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The Chateaupanne Unit belongs to the South Armorican domain of the Armorican Massif (France), which is part of the Variscan belt. This unit includes two Lower Devonian plant levels and one of them corresponds to the Basal Member of the Chalonnes Formation. A sedimentological and palaeontological analysis of these fossiliferous deposits from the Chateaupanne quarry (Montjean/Loire, Maine et Loire, France) is presented here for the first time. The age determination based on palynology indicates that the locality records the earliest occurrence of plant megafossils in the Armorican Massif. Their presence suggests an emergence event that has never been described before. Our study highlights the promising potential of the Basal Member of the Chalonnes Formation to aid in understanding these occurrences, and provides new insights into the history of the Variscan belt. Keywords: early land plants, Lower Devonian, spores, acritarchs, emergence event, unconformity, storm. doi: 10.1017/S001675681000004X

Abundant and well-preserved material of the ligulate lycopsid genus Leclercqia is reported from a new Middle Devonian locality in northeastern Queensland (Australia). The plants occur in a chert horizon in the Storm Hill Sandstone of the Dosey-Craigie Platform. Lithological data and conodont analyses combined with information from in situ spores provide an age for the plant levels ranging from Eifelian, possibly Middle Eifelian, to Early Givetian. Plant taxonomic identification is based on vegetative and fertile stems that display both external morphology and anatomy. This material represents the best documented occurrence of Leclercqia outside Laurussia and possibly the earliest in Gondwana; it provides evidence that colonization of Gondwana by the species L. complexa was contemporaneous to that of Siberia and Kazakhstan. Analysis of the distribution patterns of L. complexa suggests that it was adapted to a wide range of environments, but within certain limits which we hypothesize to be those of a climatic belt. Such considerations support previous studies using other biological data, such as faunas and palynomorphs, for reconstructing Devonian palaeogeography. They favour a close proximity of Laurussia and Gondwana rather than the occurrence of a wide ocean separating the two palaeocontinents in Middle Devonian times. Keywords: Australia, Devonian, Gondwana, Lycopsida, palaeogeography.

The advent of reproduction by seeds was one of the most essential evolutionary steps in plant history: the vast majority of living plants are seed plants (spermatophytes). The seed habit includes the following set of defining characteristics: (1) heterospory, (2) occurrence of a single megaspore that germinates within an indehiscent megasporangium (nucellus) retained on the sporophyte, (3) enclosure of the megasporangium in an integument, and (4) capture of pollen before seed dispersal. Contrasting hypotheses about the single / multiple, saltational / gradual origin of the seed habit, and identification of the closest relatives of seed plants (aneurophytalean or archaeopteridalean progymnosperms) are still matters of considerable debate. Early seeds did not possess the whole set of characters that define modern seeds. They lacked a true micropyle and an entire integument, and none has yet been discovered containing an embryo. Hence they are called preovules.

Land plants comprise the bryophytes and the polysporangiophytes. All extant polysporangiophytes are vascular plants (tracheophytes), but to date, some basalmost polysporangiophytes (also called protracheophytes) are considered non‐vascular. Protracheophytes include the Horneophytopsida and Aglaophyton/Teruelia. They are most generally considered phylogenetically intermediate between bryophytes and vascular plants and are therefore essential to elucidate the origins of current vascular floras. Here, we propose an alternative evolutionary framework for the earliest tracheophytes. The supporting evidence comes from the study of the Rhynie chert historical slides from the Natural History Museum of Lille (France). From this, we emphasize that Horneophyton has a particular type of tracheid characterized by narrow, irregular, annular and/or, possibly spiral wall thickenings of putative secondary origin, and hence that it cannot be considered non‐vascular anymore. Accordingly, our phylogenetic analysis resolves Horneophyton and allies (i.e. Horneophytopsida) within tracheophytes, but as sister to eutracheophytes (i.e. extant vascular plants). Together, horneophytes and eutracheophytes form a new clade called herein supereutracheophytes. The thin, irregular, annular to helical thickenings of Horneophyton clearly point to a sequential acquisition of the characters of water‐conducting cells. Because of their simple conducting cells and morphology, the horneophytophytes may be seen as the precursors of all extant vascular plant biodiversity. [ABSTRACT FROM AUTHOR]

The marine fossil record shows five mass extinctions at the Ordovician–Silurian, Frasnian–Famennian (Late Devonian), Permian–Triassic, Triassic–Jurassic and Cretaceous–Palaeogene transitions. However, only one of these significantly disrupted plant evolution. We clearly need to look again at what we really mean by mass extinctions events, especially in the context of the so‐called sixth mass extinction occurring today. [ABSTRACT FROM AUTHOR]

Lycopsids are a minor component of current terrestrial herbaceous floras. However, lycopsid fossil diversity shows a great diversity and disparity including heterosporous woody plants, e.g. the giant isoetaleans that populated the extensive Pennsylvanian wetlands. The earliest known isoetaleans come from late Devonian localities from China. Here, we describe Lilingostrobus chaloneri gen. et sp. nov., a new isoetalean lycopsid from the Upper Devonian (Famennian) Xikuangshan Formation of China (Hunan Province, South China), which adds to the already impressive diversity of the Devonian lycopsids from China. Lilingostrobus shows an unusual combination of characters. This new plant is pseudoherbaceous, with a possible tufted habit, and consists of narrow axes with rare isotomies. The stem includes small quantities of secondary xylem. Each fertile axis bears one terminal strobilus comprising sporophylls ending in a very long upturned lamina. Microspores and putative megaspores have been found, but whether the plant has mono- or bisporangiate strobili is unknown. Importantly, our cladistic analysis identifies Lilingostrobus as a direct precursor of Isoetales, which provides new insights into the early evolution of lycopsids. [ABSTRACT FROM AUTHOR]

The article offers information on the putative late ordovician land plants. Topics discussed include Ordovician succession cropping out in a village in Poland Zbrza, Kielce County; history of vegetation; and the information on the graptolite fauna along with hypothesis relating to the early evolution of land plants.

A new basal land plant, Teruelia diezii gen. et sp. nov., is described from the shallow-water marine deposits of the Lower Devonian (Lochkovian-Pragian) Nogueras Formation of the Iberian Peninsula (north Gondwana palaeocontinent). Teruelia is preserved as a compression fossil and consists of isotomously branched, robust stems terminated in large, fusiform, twisted sporangia. This morphology suggests that Teruelia is very probably equivalent to Aglaophyton, a permineralized early polysporangiophyte known up to now only from the Lower Devonian (early Pragian to ?earliest Emsian) Rhynie Chert in Scotland (Laurussia palaeocontinent), which represents an early terrestrial hot-spring ecosystem. Accepted phylogenies identify Aglaophyton as sister to vascular plants. Our phylogeny-based results identify the Aglaophyton/ Teruelia biological entity (i.e. Aglaophyton anatomical characters plus Teruelia external morphology) as the most direct vascular plant precursor. It shows that at least one Rhynie Chert type plant had a much wider distribution than previously known and suggests that Aglaophyton was not restricted to hydrothermal environments, unlike other Rhynie Chert plants. [ABSTRACT FROM AUTHOR]

A new well-preserved spore assemblage has been discovered from the Lower Devonian Nogueras Formation of Mezquita de Loscos (Teruel Province, north-eastern Spain). The palynoflora includes 34 spore species belonging to 20 genera, among which 14 are new for the locality, e.g.Apiculiretusispora,Brochotriletes,Cirratriradites,Iberoespora,KnoxisporitesandVerrucosisporites. The assemblage is mainly composed of trilete spores, while tripapillate and monolete forms are also observed. An early Pragian age is suggested for the fossil site. Specimens ofLatosporites ovalis, a species previously well-documented only from the late Pragian–Emsian of Saudi Arabia and Brazil, are found in this assemblage and represent to date the earliest known occurrence of this species. Besides the description of the palynoflora, we also provide here a synthesis of the plant-bearing localities of the study area. [ABSTRACT FROM PUBLISHER]

Mass extinctions are crucial to understanding changes in biodiversity through time. However, it is still disputed whether extinction dynamics in the marine and terrestrial biotas followed comparable trajectories. For instance, while marine realms have suffered five strong depletions in diversity, the so-called ‘Big Five’ mass extinctions, only the end-Permian event appears to have also resulted in a major abrupt reduction in continental diversity. However, recent evidence based on the diversity dynamics of vegetation has suggested the presence of two major episodes of extinction in the terrestrial environments, at the end-Carboniferous and the end-Permian times. This apparent contradiction is addressed in the present study. Here, we show that while the end-Carboniferous plant extinction was focused on particular environments (e.g. tropical wetlands) and affected mainly the free-sporing plant diversity (i.e. lycopsids, ferns and progymnosperms), only the end-Permian mass extinction had devastating effects on vegetation on a global scale. If we take the biosphere as a whole, the results highlight that the end-Permian biotic crisis was the only genuine global mass extinction event, affecting widely both the marine and terrestrial environments. [ABSTRACT FROM PUBLISHER]