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More than 150 Ordovician and Early Silurian brachiopod species have been assigned to the genus Platystrophia King, 1850 mainly on the basis of their Spirifer-like shell exteriors. King’s concept of the genus was based on Platystrophia biforata King, which is not conspecific with Terebratulites biforatus Schlotheim, traditionally regarded as the type species of Platystrophia. Porambonites costatus Pander, 1830 is formally proposed as the type species of the genus to replace P. biforata; the latter is considered to be a nomen dubium. In our revised diagnosis, Platystrophia is restricted to a group of Arenig to upper Caradoc species from Baltica and Avalonia, whereas the Ashgill and lower Silurian taxa of these regions, hitherto assigned to Platystrophia, are placed in the new genus Neoplatystrophia. Platystrophia ponderosa Foerste, 1909 from the Upper Ordovician of North America is proposed as the type species of a new genus Vinlandostrophia. Two new species, Platystrophia baltica and Platystrophia pogrebovi from the Llanvirn–Caradoc of the East Baltic are also described.

Shape analysis of a large sample of the thecideid brachiopod Thecidellina from the Pliocene and Pleistocene rocks on the Caribbean island of Curaçao highlights asymmetry within the population. However, the 30 analysed specimens display a lack of a consistent asymmetry. The brachiopods were cemented to substrates by a cicatrix, accommodated by a change in shell structure. The plastic morphology of Thecidellina may have been due to overcrowding and competition for resources on limited substrates. [ABSTRACT FROM AUTHOR]

Since the early 2000s, the discovery of fossils and their collection from the Fezouata Shale has accelerated; enabling us to understand the faunas more thoroughly. The brachiopod fauna has not been investigated for the past 50 years, and we present here the results of our recent studies. From the material (c. 350 samples), 30 species were identified and assigned to 23 genera. Among these, one new genus (Tinzoulinorthis) and four new species (Wosekella maghribi, Rafanoglossa inversa, Orbithele tazagurta, Lacunites punctum) are erected; one taxon is recognized at the family level. The fauna described from the upper Tremadocian horizons is more diverse than those in the Floian. The former is characterized by a high γ‐diversity, although at the horizon level the α‐diversity is low to medium. This fauna is typical of high‐energy, shallow‐water, unstable environmental conditions, in which long‐lived communities were prevented from developing into climax communities, and the succession of opportunists were regularly smothered in situ and killed by storm deposits. Multivariate analyses of the faunas indicate that the Tremadocian fauna, characterized by many endemic taxa, has closer affinities with faunas from peri‐Gondwanan terranes, in particular Bohemia. The Tremadocian Fezouata fauna is very rich in taxon first occurrences, which, coupled with a high γ‐diversity, suggest that it may have been a diversity hub. In contrast, the Floian Fezouata fauna not only shows stronger connections with Bohemia and the Montagne Noire, it also has links with the South Urals and Baltica, reflecting the changing Early Ordovician palaeogeography. [ABSTRACT FROM AUTHOR]

The disciplines of palaeontology and stratigraphy are inextricably linked and it is not a surprise that fossils and their collections played and continue to play a major role in recognizing and correlating rock successions. Geological systems have traditionally been identified by their lithologies and fossil content. Collections in state and other recognized institutions are key references to the passage of geological time and organic evolution but are also fundamental for the correlation of rock successions. Stratigraphically-arranged displays, common in the nineteenth and early twentieth centuries have been commonly morphed into galleries show-casing the evolution of life. Nevertheless, chronostratigraphic units, such as systems, series and stages defined on their fossil content ultimately proved an unstable concept. Stages were recognized by the presence of groups of fossils initially in a type area and elsewhere on the occurrence of some or all of those in the type sections. Global Boundary Stratotype Sections and Points (GSSPs) are where rock meets time, at a point defined in a section and provide a more stable way to define and correlate rock successions. [ABSTRACT FROM AUTHOR]

The Late Ordovician Mass Extinction was the earliest of the 'big' five extinction events and the earliest to affect the trajectory of metazoan life. Two phases have been identified near the start of the Hirnantian period and in the middle. It was a massive taxonomic extinction, a weak phylogenetic extinction and a relatively benign ecological extinction. A rapid cooling, triggering a major ice age that reduced the temperature of surface waters, prompted a drop in sea level of some 100 m and introduced toxic bottom waters onto the shelves. These symptoms of more fundamental planetary processes have been associated with a range of factors with an underlying driver identified as volcanicity. Volcanic eruptions, and other products, may have extended back in time to at least the Sandbian and early Katian, suggesting the extinctions were more protracted and influential than hitherto documented. [ABSTRACT FROM AUTHOR]

We challenge the prevailing view that the end‐Permian extinction impeded the Triassic evolution of sponges. Here, we report a deep‐water community dominated by abundant keratose sponges in the lowest Triassic strata from Southwest China. The sponge fossils occur as dark elliptical imprints in mudstone with distinct oscula on their tops. The structure of preserved fibers suggests closest affinity with the extant Dictyoceratida, an aspiculate demosponge. The exceptional preservation plays a crucial role in retaining their exquisite structures. Sedimentary, taphonomic, pyrite framboid, and trace elemental analyses indicate that the sponges proliferated in an oxygen‐poor habitat, demonstrating the high tolerance of sponges to severe conditions. Sponge proliferation is a signal of environmental upheaval but they also stabilized the ecosystem, driving the first phase of biotic recovery after the end‐Permian extinction. [ABSTRACT FROM AUTHOR]

An unusually rich and diverse suite of virgianid brachiopods, hitherto poorly known, is systematically described here for the first time from the Ordovician–Silurian boundary interval (late Katian – Aeronian) of North Greenland. The Late Ordovician virgianids comprise typical taxa of the warm‐water Tcherskidium fauna (e.g. Tcherskidium tenuicostatum, Proconchidium schleyi, Holorhynchus giganteus and Deloprosopus dawesi sp. nov.). Among the early Silurian taxa, Virgiana hursti sp. nov. occurs as abundant shell beds, similar to other congeneric species in Laurentia, but has somewhat larger internal skeletal structures, albeit not as extravagantly developed as in the late Katian virgianids; Borealoides balderi gen. et sp. nov. shows extreme thickening of the shell wall and internal structures, approaching the extravagant calcification of Katian virgianids. The highly distinctive mid‐Aeronian stricklandioid brachiopod genus, Kulumbella, characterized by a shell with criss‐cross (divaricate) ribbing, also occurs in North Greenland, represented by K. heimdali sp. nov., which has the largest and most strongly biconvex shells for the genus. Palaeogeographically, the Late Ordovician virgianid fauna of Laurentia was highly distinct, confined to the low–mid tropical latitudes north of the palaeoequator. In comparison, the early Silurian (Rhuddanian) Virgiana and some related taxa in Laurentia spanned the tropics of both hemispheres, forming extensive shell beds in carbonate basins, although Borealis and Borealoides gen. nov. remained confined largely to the northern hemisphere, suggesting a certain level of provincialism extending into the earliest Silurian. A palaeoecological preference for warm‐water carbonate settings would explain the unusual abundance and richness of the virgianid faunas in North Greenland. [ABSTRACT FROM AUTHOR]

Despite its small areal extent, the island of Ireland exposes eight Caledonian tectonic terranes; six of them contain Ordovician brachiopod assemblages. These terranes record the early phases and destruction of the Iapetus Ocean through the occurrence of latitude-sensitive brachiopod faunas during the Middle Ordovician and early Late Ordovician; more cosmopolitan faunas characterized the later Ordovician. [ABSTRACT FROM AUTHOR]