scholarly journals Archaeosporites rhyniensis gen. et sp. nov. (Glomeromycota, Archaeosporaceae) from the Lower Devonian Rhynie chert: a fungal lineage morphologically unchanged for more than 400 million years

2020 ◽  
Vol 126 (5) ◽  
pp. 915-928 ◽  
Author(s):  
Carla J Harper ◽  
Christopher Walker ◽  
Andrew B Schwendemann ◽  
Hans Kerp ◽  
Michael Krings
Keyword(s):  
Lower Devonian ◽  
Arbuscular Mycorrhizas ◽  
Land Plant ◽  
Thin Sections ◽  
Early Devonian ◽  
Fungal Lineage ◽  
Transmitted Light Microscopy ◽  
Rhynie Chert ◽  
History Of ◽  
Early Land

Abstract Background and Aims Structurally preserved arbuscular mycorrhizas from the Lower Devonian Rhynie chert represent core fossil evidence of the evolutionary history of mycorrhizal systems. Moreover, Rhynie chert fossils of glomeromycotan propagules suggest that this lineage of arbuscular fungi was morphologically diverse by the Early Devonian; however, only a small fraction of this diversity has been formally described and critically evaluated. Methods Thin sections, previously prepared by grinding wafers of chert from the Rhynie beds, were studied by transmitted light microscopy. Fossils corresponding to the description of Archaeospora spp. occurred in 29 slides, and were measured, photographed and compared with modern-day species in that genus. Key Results Sessile propagules <85 µm in diameter, some still attached to a sporiferous saccule, were found in early land plant axes and the chert matrix; they developed, in a similar manner to extant Archaeospora, laterally or centrally within the saccule neck. Microscopic examination and comparison with extant fungi showed that, morphologically, the fossils share the characters used to circumscribe the genus Archaeospora (Glomeromycota; Archaeosporales; Archaeosporaceae). Conclusions The fossils can be assigned with confidence to the extant family Archaeosporaceae, but because molecular analysis is necessary to place organisms in these taxa to present-day genera and species, they are placed in a newly proposed fossil taxon, Archaeosporites rhyniensis.

Palaeonema phyticum gen. n., sp. n. (Nematoda: Palaeonematidae fam. n.), a Devonian nematode associated with early land plants

Nematology ◽  
2008 ◽  
Vol 10 (1) ◽  
pp. 9-14 ◽  
Author(s):  
George Poinar Jr ◽  
Hans Kerp ◽  
Hagen Hass
Keyword(s):  
Early Stage ◽  
Land Plant ◽  
Terrestrial Plants ◽  
Early Devonian ◽  
Plant Parasitism ◽  
New Family ◽  
The Earth ◽  
The Family ◽  
The Face ◽  
Early Land

AbstractNematodes are one of the most abundant groups of invertebrates on the face of the earth. Their extremely poor fossil record hinders our ability to assess just when members of this group invaded land and first became associated with plants. This study reports fossil nematodes from the stomatal chambers of the Early Devonian (396 mya) land plant, Aglaophyton major. These nematodes, which are tentatively assigned to the order Enoplia, are described as Palaeonema phyticum gen. n., sp. n. in the new family Palaeonematidae fam. n. Diagnostic characters of the family are: i) cuticular striations; ii) uniform, cylindrical pharynx with the terminal portion only slightly set off from the remainder; and iii) a two-portioned buccal cavity with the upper portion bearing protuberances. The presence of eggs, juveniles and adults in family clusters within the plant tissues provide the earliest evidence of an association between terrestrial plants and animals and may represent an early stage in the evolution of plant parasitism by nematodes.

The first zosterophyll from the Lower Devonian Rhynie Chert, Aberdeenshire

1991 ◽  
Vol 82 (4) ◽  
pp. 324-332 ◽  
Author(s):  
A. G. Lyon ◽  
Dianne Edwards
Keyword(s):  
Lower Devonian ◽  
New Genus ◽  
New Genus And Species ◽  
Early Devonian ◽  
Precise Positioning ◽  
Cortical Zone ◽  
Lack Of Information ◽  
Rhynie Chert

ABSTRACTFragmentary remains of a vascular sporophyte from the Rhynie Chert are described as a new genus and species, Trichopherophyton teuchansii. The plant, which is characterised by the possession of unicellular spinous hairs, exarch xylem and laterally attached, marginally dehiscent sporangia, is assigned to the Zosterophyllophytina, but lack of information on the arrangement of sporangia prevents its more precise positioning within the subdivision. Unusual features include the combination of circinate tips to axes with almost terete xylem strands, and the lack of a thick-walled outer cortical zone. Associated axes, lacking spinous hairs, but having papillate or rhizoid-like epidermal emergences, are interpreted as likely rhizomes of Trichopherophyton. Features, such as unicellular spinous hairs, rhizoid-like emergences, circinate tipsand parenchymatous cortex are considered in relation to the functioning and growth of aplant inhabiting an early Devonian wetland.

scholarly journals A Lower Devonian age for the Corvock Granite and its significance for the structural history of South Mayo and the Laurentian margin of western Ireland

2021 ◽  
Author(s):  
John Graham ◽  
Nancy Riggs
Keyword(s):  
Lower Devonian ◽  
Early Devonian ◽  
North East ◽  
The North ◽  
Granite Emplacement ◽  
History Of ◽  
Western Ireland ◽  
Laurentian Margin ◽  
Devonian Age ◽  
Restraining Bend

The Silurian Croagh Patrick succession, which crops out just south of a fundamental Caledonian structural zone near Clew Bay, western Ireland, is a series of psammites and pelites with a strong penetrative cleavage. These rocks are intruded by the Corvock granite. A suite of minor intrusions associated with the granite contains the regional cleavage whereas the Corvock granite is undeformed. New U-Pb dates are 413 + 7 / -4 Ma for a strongly cleaved sill and 410 ± 4 Ma for the main granite and closely constrain the age of crystallization of the granite and coeval cleavage formation as Lower Devonian (Lochkovian or Pragian), implying syn- to late-kinematic granite emplacement. These data are consistent with evidence for strong sinistral shear shown by the Ox Mountains granodiorite just to the north-east dated at 412.3 ± 0.8 Ma. This Devonian cleavage is superimposed on Ordovician rocks of the South Mayo Trough. The localisation of the strong deformation is interpreted as being due to its position at a restraining bend during regional sinistral motion on a segment of the Fair Head-Clew Bay Line to the north. Contemporaneous deformation in the syn-kinematic Donegal batholith suggests a transfer of sinistral motion to this intra-Grampian structure rather than simple along-strike linkage to the Highland Boundary Fault in Scotland. Our new data indicate diachronous deformation during the late Silurian and early Devonian history of the Irish and Scottish Caledonides and also support previous interpretations of diachronous deformation between these areas and the Appalachian orogens.

The Early Devonian (Pragian) zosterophyll Bathurstia denticulata Hueber

2000 ◽  
Vol 78 (2) ◽  
pp. 193-207 ◽  
Author(s):  
Michele E Kotyk ◽  
James F Basinger
Keyword(s):  
Phylogenetic Relationships ◽  
Lower Devonian ◽  
Canadian Arctic ◽  
Land Plants ◽  
Canadian Arctic Archipelago ◽  
Large Collection ◽  
Early Devonian ◽  
Northern Canada ◽  
Early Land

Approximately 86 specimens of Bathurstia denticulata Hueber were collected from upper Bathurst Island and lower Stuart Bay beds of Bathurst Island, Canadian Arctic Archipelago. Bathurstia was a component of a zosterophyll-dominated flora of Pragian age (Lower Devonian) that existed at low paleolatitudes in northern Canada. The large collection of well-preserved materials permits reconstruction of the plant as a robust scrambler of about 30 cm in height. Stems bear short, shelf-like emergences in two rows, and branch isotomously, although sparsely. Rooting organs, representing some of the oldest known for land plants, arise from the main aerial axes, although they are also associated with small, subordinate shoots interpreted as plantlets. Numerous specimens are fertile, with sporangia borne in dense terminal spikes. Spikes include two rows of overlapping, discoid sporangia. Isospores are round and featureless, and assignable to the genus Calamospora. While Bathurstia apparently originated from among the isotomously branching bilaterally symmetrical zosterophylls, the phylogenetic relationships of Bathurstia to known taxa is unclear, although some resemblance to Serrulacaulis, Barinophytaceae, and the Gosslingiaceae can be documented. Bathurstia denticulata is now one of the best known of early land plants, and contributes significantly to our understanding of zosterophylls and their role in Early Devonian vegetation.Key words: Bathurstia, zosterophyll, Devonian, Canada, Arctic, evolution.

The early land plants from the Armorican Massif: sedimentological and palynological considerations on age and environment

2010 ◽  
Vol 147 (6) ◽  
pp. 830-843 ◽  
Author(s):  
CHRISTINE STRULLU-DERRIEN ◽  
CÉLINE DUCASSOU ◽  
MICHEL BALLÈVRE ◽  
MARIE-PIERRE DABARD ◽  
PHILIPPE GERRIENNE ◽  
...  
Keyword(s):  
Lower Devonian ◽  
Age Determination ◽  
Land Plants ◽  
Variscan Belt ◽  
The South ◽  
History Of ◽  
Armorican Massif ◽  
First Time ◽  
Early Land ◽  
Emergence Event

AbstractThe Châteaupanne 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 Châteaupanne 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.

Early land plants

1985 ◽  
Vol 309 (1138) ◽  
pp. 197-200 ◽  
Keyword(s):  
New York ◽  
Land Plants ◽  
Early Devonian ◽  
Present Evidence ◽  
Rhynie Chert ◽  
Terrestrial Fungi ◽  
Early Land

After three decades of vigorous research on the Siluro-Devonian floras neither interest nor productivity is slackening. Some newer developments and comments on the two previous papers are listed here to highlight the varied disciplines and approaches that are being brought to bear on Silurian-early Devonian floras. (i) Banks (1981) reported wounds, probably inflicted by chewing microarthropods, in axes of Psilophyton dawsonii repaired by the form ation of a periderm . Unreported evidence indicates wounding and repair stimulated by piercing and sucking activity of other animals. These observations complement the work of Kevan et al. (1975) on arthropods and damage to plants that are found in the Rhynie Chert, and that of Shear et al . (1984) on a new terrestrial fauna from eastern New York. Interest in plant-anim al interrelationships will attract a new group of scholars to the study of Siluro-Devonian plants. Particularly im portant will be the m aceration of large quantities of rock. (ii) Stubblefield & Banks (1983) found oomycetous fungi within cells in the cellularly perm ineralized aerial axes of Psilophyton dawsonii . Rayner (1983) reported apparent fungal bodies in the spines on compression specimens of Sawdonia ornata . These reports supplem ent that by Kevan et al . (1975) on the fungi in the Rhynie Chert. Whether the fungi were parasitic or saprophytic, or were mycorrhizal as suggested by Pirozynski & Malloch (1975), is unclear on the basis of present evidence. Sherwood-Pike & Gray (1985) have isolated hyphae and spores of higher fungi from macerates of mid to late Silurian rocks from Gotland. Other fragments appear to be coprolites of arthropods that include fragments of hyphae. They suggest that fungi and microarthropods may have served as terrestrial decomposers during late Silurian. Pratt et al. (1978) reported septate fungi in earliest Silurian. These introductory works imply a productive future in the study of Siluro-Devonian terrestrial fungi.

scholarly journals Fertile Prototaxites taiti : a basal ascomycete with inoperculate, polysporous asci lacking croziers

2017 ◽  
Vol 373 (1739) ◽  
pp. 20170146 ◽  
Author(s):  
Rosmarie Honegger ◽  
Dianne Edwards ◽  
Lindsey Axe ◽  
Christine Strullu-Derrien
Keyword(s):  
Electron Microscopy ◽  
Type Species ◽  
Lower Devonian ◽  
Terrestrial Ecosystem ◽  
Tree Trunk ◽  
Thin Sections ◽  
Rhynie Chert ◽  
Thin Walled ◽  
Reproductive Characters ◽  
Scanning Electron

The affinities of Prototaxites have been debated ever since its fossils, some attaining tree-trunk proportions, were discovered in Canadian Lower Devonian rocks in 1859. Putative assignations include conifers, red and brown algae, liverworts and fungi (some lichenised). Detailed anatomical investigation led to the reconstruction of the type species, P. logani , as a giant sporophore (basidioma) of an agaricomycete (= holobasidiomycete), but evidence for its reproduction remained elusive. Tissues associated with P. taiti in the Rhynie chert plus charcoalified fragments from southern Britain are investigated here to describe the reproductive characters and hence affinities of Prototaxites . Thin sections and peels (Pragian Rhynie chert, Aberdeenshire) were examined using light and confocal microscopy; Přídolí and Lochkovian charcoalified samples (Welsh Borderland) were liberated from the rock and examined with scanning electron microscopy. Prototaxites taiti possessed a superficial hymenium comprising an epihymenial layer, delicate septate paraphyses, inoperculate polysporic asci lacking croziers and a subhymenial layer composed predominantly of thin-walled hyphae and occasional larger hyphae. Prototaxites taiti combines features of extant Taphrinomycotina (Neolectomycetes lacking croziers) and Pezizomycotina (epihymenial layer secreted by paraphyses) but is not an ancestor of the latter. Brief consideration is given to its nutrition and potential position in the phylogeny of the Ascomycota. This article is part of a discussion meeting issue ‘The Rhynie cherts: our earliest terrestrial ecosystem revisited’.

scholarly journals Ultrastructure of laevigate hilate spores in sporangia and spore masses from the Upper Silurian and Lower Devonian of the Welsh Borderland

1998 ◽  
Vol 353 (1378) ◽  
pp. 1983-2004 ◽  
Author(s):  
C. H. Wellman ◽  
D. Edwards ◽  
L. Axe
Keyword(s):  
Electron Microscope ◽  
Lower Devonian ◽  
Spore Wall ◽  
Land Plant ◽  
White Line ◽  
Early Land Plant ◽  
Wall Ultrastructure ◽  
Spore Mass ◽  
Upper Silurian ◽  
Early Land

Spore masses and isolated sporangia, containing laevigate hilate cryptospores attributable to the dispersed taxon Laevolancis divellomedia sensu lato , have been recovered on bulk maceration of Upper Silurian (Pridoli) and Lower Devonian (Lochkovian) deposits from the Welsh Borderland. Detailed morphological, anatomical and ultrastructural analysis, using light microscope, scanning electron microscope and transmission electron microscope techniques, reveals subtle differences between the specimens and they can be grouped into five distinct types. The different groups are distinguished principally by using sporangia–spore mass characteristics, presence or absence of extra–exosporal material and nature of spore–wall ultrastructure. Of the groups, one has a uniformly homogeneous exospore and the other four groups have a bilayered exospore. In the former the spores lack extra–exosporal material and occur in a discoidal sporangium. Of the bilayered groups, two have exospores of homogeneous composition but with the two layers differing in electron density. They occur in discoidal sporangia and spore masses and are distinguished on the presence or absence of extra–exosporal material and differences in the widths of the two layers. Finally, two bilayered groups possess a lamellate inner layer, but vary in presumed sporangial shape. Elongate sporangia have spores with concentric continuous lamellae, lacking further ultrastructure. In contrast, spores from a discoidal spore mass have white–line–centred, presumably tripartite, lamellae which are laterally discontinuous, overlapping and irregularly spaced. These findings, which suggest that morphologically similar spores were produced by a number of plant taxa, have important implications regarding the assessment of early land–plant diversity. The affinities of hilate cryptospore–producing plants are unknown and problematic, particularly as no extant non–angiosperm plants produce dyads, other than through meiotic irregularity, and spore–sporangial characters have no exact counterpart in coeval plants. Studies of specimens with in situ hilate cryptospores suggest that they derive from rhyniophytoids, i.e. plants that resemble the simplest of vascular plants but lack evidence of vascular tissue, although hilate cryptospore–containing examples show no axial branching. It might be argued, based on evidence from spore wall ultrastructure, that some of the plants have more in common with lycopsids and filicopsids than bryophytes, a surprising finding bearing in mind the stratigraphic distribution of hilate cryptospores–dyads and inferences that the producers were bryophyte–like. Detailed studies of wall structure in the hilate cryptospores permit consideration of spore wall development. It is suggested that extra–exosporal material derives from a tapetum and is thus produced by the diploid sporophyte. The white–line–centred lamellae in a single specimen provide the earliest evidence for the presence of such structures in early land plant spores and provide further evidence that sporopollenin deposition on such structures is the most primitive mode of sporopollenin deposition among land plants.

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