features of the genus Arthropitys Geoppert and are most similar to Arthropitys lineata from the Early Permian of Europe; they also are similar to Arthropitys communis and Arthropitys hirmeri var. intermedia from Late Carboniferous coal balls in Europe and North America. However, the Chinese specimens are distinct in a number of ways including characters of the cells surrounding the carinal canals, the carinal canals themselves, features of the secondary xylem and also in their tracheid morphology, leading to the creation of a new species, Arthropitys junlianensis sp. nov. Implications of A. junlianensis on sphenopsid taxonomy, phylogeny and distribution are discussed, and the nearly identical morphology of this new sphenopsid to those of the Late Paleozoic coal swamps of Europe and North America is considered.

A new forewing venation pattern of the Tococladidae is proposed and the phylogenetic affinities of this family are discussed, based on Tococladus garrici nov. sp. This fossil comes from the Salagou Formation (Permian, Saxonian Group, Lodeve basin, France). The Tococladidae is assigned to the Archaeorthoptera BETHOUX and NEL, 2002 . The biostratigraphic implications of this discovery are briefly discussed, but it is still not possible to infer any definite conclusion about the age of this formation.

A new whole plant species of cordaitalean coniferophyte is reconstructed from a single Early Permian coal‐ball assemblage in northern China and is named Shanxioxylon sinense after its distinctive stem. This assemblage contains three cordaitalean whole plants reconstructed from evidence, including organs found in organic connection and other examples where two or more organs share distinctive anatomical features. With the exception of the fertile shoot systems, organs of the S. sinense plant may be ascribed to existing cordaitalean morphogenera, although in each case they represent distinct morphospecies. Stems have a septate central pith and have previously been assigned to S. sinense. Primary vascular architecture is sympodial, and primary xylem maturation of the cauline bundles is endarch. Adventitious roots are infrequently observed on smaller stems. Leaf traces are mesarch, diverging from the pith margin as a single bundle and approaching 8/21 phyllotaxis. Leaves are small and needle‐like. Roots are p...

A new genus of actinostelic ferns from the Permian of the Maranhao Basin, State of Tocantins, NE Brazil, is presented. Based on the cauline and petiolar anatomy and organization Dernbachia brasiliensis gen. nov. et sp. nov. is established to accommodate the newly collected material, which is preserved as silicified permineralization. The new fern is characterized by an interesting combination of a large actinostelic type of stem with an advanced dorsiventral type of petioles. The growth habit of D. brasiliensis should be reconstructed as a small-sized tree fern. The trunks are 60–170 mm in diameter and possess a big actinostele surrounded by a relatively narrow parenchymatous stem cortex extending into petiole bases and traversed by adventitious aerial roots. Leaf trace rapidly develops from an oval xylem trace over a Π-shaped strand to a pair of nearly circular-shaped strands. Comparative investigations of different Palaeozoic actinostelic ferns suggest relatively close relationships of the new fern with Asterochlaena from the Permian petrified forest of Chemnitz. Dernbachia may represent a highly specialized derivative from some ankyropterid ferns.

The stem anatomy and organization of new anatomically preserved Grammatopteris fern specimens are described from the Permian of the Maranhao Basin (NE Brazil). Grammatopteris freitasii nov. sp. is established to accommodate the newly collected material, which is preserved as silicified permineralization. On the basis of their anatomical details, Grammatopteris rigollotii , the type species originally described from the Permian of Autun, France, and Grammatopteris baldaufii , another species originally described from the Permian of Chemnitz, Germany, are re-examined and discussed. The generic diagnosis of Grammatopteris is emended. Furthermore, all species of the genus Grammatopteris are compared with Rastropteris pingquanensis (Galtier, Wang, Li and Hilton), a recently introduced type of fern from the Lower Permian of China. The Grammatopteris ferns are interpreted as showing a growth habit of small to medium-sized erect trees. Their trunks are 4–35 cm in diameter and possess an exarch maturated solid protostele surrounded by a dense mantle of petiole bases and more downwards completely clothed in a root mantle. Stem cortex contains different types of sclerotic tissue. Leaf trace vascular tissue developes from oval-shaped to tangentially elongated, typically bar-shaped strand. Grammatopteris ferns are thought to be of considerable importance or a link in the origin and early development of Osmundaceae.

Morphological variability of the vegetative fronds of Dicksonites pluckenetii (SCHLOTHEIM ex STERNBERG) STERZEL is described from new material collected in the Stephanian Basin of Graissessac (Southern Massif Central France). Complete bipartite fronds sometimes still attached to their parent stem allow us to reconstruct the plant as a scrambler/climber. This interpretation is supported by the relatively small slender stems with long internodes and densely covered by short spines, which are also present along the entire length of petioles. A fertile pinna with slightly reduced pinnules bearing up to six radially symmetrical synangia is interpreted as a portion of male frond of the same species; its organization confirms the relationships of Dicksonites with the Callistophytales as was already suggested by features of the female fronds.

Fossil remains of a fern were collected from the basalmost Carboniferous Tournaisian, Hardwick Formation of Queensland, Australia. The fern is described as an erect false trunk composed of intertwined branch systems and phyllophores embedded in a mesh of adventitious roots. The base of the trunk attained up to 50 cm in diameter and was composed almost totally of roots. Branching of the stems is isotomous. Each subsequent branch gives rise to a phyllophore and a geotropic adventitious root. Smaller roots arise from the bases of the phyllophores, as well as the larger roots, and all are covered with hairs and are directed horizontally. The two forms of roots are functionally complementary, the larger for support and absorption of water from the soil, the smaller for absorption in the humidity within the trunk. The repetitive branching of the stems concomitant with the increase of phyllophores and the two forms of adventitious roots comprised the oldest tree fern with false trunk known to this time. The phyllophores have no apparent phyllotaxy and many are abortive before reaching the exterior of the trunk. The cauline xylem strand, in transverse section, is a solid centrarch protostele while the phyllophore traces are simple and clepsydroid in outline. Xylem strands in the roots have four, rarely three or five, exarch protoxylem points. The combination of the very primitive anatomy with the arborescent habit is unique and the name Symplocopteris wyattii n. gen. et n. sp. is proposed. This plant is the oldest known zygopterid fern showing the clear anatomical and morphological distinction between stems, leaves and roots.

New material attributed to the species Iasvia reticulata ZALESSKY, 1934 and to a new species in this genus is described from the Salagou Formation (Saxonian Group, Lodeve basin). Preamble to the taxonomic section, the wing venation pattern of Orthoptera is discussed. The numerous described specimens yield decisive information about variability of wing venation within the genus, previously based on a single specimen from the Russian Permian. I. reticulata is the first species from the Lodeve basin that is already known from another site. The biostratigraphic implications are discussed.

Raphogla rubra gen. n., sp. n., oldest representative of the (Tettigoniidea & Gryllidea) is described from the Upper Permian of the Lodeve basin (France). Its phylogenetic relationships within the Ensifera are discussed. The new taxon occupies a very basal position, probably as sister group of the whole group (Tettigoniidea & Gryllidea).

International audience; Well-preserved specimens of Stauropteris oldhamia are described. The material was collected in the early 1920s from the Lower Westphalian (Early Pennsylvanian) Saurue seam from Belgium. The fossil plants occur as permineralized axes fragments within a coal ball. This study confirms most of the interpretations made by previous researchers. The observation of immature axis however suggests a less regular organization than previously interpreted beyond the three first branching orders. We also highlight the presence of profusely and dichotomously branched aphlebiae, the lack of laminate organs as well as the presence of hypodermal aerenchyma in all plant parts. We interpret these features as part of a very specialized assimilatory apparatus indicating an adaptation to a humid swamp environment.

Recent investigation on the Cathaysian flora of the Lower Permian Taiyuan Formation in Hebei Province, North China has led to the discovery of a new type of fern, Rastropteris pingquanensis gen. et sp. nov. Preserved as a permineralization, the stem, with a mantle of petiole bases and roots, shows a unique combination of anatomical characters. The vascular strand consists of a solid protostele with uniformly elongated tracheids and mesarch maturation of the xylem. In transverse section, the configuration of leaf trace xylem changes from reniform endarch to a tangentially elongated strand adaxially recurved at each end with several adaxial ridges. Stem and petiole cortex contains abundant sclerotic tissue with an interstitial tissue developed within the mantle of petiole bases and roots. A reinvestigation of Grammatopteris rigollotii, from the Permian of France, the type species of the genus allows interpretation of the latter as closer toRastropteris than any other fern. Both taxa are provisionally reported to an incertae sedis group of filicalean ferns possibly involved in the origin of Osmundaceae.

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.

Variation in branching pattern and leaf morphology in Sphenophyllum oblongifolium are investigated based on new compression material from the Upper Carboniferous (Stephanian) of France. Morphometric analysis reveals correlation between several parameters (internodal length, maximum diameter of axis, leaf length). Ontogenetic variability of axis diameter and internodal length is also demonstrated. There is no evidence of a rhythmic elongation of stems, which are interpreted as axes with a determinate but continuous growth. The vegetative system of S. oblongifolium is composed of four to five successive orders of axes. Branching is intermittent and diffuse, with an aleatory distribution of proleptic branches in which internode length may equal that in the parent stem. In the slender axes of the vegetative system of S. oblongifolium there is no clear hierarchy among successive orders of axes. This contrasts with the situation in the calamitean sphenopsids, where the successive orders of axes show distinct differences in diameter. Heterophylly of S. oblongifolium is documented in detail. As in some other species (e.g., Sphenophyllum emarginatum), heterophylly is interpreted partly as an adaptation to a more or less scrambling habit.

New palaeontological material was collected during recent extensive fieldwork in the Early Permian Perdasdefogu and Escalaplano basins (SE Sardinia). For the first time, an accurate biostratigraphic position can be assumed for the sediments of these two basins, on the basis of their fossiliferous content (floras; ostracods). Regional and inter-regional correlations are proposed and palaeogeographical implications are analysed.

A reinvestigation of the Triassic conifer pollen cone of Darneya shows evidence that clusters of pollen sacs are attached (adnate), at regular intervals, to the upper side of the stalk and that the distribution of stomata is restricted to the apical part of the abaxial side of the peltate scale. These features and others, such as the commissure visible on the stalk and the scale, suggest a dual nature of the male scale complex of Darneya which therefore is interpreted as an abaxial bract fused with an adaxial fertile shoot bearing several clusters of pollen sacs. This conifer pollen cone is thus considered as a compound strobilus (inflorescence) homologous with the female cone of the conifers and therefore with the cones, both male and female, of the cordaites.

Permineralized trunks of five different gymnospermous taxa have been collected in the Lower Carboniferous (Visean) of the southern Vosges. Some specimens are comparable to species previously discovered in this area and may be attributed to the genera Pitus and Eristophyton known from localities in Scotland and Silesia. The fifth type corresponds to the progymnosperm Protopitys which is recorded for the first time in the Vosges. Present evidence suggests an important taxonomic diversification of the arborescent gymnospermous element of the Visean vegetation which was similar in contemporaneous volcanic environments in the Vosges and Scotland.

Permineralised material ofRhacopteris lindseaeformis(Bunbury) Kidston andSpathulopteris obovata(Lindley & Hutton) Kidston, showing both external morphology and excellent anatomical preservation, is described from the Lower Carboniferous (?Asbian, Upper Viséan) tuffs and dolomitic ashes outcropping at Weaklaw–Gullane, East Lothian, Scotland. These specimens provide the first anatomical information on these two well-known plant compression genera. The rachises haveLyginorachis-type anatomy with distinctive characters in the two species.Spathulopterisrachises correspond toLyginorachis kingswoodenseMeyer-Berthaud, previously described from the localities of Kingswood and East Kirkton, whereasRhacopterisshows similarities with the petiole attributed toBiligneafrom Oxroad Bay. Both foliage types conform to seed-fern frond organisation. This new evidence contradicts previous interpretations ofRhacopterisas a fern or a progymnosperm. We suggest thatRhacopteris lindseaeformisandSpathulopteris obovatarepresent the foliage of some of the arborescent gymnosperms which are found associated in several contemporaneous localities.

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

Sporangia and spores from Loch Humphrey Burn, Kilpatrick Hills, Scotland, of late Tournaisian (Lower Carboniferous) age have been investigated by light microscopy, SEM and TEM. Spores tentatively assigned to Calamospora, obtained from sporongia referable to Protocalamostachys, are shown to possess a perispore of an unusual type and to differ considerably from those obtained from sporangia with helical wall cells which may also have been of sphenophyte origin. Spores from these latter sporangia are assigned to Punctatisporites cf. minutus. Spores of ferns from this locality are similarly investigated. These include Apiculatisporites from sporangia assignable to Corynepteris, Dictyotriletes micromuronatus sp. nov., and Knoxisporites cinctus (both from illustrated sporangia). These all demonstrate what are taken to be the remains of a perine. Structures associated with the aperture are in all cases simple, permitting only cautious assignment of these latter spores to a major fern taxon. Two lycopsid megaspores are described from this locality and provide the first evidence of this group in this flora. Their morphology and exine ultrastructure is compared to that of megaspores of similar type and age.

ACL-11-71; International audience; Little is known to date regarding the organisms that colonized the leaves of Carboniferous plants. This is due to a number of factors, including how the leaves were preserved, prepared for examination, and analyzed. Nevertheless, it is becoming increasingly clear that Carboniferous leaves were habitats for a wide variety of fungi. This paper describes fungal remains in cordaite leaves from the Upper Pennsylvanian Grand-Croix cherts in France. Within the intercellular system of the mesophyll occur intercalary and terminal swellings produced from an elaborate system of tenuous hyphae/filaments, as well as isolated putative (zoo-)sporangia and clusters of small unicells. Other fungal remains occur in bundle sheath cells. Although the systematic affinities of the fungi currently remain unknown, documenting their existence contributes to our understanding of the multiple levels of biological association and interaction that shaped the Carboniferous terrestrial ecosystems

ACL-11-15; International audience; A rachis of the fossil filicalean fern Botryopteris antiqua containing abundant septate hyphae with clamp connections is preserved in a late Visean (Mississippian; ~330 Ma) chert from Esnost (Autun Basin) in central France. Largely unbranched tubular hyphae pass from cell to cell, but may sometimes produce a branch from a clamp connection. Other clamp-bearing hyphae occur clustered in individual cells or small groups of adjacent host cells. These hyphae may be tubular, catenulate with numerous hyphal swellings, or they may display a combination of both. The Visean hyphae with clamp connections predate Palaeancistrus martinii, the heretofore oldest direct fossil evidence of Basidiomycota, by some 25 Ma

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

It is usually considered that after the extinction of the Devonian tree Archaeopteri s, no new arborescent lignophytes were established before the late Tournaisian. A reassessment of this pattern is presented here based on a three-fold approach: a re-evaluation of the taxic diversity of Tournaisian lignophyte trees based on descriptions of new plants from palaeotropical latitudes, a study of the patterns of phenotypic changes occurring among early lignophytes using a principal coordinate analysis and a phylogenetic analysis of the affinities of the arborescent taxa. The best supported results indicate that a substantial taxonomic and phenotypic diversity of arborescent lignophytes was already established in the first part of the Tournaisian, including some taxa that persisted until the Serpukhovian. Two genera may have originated in the Late Devonian and crossed the Devonian–Carboniferous boundary. Fewer originations and a decrease in phenotypic diversity occurred in the Visean. The phenotypic distinctiveness of tree stems compared with those of other growth forms in the lignophytes is assessed. We propose a scenario in which the presence of lignophyte trees is continuous across the Devonian–Carboniferous boundary, with arborescent taxa distinct from Archaeopteris already present in the latest Devonian, possibly in upland floras, and diversifying significantly soon after the Devonian–Carboniferous boundary. Supplementary material: A list of taxa, characters and matrices used in the principal coordinate analysis and phylogenetic analysis is available at http://www.geolsoc.org.uk/SUP18447.