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Jurassic rhynchonellide brachiopods from the Jordan Valley are herein revised and new taxa are added to the faunal list. In this study of Jurassic rhynchonellides from Wadi Zarqa, northwestern Jordan, we recognize the following taxa: Eurysites rotundus, Cymatorhynchia quadriplicata, Daghanirhynchia triangulata, D. angulocostata, Pycnoria magna, Schizoria elongata, and Schizoria cf. intermedia. The following new taxa are described: Daghanirhynchia susanae sp. nov. and Amydroptychus markowitzi sp. nov. The Middle Jurassic Mughanniyya Formation of northwest Jordan is dominated by limestone beds. The sedimentary environment is interpreted as neritic, light, and nutrient−rich resulting in high faunal diversity. The high rhynchonellide endemism of this fauna is yet another confirmation of pronounced Middle Jurassic endemism along the southern Tethyan margin of the Ethiopian Province. Brachiopods of the Jordanian Mughanniyya Formation can be correlated with the fauna of the Aroussiah Formation in Sinai and the Zohar and Matmor formations in Southern Israel.
A new rhynchonellide brachiopod genus Antulanella is erected based on the examination of the external and internal morphologies and shell microstructure of “Rhynchonella pancici”, a common species in the Barremian shallow−water limestones of the Carpatho−Balkanides of eastern Serbia. The new genus is assigned to the subfamily Viarhynchiinae, family Tetrarhynchiidae. The shell of Antulanella is small to rarely medium−sized, subglobose, subcircular, fully costate, with hypothyrid rimmed foramen. The dorsal euseptoidum is much reduced. The dental plates are thin, ventrally divergent. The hinge plates are straight to ventrally convex. The crura possess widened distal ends, rarely raduliform or canaliform. The shell is composed of two calcitic layers. The secondary layer is fine fibrous, homogeneous built up of predominantly anisometric anvil−like fibres. Although data on the shell microstructure of post−Palaeozoic rhynchonellides are still incomplete, it is possible to distinguish two types of secondary layer: (i) fine fibrous typical of the superfamilies Rhynchonelloidea and Hemithiridoidea and (ii) coarse fibrous typical of the superfamilies Pugnacoidea, Wellerelloidea, and Norelloidea. The new genus Antulanella has a fine fibrous microstructure of the secondary layer, which is consistent with its allocation in the Hemithiridoidea. Antulanella pancici occurs in association with other brachiopods showing strong Peritethyan affinity and close resemblance to the Jura fauna (= Subtethyan fauna).
In contrast to dramatic losses of the Atrypida and Pentamerida at the Frasnian–Famennian boundary, the Rhynchonellida demonstrated relatively high rate of survival, and recolonized vacated benthic ecospace after the F–F extinction events. The Late Devonian evolution of rhynchonellid faunas from the East European Platform shows three distinctive periods of their mass appearance. High abundance of rhynchonellids is characteristic for early–middle Frasnian (Palmatolepis transitans–Pa. punctata zones) and early Famennian (Pa. crepida Zone). Invasion of taxonomically diverse and rich rhynchonellid faunas usually corresponds to the major transgressive episodes, whereas decline coincides with regressive conditions of the basin. Rhynchonellid assemblages were replaced in the late Frasnian (Late Pa. hassi–Pa. linguiformis zones) by theodossiid− and cyrtospiriferid−dominated assemblages, which occupied habitats in newly expanding marine environments. The extinction of theodossiids at the end of the Frasnian and the next transgressive episode possibly stimulated an expansion of rhynchonellids. The early Frasnian species Ripidiorhynchus livonicus (Buch, 1834), and the early Famennian R. huotinus (Verneuil, 1845) and R. griasicus (Nalivkin, 1934) are revised. Early Famennian species Paromoeopygma koscharica (Nalivkin, 1934) from the central region is redescribed. Ripidiorhynchus chencinensis sp. nov. from the latest Givetian of Poland, as well as Globulirhynchia minima sp. nov. from the late Frasnian of the central region of the Russia, are described.
The genus Dzieduszyckia is especially well represented and diverse in the Famennian strata of the Middle Atlas, Morocco. In this paper we re−study and re−illustrate the rich collection of Dzieduszyckia from Morocco, described by Henri and Genevive Termier, and originally referred to Halorella or Eoperegrinella. New data on the internal shell structure of D. crassicostata, D. intermedia, and D. tenuicostata indicate great intraspecific variability in morphology. The structure of crura of three studied species demonstrates that subfamily Dzieduszyckiinae is better placed within the family Halorellidae, instead of Peregrinellidae. Type specimens (lectotypes) of the three species were also selected. An analysis of the stable isotopes of carbon and oxygen of the shell material of Dzieduszyckia and carbonate sediment was used to investigate the presumed chemosynthetic nature of its paleoenvironments. The analyses of the Moroccan and Polish material do not show any signature of unusual environmental conditions: they fall in the range of the mean values of δ¹³C for the Late Devonian.
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