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Ordovician cephalopods from Western Gondwana are still poorly known and published data is in need of systematic and stratigraphical revision. In this work, the endocerid proterocameroceratid Protocyptendoceras from the Floian of the Eastern Cordillera of Argentina is revised using new material from La Ciénaga, 5 km upstream from Purmamarca. The species P. corvalani and P. teicherti are considered to be junior synonyms of P. fuenzalidae, which is redescribed in detail and reillustrated. Specimens preserve adapical parts of isolated siphuncles, related here to the presence of endocones in a posterior portion. Evidently P. fuenzalidae had a nektobenthic mode of life in a shallow water environment, oriented horizontally. Its palaeobiogeographical affinities are mainly with Floian proterocameroceratids from Eastern Gondwana, such as Anthoceras decorum and the related genera Lobendoceras, Ventroloboceras, and Notocycloceras.
Lingulate brachiopods from chalcedonites of Tremadoc age are redescribed based on new material from the Holy Cross Mountains, Poland. The fauna includes 18 species, of which Elliptoglossa polonica and Siphonotretella popovi are new. The enigmatic Orbiculoidea? subovalis Biernat is redescribed as a species of the recently erected aberrant paterulids Diencobolus Holmer, Popov, Koneva, and Bassett. The fauna includes also Acrotreta dissimilis (Biernat), ?Ditreta dividua Biernat, Semitreta maior Biernat, Eurytreta minor Biernat, Mamatia retracta (Popov), Orbithele ceratopygarum (Brøgger), Siphonobolus uralensis (Lermontova), Alichovia analogica Biernat, Pomeraniotreta sp., Akmolina sp., Rowellella sp., Acanthambonia sp. A, Acanthambonia? sp. B, Leptembolon cf. lingulaeformis (Mickwitz), and the earliest known species of Eoconulus. Most of the recorded lingulate species are endemic, but a significant number are now known also from eastern Kazakhstan and the South Urals, as well as from the Tremadoc of Sweden and Norway.
The studied brachiopod assemblages from the uppermost Lower Ordovician beds of Peru are of very low diversity and are among the northernmost known strata of that age in South America. They have been collected at the Carcel Puncco canyon of the Inambari River, near San Gabán in the easternmost Eastern Cordillera. Of the six species described, Euorthisina orthiformis and Paralenorthis immitatrix were already known from the Bolivian outcrops of the same Andean Eastern Cordillera; two species are new: Ahtiella zarelae Villas sp. nov. and Paralenorthis carlottoi Villas sp. nov. The new species of Ahtiella, of late Floian age, represent the oldest record of the genus characteristic of Celtic assemblages. During the early Mid Ordovician the genus migrated eastward from this region into the north margin of proto−Avalonia and after that, in Llanvirn times, into Baltica. During the early Llanvirn Ahtiella also migrated westward reaching the Precordillera Argentina region. Brachiopod faunal affinities suggest that there was a closer proximity of Avalonia with the Central Andean Basin, in similar temperate latitudes, than with the Southwestern European Platform, placed in very high latitude. Paralenorthis does not give any palaeogeographical signal, since it is known from all latitudes and palaeocontinents. Nevertheless, the occurrence of Euorthisina reinforces the Gondwanan signature of the region, since this genus spread during the Arenig throughout the middle latitude belt at the Gondwana margins, although it also colonised sub−polar latitudes, coinciding with the Llanvirn transgression over North Gondwana.
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