A harvestman (Arachnida: Opiliones) from the Early Devonian Rhynie cherts, Aberdeenshire, Scotland

A harvestman (Arachnida: Opiliones) is described from the Early Devonian (Pragian) Rhynie cherts, Aberdeenshire, Scotland. Eophalangium sheari gen. et sp. nov. is the oldest known harvestman. The material includes both males and a female preserving, respectively, a cuticle-lined penis and ovipositor within the opisthosoma. Both these structures are of essentially modern appearance. The Rhynie fossils also show tracheae which are, again, very similar to those of living harvestmen. This is the oldest unequivocal record of arachnid tracheal respiration and indicates that E. sheari was terrestrial. An annulate, setose ovipositor in the female suggests that it can be excluded from the clades Dyspnoi and Laniatores, in which the ovipositor lacks such annulations. However, the penis shows evidence of two muscles, a feature of uncertain polarity seen in modern Troguloidea (Dyspnoi). The presence of median eyes and long legs excludes Cyphophthalmi, and thus, E. sheari is tentatively referred to the suborder Eupnoi. Therefore, this remarkable material is implicitly a crown-group harvestman and is one of the oldest known crown-group chelicerates. It also suggests an extraordinary degree of morphological stasis within the eupnoid line, with the Devonian forms differing little in gross morphology – and perhaps in reproductive behaviour – from their modern counterparts.Peer Reviewe

Fossil arbuscular mycorrhizae from the Early Devonian

The 400 million-year-old Rhynie chert has provided a wealth of information not only of early land plants, but also of the fungi that inhabited this paleoecosystem. In this paper we report the first unequivocal evidence of arbuscules in an endomycorrhizal symbiosis. A new genus, Glomites, is characterized by extraradical, aseptate hyphae with a two-parted wall, and an intraradical, highly branched network of thin-walled hyphae. Hyphal branches produce terminal, elongate-globose multilayered spores that lack a basal septum. Other hyphae penetrate cell walls and form arbuscules. Arbuscules are morphologically identical to those of living arbuscular mycorrhizae (AM) in consisting of a basal trunk and highly dichotomous distal branches that form a bush-like tuft. Arbuscules are confined to a narrow band of specialized thinwalled cells in the outer cortex that continue to be meristematic. Features of the fossil biotroph are compared with those of extant arbuscular mycorrhizae. Although interpretations regarding the evolution of mycorrhizal mutualisms continue to be speculative, the demonstration of arbuscules in the Early Devonian indicates that nutrient transfer is an ancient phenomenon that may have been in existence when plants invaded the land

Perithecial ascomycetes from the 400 million year old Rhynie chert: an example of ancestral polymorphism

We describe a perithecial, pleomorphic ascomycetous fungus from the Early Devonian (400 mya) Rhynie chert; the fungus occurs in the cortex just beneath the epidermis of aerial stems and rhizomes of the vascular plant Asteroxylon. Perithecia are nearly spherical with a short, ostiolate neck that extends into a substomatal chamber of the host plant; periphyses line the inner surface of the ostiole. The ascocarp wall is multilayered and formed of septate hyphae; extending from the inner surface are elongate asci interspersed with delicate paraphyses. Asci appear to be unitunicate and contain up to 16 smooth, uniseriate-biseriate ascospores. The method of ascospore liberation is unknown; however, the tip of the ascus is characterized by a narrow, slightly elevated circular collar. Ascospores appear 1–5 celled, and germination is from one end of the spore. Also present along the stems and interspersed among the perithecia are acervuli of conidiophores that are interpreted as the anamorph of the fungus. Conidiogenesis is thallic, basipetal and probably of the holoarthric-type; arthrospores are cube-shaped. Some perithecia contain mycoparasites in the form of hyphae and thick-walled spores of various sizes. The structure and morphology of the fossil fungus is compared with modern ascomycetes that produce perithecial ascocarps, and characters that define the fungus are considered in the context of ascomycete phylogeny

Triassic Leech Cocoon From Antarctica Contains Fossil Bell Animal

This is the publisher's version of this article, which has been shared with permission. The article is also available from: http://dx.doi.org/10.1073/pnas.1218879109Our understanding of the evolution of life on Earth is limited by the imperfection of the fossil record. One reason for this imperfect record is that organisms without hard parts, such as bones, shells, and wood, have a very low potential to enter the fossil record. Occasionally, however, exceptional fossil deposits that preserve soft-bodied organisms provide a rare glimpse of the true biodiversity during past periods of Earth history. We here present an extraordinary find of a fossil ciliate that is encased inside the wall layer of a more than 200 Ma leech cocoon from Antarctica. The microfossil consists of a helically contractile stalk that attaches to a main body with a peristomial feeding apparatus and a large Cshaped macronucleus. It agrees in every aspect with the living bell animals, such as Vorticella. Vorticellids and similar peritrichs are vital constituents of aquatic ecosystems worldwide, but so far have lacked any fossil record. This discovery offers a glimpse of ancient soft-bodied protozoan biotas, and also highlights the potential of clitellate cocoons as microscopic “conservation traps” comparable to amber

Systematics and Paleoecology of a New Peltaspermalean Seed Fern From the Triassic Polar Vegetation of Gondwana

This is the publisher's version, which has been shared with permission. The original version may be found at: http://dx.doi.org/10.1017/S0954102011000241A new Triassic seed fern is described on the basis of a large collection of well-preserved plant compressions from the Upper Triassic of Mt. Falla, Queen Alexandra Range, central Transantarctic Mountains. The foliage is simple entire-margined to pinnatifid to partly pinnate and is assigned to Dejerseya lobata (Jones et de Jersey) Herbst emend. nov. Associated with these leaves occur two new reproductive structures. The ovulate organ Matatiella dejerseyi sp. nov. is a lax, conelike structure with primarily shield-shaped megasporophylls that are dissected into three to four narrow lobes, each bearing a single recurved, naked ovule. The pollen organ Townrovia polaris sp. nov. consists of a slender axis arising from a covered reproductive bud, bearing pinnately arranged, stalked, elongate receptacles each with ;20 unilocular, clavate pollen sacs; the pollen is bisaccate nontaeniate with an irregular longitudinal sulcus and coarse saccus endoreticulations, corresponding to the dispersed pollen Falcisporites australis. Similar pollen grains occur in the micropylar canals of seed cuticles of M. dejerseyi. Co-occurrence data indicate that the three taxa are probably different organs from one plant species. This new seed fern is assigned to the Matatiellaceae, which we place into the Peltaspermales because of structural similarities with vegetative and reproductive organs of other peltaspermalean seed ferns. It appears that several Triassic Gondwanan plant fossil taxa of currently uncertain affinities—such as Pachydermophyllum, Linguifolium, Carpolithus mackayi, and Andersonia—may belong to the Matatiellaceae as well. We suggest that the matatiellacean peltasperms were opportunistic, early successional plants that were particularly successful in colonizing stressed wetland environments in polar latitudes during the Triassic

An evidence-based 3D reconstruction of Asteroxylon mackiei, the most complex plant preserved from the Rhynie chert.

Funder: Biotechnology and Biological Sciences Research CouncilThe Early Devonian Rhynie chert preserves the earliest terrestrial ecosystem and informs our understanding of early life on land. However, our knowledge of the 3D structure, and development of these plants is still rudimentary. Here we used digital 3D reconstruction techniques to produce the first well-evidenced reconstruction of the structure and development of the rooting system of the lycopsid Asteroxylon mackiei, the most complex plant in the Rhynie chert. The reconstruction reveals the organisation of the three distinct axis types - leafy shoot axes, root-bearing axes, and rooting axes - in the body plan. Combining this reconstruction with developmental data from fossilised meristems, we demonstrate that the A. mackiei rooting axis - a transitional lycophyte organ between the rootless ancestral state and true roots - developed from root-bearing axes by anisotomous dichotomy. Our discovery demonstrates how this unique organ developed and highlights the value of evidence-based reconstructions for understanding the development and evolution of the first complex vascular plants on Earth

Acaulosporoid glomeromycotan spores with a germination shield from the 400-million-year-old Rhynie chert

This is the publisher's version, which is being shared with permission. The original version is available from: http://dx.doi.org/10.1007/s11557-008-0573-1Scutellosporites devonicus from the Early Devonian Rhynie chert is the only fossil glomeromycotan spore taxon known to produce a germination shield. This paper describes a second type of glomeromycotan spore with a germination shield from the Rhynie chert. In contrast to S. devonicus, however, these spores are acaulosporoid and develop laterally in the neck of the sporiferous saccule. Germination shield morphology varies, from plate-like with single or double lobes to tongue-shaped structures usually with infolded margins that are distally fringed or palmate. Spore walls are complex and appear to be constructed of at least three wall groups, the outermost of which includes the remains of the saccule. The complement of features displayed by the fossils suggests a relationship with the extant genera Ambispora, Otospora, Acaulospora or Archaeospora, but which of these is the closest extant relative cannot be determined. The acaulosporoid spores from the Rhynie chert document that this spore type was in existence already ∼400 mya, and thus contribute to a more complete understanding of the evolutionary history of the Glomeromycota. This discovery pushes back the evolutionary origin of all main glomeromycotan groups, revealing that they had evolved before rooted land plants had emerged

A reappraisal of Mississippian (Tournaisian and Visean) adpression floras from central and northwestern Europe

Mississippian plant fossils are generally rare, and in central and northwestern Europe especially Tournaisian to middle Visean fossil floras are restricted to isolated occurrences. While sphenophytes and lycophytes generally are represented by only a few widespread and long-ranging taxa such as Archaeocalamites radiatus, Sphenophyllum tenerrimum and several species of Lepidodendropsis and Lepidodendron, Visean floras in particular show a remarkably high diversity of fern-like foliage, including filiform types (Rhodea, Diplotmema), forms with bipartite fronds (Sphenopteridium, Diplopteridium, Spathulopteris, Archaeopteridium), others with monopodial, pinnate fronds (Anisopteris, Fryopsis) and still others characterized by several-times pinnate fronds (e.g., Adiantites, Triphyllopteris, Sphenopteris, Neuropteris). Most of these leaf types have been interpreted as belonging to early seed ferns, whereas true ferns seem to have been rare or lacking in impression/compression floras. In the upper Visean, two types of plant assemblages can be distinguished, i.e., the northern Kohlenkalk-type and the south-eastern Kulm-type assemblage. Although several compression/impression taxa have been revised in recent years to provide a more uniform classification, additional parameters such as different modes of preservation and imprecise information on stratigraphic age hamper detailed interregional comparisons of Mississippian floras.Pflanzenfossilien aus dem Mississippium sind generell selten. Floren aus dem Tournaisium bis Mittel-Viseum hat man in Zentral- und Nordwesteuropa nur in wenigen isolierten Lokalitäten gefunden. Diese Floren sind von Sphenophyten und Lycophyten (z.B. Archaeocalamites radiatus, Sphenophyllum tenerrimum sowie Taxa aus den Gattungen Lepidodendropsis und Lepidodendron) dominiert, welche alle eine weite geographische Verbreitung und lange geologische Reichweite aufweisen. Demgegenüber weisen die Floren des jüngeren Viseum eine bemerkenswerte Diversität an Pteridophyllen auf. Neben filiformen Wedeln (Rhodea, Diplotmema) kennt man aus diesen Floren unterschiedliche Typen einfach gegabelter (Sphenopteridium, Diplopteridium, Spathulopteris, Archaeopteridium) sowie einfach (Anisopteris, Fryopsis) und mehrfach gefiederter Wedel (e.g., Adiantites, Triphyllopteris, Sphenopteris, Neuropteris). Der überwiegende Teil dieser Wedel wird den frühen Samenfarnen zugeordnet; Nachweise von echten Farnen sind ausgesprochen selten. Im oberen Viseum können zwei unterschiedliche Pflanzenassoziationen unterschieden werden: eine nördliche Kohlenkalk-Assoziation und eine südöstliche Kulm-Assoziation. Obwohl mehrere Pflanzentaxa des Mississippiums in Europa in den vergangenen Jahren revidiert worden sind, bleiben doch überregionale Vergleiche sowie die Erstellung einer einheitlichen Klassifikation durch die z.T. großen Unterschiede in der Erhaltung der Fossilien aus den einzelnen Fundpunkten sowie durch Probleme bei der Bestimmung des exakten stratigraphischen Alters der jeweiligen Fundschichten schwierig