In recent years, there has been a dramatic increase in studies on plant-arthropod interactions in the fossil record. However, relatively few studies have targeted pre-Permian floras, which has hindered the reconstruction of trophic relationships in Carboniferous coal-forming ecosystems. Here, we document new evidence of arthropod and pathogen damage on Medullosales, which were prominent gymnosperm elements of Carboniferous coal forests, from the Nord-Pas-de-Calais Coalfield. We record 28 damage types (DTs) among 1206 fossil plant specimens belonging to Alethopteris and Lonchopteris. The damage categories are ascribed to seven functional feeding groups (FFGs): hole feeding (nine DTs), margin feeding (five DTs), surface feeding (three DTs), piercing and sucking (three DTs), oviposition (six DTs), galling (one DT), and pathogen attack (one DT). Rarefaction analyses evaluated sample completeness and clarified the damage incidence patterns. Our study provides the first quantitative assessment of herbivory from an Early-Middle Pennsylvanian terrestrial ecosystem. Although the proportion of damaged foliage is low (5.64% of specimens), its diversity is higher than in many younger (Late Pennsylvanian) floras. This suggests expansion and diversification of herbivore and pathogen attack at that time, which is consistent with the increased dominance of arborescent seed plants and the ascendancy of winged insects in the terrestrial fauna of the region. The presence of multiple feeding strategies on the studied medullosalean foliage indicates that this group of plants provided key food resources for diverse arthropod groups occupying the Nord-Pas-de-Calais palaeoforests. Almost all known types of FFGs are documented in the NordPas-de-Calais fossil assemblages, suggesting that modern trophic relationships were likely established earlier than previously documented in Euramerican coal swamps.

The stomatal structure of the medullosalean frond species Odontopteris schlotheimii is documented for the first time. This supports the view that it is taxonomically distinct from the morphologically similar but rather older frond-species Odontopteris cantabrica. Evidence is also presented that supports the view that the types of Neuropteris pseudoblissii are conspecific with O. schlotheimii.

Geoheritage is the key source of evidence on which the geosciences are founded and geoconservation aims to protect that heritage. There are two main classes of geoheritage: in-situ geoheritage represented mainly by geosites and ex-situ geoheritage represented by collections of specimens such as in museums. Although they may seem conceptually different, in-situ and ex-situ geoheritage serve essentially the same function, to provide the empirical foundations of the geosciences. Geoconservation of both types of geoheritage is therefore vital for the continued successful development of the geosciences, allowing research models to be tested and verified, providing resources for formal education, and improving the public understanding of the subject.

Research. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/ 4.0/).

A new compilation of late Palaeozoic plant families has been analysed using diversity rate metrics including for the first time a randomized time-continuous approach, and multivariate techniques including network analysis. The results reveal the major vegetation changes in Mississippian to Guadalupian times, including the Palaeophytic-Mesophytic flora transition. Palaeophytic vegetation was globally dominated by lycopsids and filicopsids, but these groups underwent high extinction rates and a globally reduced diversity towards the end of the Carboniferous. Seed plants also saw high extinction rates at this time, but global diversities were maintained by increased origination rates with the expansion of the replacing Mesophytic vegetation. Network analysis has shown how complexity of floral dynamics increased through the Carboniferous, before a dramatic decline around the Carboniferous-Permian boundary. No relationship is seen between the balance of global origination-extinction rates and major ecological changes, such as the growth and decline of the Late Palaeozoic Ice Age, or the collapse of the palaeotropical coal swamp biome that was largely responsible for the diversity of Palaeophytic vegetation. Further work is needed on the effect of palaeogeography on this Palaeophytic-Mesophytic vegetation transition.

Lyginopteridalean fossil fronds found abundantly in deposits of the Pennsylvanian‐age (late Carboniferous) coal swamps have historically been identified as Eusphenopteris neuropteroides . However, these fossils have been referred by Van Amerom to three distinct fossil‐species: E. schumannii , E. neuropteroides and E. leonardii . The types of these three species epithets are reviewed and fully documented, as well as the emended diagnoses of the fossil‐species. The three species appear to represent a progressive change in frond morphology through Westphalian times, possibly reflecting changes in palaeoclimate and landscape.

Foliage remains from Saberian-age (late Carboniferous-Pennsylvanian) strata of the Central and Western Bohemian basin complex are interpreted as a new species of the putative medullosalean pteridosperm fossil-genus Blazyopteris and is named B. feistmantelii. It is only the second known species of Blanzyopteris frond, the other being B. praedentata. Both species appear to be foliage of lianescent plants.

A group of equisetalean shoots with distinctive small leaves occurs widely in the upper Bashkirian and lower Moscovian coal-bearing deposits of Euramerica. They have often been named Asterophyllites grandis and Asterophyllites charaeformis in the past, but the use of these names is illegitimate for these species. In this study, these shoots have been assigned to five fossil species: Asterophyllites delicatulus, Asterophyllites parvulus, Asterophyllites gracilis, Asterophyllites taylorianum, and Asterophyllites lubnensis. Two of the species are associated with Calamostachys strobili, while the other three are associated with Palaeostachya strobili. The distribution of the shoot species partly reflects differences in elevation and substrate conditions of where the parent plants grew.

Fossil plants are key to many palaeobiogeographic and deep time diversity studies, but correctly interpreting them can be fraught with problems due to fragmentation in the fossil record. A typical vascular plant comprises 10-12 separate organs depending on its systematic affinity, but complete individuals are exceptionally rare. Fragmentation can result from multiple processes including ontogeny during the plant's life-cycle, or from postmortem taphonomic processes in fluvial systems. In traditional approaches where raw data is amassed directly in the field, from existing physical collections or electronic databases, duplication is inevitable in that different organs of the same plant species may be inadvertently counted independently, skewing results. Here we outline normalization methods for filtering the palaeobotanical data to remove taxonomic duplications, with examples provided from different types of preservation. We use two case studies to highlight the impact of normalization by analysing raw (unfiltered) versus normalized (filtered) data. The first case study evaluates plant data from the late Permian and Triassic compression/impression floras of South China, focussing on species richness/diversity assessments through the Permian-Triassic mass extinction and its recovery. In this case study, normalization reduced the number of taxa but revealed more detailed evolutionary patterns including the magnitude of floristic turnover, previously obscured by the fragmental preservation typical of plant fossils and nomenclature. The second case study evaluates Carboniferous to Permian anatomically preserved coal-ball floras from Europe, North America and China, focussing on palaeobiogeography and floral provinciality. Normalization reduced the number of coal-ball assemblages when surveyed at both genus and species level but revealed differences in relationships and floristic endemism. We conclude that normalized results should be considered alongside raw data, as they show important and complementary information which can greatly aid in overall interpretation.

Much of what we know about terrestrial life during the Carboniferous Period comes from Middle Pennsylvanian (similar to 315-307 Mya) Coal Measures deposited in low-lying wetland environments(1-5). We know relatively little about terrestrial ecosystems from the Early Pennsylvanian, which was a critical interval for the diversification of insects, arachnids, tetrapods, and seed plants(6-10). Here we report a diverse Early Pennsylvanian trace and body fossil Lagerstatte (similar to 320-318 Mya) from the Wamsutta Formation of eastern North America, distinct from coal-bearing deposits, preserved in clastic substrates within basin margin conglomerates. The exceptionally preserved trace fossils and body fossils document a range of vertebrates, invertebrates and plant taxa (n = 131), with 83 distinct foliage morphotypes. Plant-insect interactions include what may be the earliest evidence of insect oviposition. This site expands our knowledge of early terrestrial ecosystems and organismal interactions and provides ground truth for future phylogenetic reconstructions of key plant, arthropod, and vertebrate groups.

The Nord-Pas-de-Calais Coalfield is formed by an almost continuous succession of upper Carboniferous deposits, from which an extremely diverse macroflora has historically been described. Recent evidence has highlighted a clear pattern of changing species diversity, showing some differences from what is seen in other coalfields of Variscan Euramerica. We further study this significant macroflora, focusing on the biostratigraphical changes and their palaeoecological implications. Clustering and ordination analyses have indicated key floral discontinuities that enable the standard regional macrofloral biozones to be recognized in the Nord-Pas-de-Calais Coalfield. By combining these results with the previous diversity studies, six distinct phases in the evolution of the coal swamp vegetation in north-eastern France can be identified: (1) an initial invasion of peat substrate vegetation in the earliest Langsettian; (2) a rapid diversification of the clastic substrate vegetation in the early-middle Langsettian; (3) a more gradual diversification of the vegetation of both clastic and peat substrates during the late Langsettian to middle Duckmantian glacial phase C3; (4) the appearance of more characteristically late Westphalian, but less diverse floras during the late Duckmantian to early Bolsovian C3-C4 interglacial phase; (5) a marked increase in species diversity in the middle-late Bolsovian, coinciding with the onset of the C4 glacial phase; and (6) a marked reduction in species diversity, and the appearance of new medullosaleans and marattialeans in the Asturian, possibly linked to climate change. The evidence clearly shows how this palaeotropical swamp vegetation was responding to climate change and orogenic landscape changes during Westphalian times.

The coal-bearing lower Clackmannan Group of Scotland has yielded diverse fossil floras of Serpukhovian (late Mississippian) age dominated by arborescent lycopsids, equisetopsids, ferns and lyginopteridalean pteridosperms. Similar macrofloras of the same age have been reported from coal-bearing deposits of Maine-et-Loire (NW France) and Upper Silesia (Czech Republic and Poland). These fossil floras together reflect the earliest development of the coal swamp biome in tropical Euramerica. The biome appeared on newly-exposed areas of coastal plain that formed as result of lowered sea-levels during the first major cooling phase of the Late Palaeozoic Ice Age. A new combination Artisophyton chalmersii is proposed based on Megaphyton chalmersii Goodlet.

During recent years, different studies have focused on characterising plant diversities in the Carboniferous environments of the Variscan Foreland. One of these areas, the Nord-Pas-de-Calais Coalfield, has a Namurian–Westphalian sequence that has historically yielded abundant evidence of vegetation change, but to date, little attention has been paid to its macrofloral diversity dynamics. Here we show, for the first time, a comprehensive characterisation of the diversity changes and macroevolutionary patterns from this coalfield. The results show evidence of low levels of species richness during the Namurian, followed by an exponential diversification at the base of Westphalian. Duckmantian–Bolsovian species diversity continues to progressively increase, suggesting relatively stable conditions at that time. Maximum species richness is observed at the mid-Bolsovian followed by a major depletion during the Asturian. Overall, this pattern is quite similar to that seen in other parts of the Variscan Foreland. However, we see Nord-Pas-de-Calais vegetation diversified earlier than those in the British parts, probably because the dynamics of marine incursions and lacustrine conditions delayed its development in the latter areas. Furthermore, we also see the Asturian decline of the Nord-Pas-de-Calais coal swamp occurred later than in other basins, such as in the Pennines, Ruhr, and South Wales. This scenario suggests that the collapse of this biome was probably caused by increased sediment influx and reduced subsidence, resulting from the northwards migration of the Variscan Mountains. This further supports other studies in Europe advocating that climate change was at most only a subsidiary factor in the collapse of the Pennsylvanian coal swamp biomes.

Abstract For the west European regional chronostratigraphic framework, the Cantabrian substage was conceived as covering a widely apparent stratigraphic gap between the top of the Westphalian and the base of Stephanian A, the lowest unit of the Stephanian. A continuous depositional history covers this time gap in the Cantabrian region of Spain; the upper limit of this interval was defined by the succeeding Barruelian substage, equivalent to Stephanian A. Intense tectonic and magmatic activity characterizes this period; the Iberian orogenic belt was an essentially linear feature buckled through the Late Pennsylvanian into the tightly folded Cantabrian Orocline. This evidences an extensive southern foreland to the Variscides, in which the coal-swamp biome persisted through the Late Pennsylvanian, supporting biostratigraphical correlation with the Donbass. New high precision U–Pb CA-ID-TIMS radiometric dating of tonstein horizons supports a preliminary time-framework of regional substages: base of the Asturian (proposed, ex-Westphalian D) c. 310.7 Ma; base of the Cantabrian c. 307.5 Ma; base of the Barruelian (ex-Stephanian A) c. 304.9 Ma; base of the Saberian (proposed) c. 303.5 Ma. The Cantabrian and Barruelian embrace the entire Kasimovian of the global time-scale, and the top of the Barruelian is essentially coincident with the base of the Gzhelian.

Seven fossil–species can be distinguished within the range of late Carboniferous and early Permian equisetopsid (“horsetail”) foliage formerly assigned to Annularia stellata. The shoots bearing this foliage also produced distinctive strobili often known as Calamostachys tuberculata. These foliage species can be differentiated by leaf and whorl morphology, and each species has a distinct geographical and stratigraphical range. The group first appeared in the intramontane basins of the Variscan Mountains in the late Duckmantian, and then expanded into the lowland paralic coal swamps in the Bolsovian–Asturian. The group continued to flourish in coal swamp refugia during the Stephanian but eventually disappeared during the early Permian.

The Silurian–Devonian plant radiation was a critical development in the evolution of early terrestrial ecosystems. Characterizing the diversity dynamics of this radiation has been a focus of numerous studies. However, little is known about the impact of geological bias on our perception of this biodiversification. Here, we use a new, comprehensive compilation of plant occurrences from North America, together with a Macrostrat lithological dataset, to elucidate the relationships between the palaeobotanical and geological records of early land plants. Results show that observed raw diversity patterns at both species and genus rank are significantly correlated with fluctuations of sedimentary rock volume, especially of non‐marine fossiliferous deposits. The lack of terrestrial sedimentary deposits before the Emsian (Early Devonian) makes it difficult to obtain an accurate depiction of the pre‐Emsian plant diversification in North America. However, complementary analyses reveal that sampling‐standardized diversity patterns partially correct the raw trajectories, especially at the genus‐level if enough preserved non‐marine sediments are available for sampling. Our findings highlight that geological incompleteness remains a fundamental bias for describing early plant diversification. This indicates that, even when sampling is extensive, observed diversity patterns potentially reflect the heterogeneity of the rock record, which blurs our understanding of the early history of land vegetation.

A new species of adpression cordaitalean cone is described from the Stephanian C (Upper Pennsylvanian) Vale da Mó “Formation” of the Buçaco Carboniferous Basin, central western Portugal. The macro- and micro-morphology of the new species, named Florinanthus bussacensis sp. nov., is described and its ontogenetic and palaeoecological significance assessed. The new cone species is erected on the basis of three primary axes with secondary fertile shoots with fimbriate apices. The number, linear-filiform shape and small size of the structures preserved on the distal parts of the scales suggests they represent pollen sacs, thus the new species F. bussacensis is considered to represent a male fructification. The new species is characterized by pollen sacs grouped in 4 to 5 clusters, composed of 4–7 basally fused sacs, and ovate to lanceolate-shaped sterile scales. The new cone seems to present different maturation states (mature to overmature) of its shoots, and its association with Cordaites leaves and Carpolites and Cardiocarpus seeds/ovules, suggests the new species was probably produced by the same parent plant species. The morphological and taxonomic diversity of the Pennsylvanian Cordaitaceae fructifications in western Variscan Euramerica remains largely unclear, due to the difficult recognition of these structures in the fossil record. This is the second record of a cordaitalean cone in the Carboniferous of Portugal, despite the abundance of cordaitalean remains (mainly of leaves, seeds, stems and roots) in its sequences. The difficult recognition of these structures in poor preservation conditions can easily make them go unnoticed and is more likely to be this the cause of their poor knowledge than a hypothetical limited record.

The Silurian–Devonian plant radiation was an event triggered by the progressive colonization of subaerial habitats. Nevertheless, it is still unclear whether this radiation was globally uniform or whether alternative diversification scenarios emerged depending on the geographical context. Here, we report on early land plant diversity patterns across different previously defined palaeogeographical units (i.e., Laurussia, Siberia, Kazakhstania, NE, NW and South Gondwana). Results reveal apparent diachronous events of diversification and extinction partly resulting from uneven sampling effort, especially in Gondwana. Global diversity patterns are most similar to the Laurussian curve suggesting that the observed global dynamics are mostly controlled by the historically best-sampled continents. Nevertheless, changes in floral composition through time become less prone to sampling biases, and reveal geographical disparities that indicate a non-random distribution of the Silurian–Devonian vegetation. Consequently, we further performed a set of multivariate analyses to revisit the palaeophytogeographical signal through four time-intervals (i.e., Silurian–Lochkovian, Pragian–Emsian, Middle and Late Devonian), which revealed that spatial differentiation of vegetation was mainly controlled by climatic conditions and to a lesser extent geographical barriers. Most importantly, we find the maximum provincialism during cooler periods such as during the Silurian–Lochkovian and Middle Devonian, whilst warmer periods (Pragian–Emsian and Late Devonian) coincided with increased cosmopolitanism among early land plants.

The "Coteaux du Pont Barre" in Beaulieu-sur-Layon is a Regional Natural Reserve which is home to exceptional flora and fauna. Recently fossil plants have been discovered at the site adding to its natural heritage significance. The exposure which is part of the "Sillon Houiller de la Basse-Loire" contains Serpukhovian-age (330-320 Ma) remains of sphenophytes, ferns, and lyginopteridopsid and cycadopsid pteridosperms, which are described for the first time as well as the geology of the site. Most Carboniferous macroflora previously described from the Maine-et-Loire has been based on ex situ specimens from now abandoned and inaccessible coal mines. The newly described macroflora shows evidence of in situ remains and differs somewhat in composition from those reported from the coal workings, especially in the total absence of lycopsids and Calymmotheca pteridosperms, and instead having abundant medullosalean foliage (Neuralethopteris). The co-occurrence of Sphenopteris elegans and Neuralethopteris densifolia suggests a slightly younger age compared to the macrofloras documented from the coal-bearing deposits. However, this could be an ecological consequence of the flora growing in better-drained substrate habitats.