A low diversity Sinuites gastropod community from the Floian, Early Ordovician, of South Wales

A low diversity Sinuites-dominated gastropod community is described from the Floian, Arenig Series, of the Llangynog Inlier, southwest of Carmarthen, South Wales. The abundant material comes from shallow-water siltstone and mudstone beds of the Bolahaul Member of the Ogof Hên Formation. The locality has an exceptionally diverse mollusc-dominated fauna (63.5% of the fauna), with gastropods constituting 6% and tergomyans 1% and echinoderms, arthropods and other fauna making up the rest. Except for one rare tergomyan mollusc, identified as Carcassonnella cf. vizcainoi, other tergomyans are described elsewhere. Nearly half of all gastropod specimens are represented by Sinuites ramseyensis. Three of the five taxa described are new: Mimospira llangynogensis sp. nov., Catalanispira prima sp. nov., and Ceratopea? moridunensis sp. nov. The assemblage compares best with those of contemporaneous high-latitude peri-Gondwana areas. Early Ordovician species of Carcassonnella are typically found in France, Iberia, Czech Republic, and Morocco, while species of Mimospira are found in Germany and Czech Republic, but also in Baltica where the main radiation took place later. Two of the oldest occurrences of Mimospira are from Avalonian Wales (Carmarthenshire and Anglesey). Catalanispira occurs later in Baltica and Laurentia in the late Middle and early Late Ordovician, when taxa from these areas start to appear in Wales and vice versa. The presence of Ceratopea?, a genus typical of Laurentia, is at odds with the biogeographic distribution of faunas at this time. Part of the observed distribution pattern may be explained by different latitudinal position and facies depths of Avalonia compared to Armorica, Bohemia, and Morocco. The species described herein are amongst the first Floian taxa of these groups formally described from this area and add significantly to the global Floian record

A low diversity shallow water lingulid brachiopod-gastropod association from the Upper Ordovician of Kyrgyz Range

A low diversity association made up of the lingulid Tunisiglossa almalensis Popov and Mambetov, sp. nov. and the gastropod Ptychonema agyris Ebbestad, sp. nov. is described from the Upper Member of the Almaly Formation at Kyrgyz Range, North Tien Shan, Kyrgyzstan/Kazakhstan. The specimens co−occur in dense coquinas, made up of different sized individuals, deposited in a shallow water, intertidal, and storm driven depositional environment. The lingulid shells display a completely reduced dorsal pseudointerarea typical of Glossellinae, and the smooth shell lacking fine external granulation, radial or pitted ornament, a small ventral pseudointerarea, and no dorsal median ridge place it in the hitherto monotypic Tunisiglossa known previously only from the Lower Ordovician (Tremadocian) Sanrhar Formation of Libya. It compares with Ectenoglossa sorbulakensis that is widespread in the lower to middle Caradocian Anderken Formation of Chu−Ili Range in southern Kazakhstan. Gastropods of this age have not been reported earlier in Kyrgyzstan; neither can Ptychonema be compare with any taxon in the gastropod association earlier described from the contemporary Anderken Formation in Kazakhstan. Ptychonema is otherwise commonly associated with peri−Gondwana terranes, but the Late Ordovician dispersal pattern of the genus is unknown. Overall, however, the Upper Ordovician faunas of North Tien Shan show close similarities to contemporaneous faunas of the Chu−Ili terrane, which have strong biogeographic signatures linking them to the faunas of South and North China

Sedimentology of the Lower Ordovician (upper Tremadocian) Bjørkåsholmen Formation at Flagabro, southern Sweden

The Lower Ordovician Bjørkåsholmen Formation at Flagabro, Scania, southern Sweden, consists of a 0.8 m thick succession of carbonates with three siliciclastic mudstones, 5, 1 and 100 mm thick, intercalated in the central part of the unit. Carbonate and siliciclastic mudstone beds show both normal and inverse grading. The carbonates are mud-rich and subdivided into a mudstone, a wackestone and a packstone facies. Grain types in the carbonates are mostly shells and shell fragments of brachiopods and trilobites. The carbonate rocks are strongly bioturbated seen as in roundish burrows filled with mud and a clear cement; additionally, bioturbation is reflected in the random orientation of shells. The siliciclastic mudstones are subdivided into two facies; one contains large amounts of shells and is in part grain-supported, the other is matrix-dominated and laminated to massive. The succession reflects sedimentation on a low-inclined shelf equivalent to a mid-ramp to basinal setting. Most mud- and wackestones (facies 3 and 4) represent fair-weather sedimentation, and the intercalated wacke- and packstones (facies 4 and 5) represent concentration of shell debris during high-energy storm. The siliciclastic mudstones in the central part of the succession reflect deposition in a basinal setting. The entire Bjørkåsholmen Formation at Flagabro is equivalent to a lowstand of third (?) order without a well-developed internal cyclicity and is in that respect similar to the Bjørkåsholmen Formation of Öland, but different from the age-equivalent Norwegian sections