Geoffrey Playford

Bloodstream infections (BSIs) are a leading cause of healthcare-associated morbidity and mortality, with a significant portion being preventable. Despite t

Fossil assemblages preserved in nodules of the methane-seep deposits, recognized by Haig et al. (2022) in the lower Permian (Cisuralian, Sakmarian stage) of the Irwin Basin, include representatives of three ecosystems: seep, pelagic, and coastal plain. The seep biota, new to the Australian Permian, consists of small thickets with a framework of tubeworms, less common algal-like Tubiphytes, and problematica (? algae or sponges). Other components include microbial mats, macrophyte alga Litostroma (first report from Gondwana); foraminifers; sponges with siliceous monaxon spicules; a new group of small, lightly ornamented rostroconchs; microgastropods and rare larger types; ostracods and minute scolecodonts from polychaete jaws. Elements of the pelagic ecosystem are ammonoids (abundant in enclosing shale) and marine microphytoplankton. Probable vertebrate bone (possibly amphibians) and diverse spores and pollen from land plants come from the adjoining coastal plain. The surrounding mudstone lacks benthic macrofauna but includes an unusual assemblage of siliceous agglutinated foraminifers. The seeps were oases of high organic productivity on an otherwise barren muddy seafloor. The Holmwood Shale’s seep carbonates have close similarities to modern seep deposits in shallow-marine settings.

El conjunto diverso y bien conservado de esporas registrado en la Formación Lyall de la cuenca del río Clarke, en el norte de Queensland, incluye muchas especies del Mississippiano reportadas previamente en otras partes de Australia, a la vez que incluye un nuevo género y especie (Apricasporites cancellosus) y siete nuevas especies adicionales (Granulatisporites commutabilis, Anapiculatisporites radiatus, Camptotriletes inaequabilis, C. suggrandis, Convolutispora inreligata, Foveosporites magnus y Endosporites circumsaeptus). En términos de la zonación palinoestratigráfica existente de las sucesiones mississippianas de Australia, la palinoflora es claramente atribuible a la zona Anapiculatisporites largus del Viseano, reconocida por primera vez en la cuenca de Bonaparte (noroeste de Australia) y bien representada también en la cuenca de Drummond, en el centro-este de Queensland. Sin embargo, algunas especies constituyentes se conocen como componentes de la sucesiva Zona Grandispora maculosa (Viseano medio/final–Serpukhoviano temprano). Este estudio confirma las afinidades florísticas entre el este y el oeste de Gondwana durante el Mississippiano.

A diverse and abundant organic-walled microphytoplankton assemblage is reported from two measured sections of the Lower Devonian (Lochkovian) Ross Formation in Benton and Decatur counties, Tennessee. The palynoflora comprises 24 genera and 34 species of acritarchs, including one new genus and species (Caulissoma gordonii); and five genera and 11 species of prasinophyte phycomata (excluding Leiosphaeridia and Tasmanites). Other components include chitinozoans, miospores, and scolecodonts. This is the first Early Devonian acritarch/prasinophyte assemblage to be described from Tennessee, and is assigned a Lochkovian age based on marine invertebrate faunas, stratigraphic relationships, and the palynomorph assemblage. A high degree of similarity (67% commonality) exists between this palynoflora and that from the stratigraphic and age-equivalent Haragan and Bois d’Arc formations of Oklahoma. Appreciable numbers of the microphytoplankton taxa identified herein are common to the Haragan and Bois d’Arc formations and are, moreover, restricted to the Lochkovian and endemic to Laurentia. Additionally, a number of species are widely distributed and confined to the Early Devonian, and three species, Demorhethium lappaceum, Riculasphaera fissa, and Thysanoprobolus polykion – all cosmopolitan – are constrained to the Lochkovian. With increasing knowledge of Early Devonian palynofloras, the apparent degree of provincialism is progressively declining as seemingly endemic taxa are reported from more regions in both hemispheres. The Ross Formation sediments were deposited in a low-energy, offshore, normal marine environment, punctuated by intermittent episodes of shallow-water current and storm deposition.

The Woolaga Limestone Member—a thin, muddy, calcareous unit of the Holmwood Shale in the northern Perth Basin of Western Australia—contains a diverse and exceptionally well preserved palynoflora associated with a varied marine invertebrate fauna indicative of a Sakmarian (Early Permian/Cisuralian) age. Spores and pollen grains are overwhelmingly predominant in this palynomorph assemblage, with the identified taxa suggesting its assignment to either the Converrucosisporites confluens Zone or the succeeding Pseudoreticulatispora pseudoreticulata Zone of the currently recognized Western Australian Permian palynozonation. The spore-pollen content reveals substantial allochthonous contributions from the pteridophytic and gymnospermous (notably glossopterid) land vegetation into the marine depositional environment. Autochthonous or near-autochthonous components consist of algal microfossils (marine, fresh water, or brackish water) and rare scolecodonts (wholly marine).

This renewed palynological study of the Mount Johnstone Formation, at Balickera in the Hunter Valley region of New South Wales (eastern Australia), discloses a considerably more diverse palynoflora – termed the Grandispora maculosa Assemblage – than had been reported in 1968. Represented are some 51 species of palynomorphs, comprising 46 species of trilete spores (distributed among 27 genera), three species of monolete spores (three genera), one species of hilate spores, and a single algal-cyst species. The following species are newly instituted: Verrucosisporites adgeratus, V. johnstonense, V. pavimentatus, Anapiculatisporites robertsii, Convolutispora perplicata, Knoxisporites balickeraensis, Densoisporites argutus, Laevigatosporites demutabilis, and Latosporites durabilis. Quantitatively important and/or consistently represented species include Reticulatisporites magnidictyus (particularly), Punctatisporites spp., Verrucosisporites spp., Rattiganispora apiculata, Grandispora maculosa, Indotriradites kuttungensis, Velamisporites australiensis, Laevigatosporites demutabilis, and Psomospora detecta. The absence of marine palynomorphs supports the previously envisaged, predominantly fluvial deposition of the Mount Johnstone Formation. Key palynostratigraphic indices, in conjunction with absolute-age determinations obtained from sub- and suprajacent rocks, indicate that the G. maculosa palynoflora and its hosting Mount Johnstone strata are Mississippian – specifically middle–late Visean – age; this dating also applies to similarly palyniferous deposits in the northern Perth and Carnarvon basins of Western Australia. Beyond Eastern Gondwana, equivalents of the G. maculosa association have been reported from Western Gondwana (Brazil and Argentina in particular) and, to a lesser extent, from Northern Gondwana, thus attesting to its wide distribution and chronostratigraphic significance within the supercontinent and its distinctiveness vis-à- vis Euramerican regions.

A diverse and abundant organic-walled microphytoplankton assemblage, consisting of 49 species of acritarchs, prasinophyte phycomata and chitinozoans, was recovered from a 13.3 m-section of the Middle Devonian (Givetian) Arkona, Hungry Hollow and Widder formations at Hungry Hollow, Ontario, Canada. Close similarity exists between this assemblage and others described previously from the Givetian of North America. Marine palynofloras of comparable age from elsewhere in North America share between 59–96% of the species identified in the present assemblage, thus testifying to its stratigraphic-correlative applicability in a regional context. Species widely occurring in North America and typically Givetian (although not restricted therein) include: Arkonites bilixus, Cymatiosphaera canadense, Diexallophasis simplex, Duvernaysphaera angelae, D. tenuicingulata, Estiastra rhytidoa, Exochoderma arca, Gorgonisphaeridium inflatum, Hapsidopalla chela, Leiofusa pyrena, Muraticavea munifica, Oppilatala sparsa, Palacanthus ledanoisii, Polyedryxium ambitum, Staplinium cuboides, Tyligmasoma alargada, Uncinisphaera acantha, Veryhachium pastoris, Villosacapsula compta and V. rosendae. Palaeogeographically, Middle Devonian organic-walled microphytoplankton taxa display a conspicuous degree of cosmopolitanism, with many species shared with Laurasia (Laurentia, Avalonia, Baltica), Gondwana (principally Argentina, Ghana, Libya, Algerian Sahara, Western Australia) and Kazakhstan (northwestern China).

An abundant, diverse, and moderately well-preserved assemblage of organic-walled microphytoplankton is reported from two exposures of the Middle Devonian (Givetian) Gravel Point Formation at Little Traverse Bay, Michigan. The palynoflora consists of 13 prasinophyte and 19 acritarch species, together with some scolecodonts and chitinozoans. This is the first microphytoplankton assemblage to be described from the Middle Devonian of Michigan, and is clearly Givetian in age. It is closely comparable with, albeit less diverse than, Middle Devonian acritarch/prasinophyte assemblages reported from elsewhere in North America. Based on the diversity and abundance of the acritarch and prasinophyte taxa, along with evidence from marine faunas, the Gravel Point sediments accumulated in a normal, low-energy, offshore environment, with periodic regressions indicated by stromatoporoid–coral bioherms. Four of the acritarch species are restricted to the Middle Devonian of North America; the other specific components are typically, but not exclusively, Middle Devonian in age. Although some species are restricted to North America, others are cosmopolitan in distribution.