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The five species of genus EuthacanthusPowrie, 1864 are reduced to two species on morphological and stratigraphical evidence. Euthacanthus macnicoliPowrie, 1864 and Euthacanthus grandisPowrie, 1870 are here synonymised in the type species E. macnicoliPowrie, 1864. In a previous article, Euthacanthus gracilisPowrie, 1870 and Euthacanthus elegansPowrie, 1870 were combined in the species E. gracilis, and the fifth species, Euthacanthus curtusPowrie, 1870, was reassigned to Uraniacanthus curtus (Powrie, 1870). In this work, we give an in-depth study of the full range of morphological and histological structure of scales over the body of E. macnicoli, as well as of fin spine structure. Our study reveals new features of E. macnicoli, including a large ornamented dorsal sclerotic bone, ornament on the branchiostegal plates, a separate series of gular rays, calcified cartilage forming the jaws, and a postbranchial protruding spinose plate rather than the flat prepectoral plate previously described.
Based on the morphology of the aperture and internal plaits or folds, the Nerineoidea Zittel, 1873 are subdivided into seven families: the Pseudonerineidae Pchelintsev, 1965, Ceritellidae Wenz, 1940, Nerinellidae Pchelintsev, 1960, Eunerineidae n. fam. (new family that includes the Nerineidae Zittel, 1873 (pars) and the Diptyxidae Bouchet & Rocroi, 2005) the Ptygmatididae Pchelintsev, 1960, Nerineidae and Itieriidae Cossmann, 1896. The internal plaits of the Nerineoidea had different functions: the columellar plaits subdivided the columellar muscle into strands, which allowed portions of the foot to be moved individually. A tubelike space delimited by the parietal and palatal plaits is compared with the pallial caecum or posterior mantle chamber of heterobranchs and served the respiration. Waste from both mantle chambers was expelled through a subsutural notch, which is the common feature of the Nerineoidea. The Nerineoidea were shell draggers and probably deposit feeders with a semi- infaunal mode of life. The “Lower Heterobranchia” represented by the Streptacidoidea Knight, 1931, Nerineoidea and Acteonelloidea Akopjan, 1976 cluster outside the Euthyneura Knight, 1931. The Acteonelloidea, the second group of large Heterobranchia are related to the Nerineoidea and cannot be part of the Acteonoidea. The extinction of the Eunerineidae n. fam., the Ptygmatididae and Ceritellidae in the Late Cenomanian was caused by a general warming in low latitudes. The Acteonellidae genus TrochactaeonMeek, 1863 replaced the extinct Eunerineidae n. fam. ecologically in shallow marine soft-bottom environments and became extinct itself in the Lower Campanian due to the general cooling. In the Caribbean palaeobiological province, the endemic Nerineoidea genus PlesioptygmatisBoese, 1906 extended stratigraphically to the basal Late Maastrichtian. Acteonella d'Orbigny, 1842 and the endemic Acteonellidae genus MexicotrochactaeonAkopjan, 1972 ranged upwards into the Late Maastrichtian.
KEYWORDS: Charophyta, Biogéography, Eocene, Oligocene, Ebro foreland Basin, Paris Basin, Hampshire Basin, Rhine Basin, new species, biogéographie, Éocène, Oligocène, bassin d'avant-pays de l'Ebre, bassin de Paris, bassin du Hampshire, bassin du Rhin, espèce nouvelle
Eighteen charophyte species are documented from the Upper Eocene-Lower Oligocene transitional and terrestrial facies on the eastern Ebro Basin. The charophyte assemblage is composed of one Eurasian species, Lychnothamnus stockmansii (Grambast, 1957), fourteen species distributed throughout Europe (Harrisichara vasiformis form vasiformis-tuberculataFeist-Castel, 1977, Harrisichara lineataGrambast, 1957, Harrisichara tuberculata (Lyell, 1826), Nitellopsis (Tectochara) merianii (Al. Braun ex Unger, 1852), Lychnothamnus vectensis (Groves, 1926), L. grambastii (Feist-Castel, 1971), L. major (Grambast & Paul, 1965), Gyrogona caelata (Reid & Groves, 1921), Psilochara aff. acutaGrambast & Paul, 1965, Chara aff. antennataGrambast, 1958, C. rhenanaSchwarz & Griessemer, 1994, C. microceraGrambast & Paul, 1965, Sphaerochara labellataFeist & Ringeade, 1977, Lamprothamnium sp.) and three species restricted to the Ebro Basin during the interval considered (Nodosochara jorbaeChoi, 1989, Lychnothamnus longusChoi, 1989 and Chara artesica n. sp., a new species defined by very small gyrogonites and showing a reduced number of convolutions. A biogeographic analysis of the assemblage studied suggests that during Late Eocene and Early Oligocene, Europe represented a bioprovince characterised by the regular and abundant occurrence of species belonging to the lineages of Harrisichara vasiformis-tuberculata and Lychnothamnus stockmansii-major, along with Nitellopsis (Tectochara) merianii and Chara microcera in all European basins. Charophyte distribution in this bioprovince displays a north to south polarity with a reduction in the number of species. Ecological features related to the dynamics of the Ebro basin, such as the high terrigenous input in freshwater wetlands during the Upper Eocene-Oligocene, are in contrast to the sea-connected and carbonatic systems of the Paris, Hampshire and Rhine basins. This resulted in low species richness in the Ebro Basin. These biogeographic patterns have implications in the use of some European biozones, which should be of use only at a regional scale.
The rodents from the Upper Messinian deposits of Moncucco Torinese (MCC) (Piedmont, NW Italy) are described. Stratigraphic considerations indicate that the fossiliferous deposits exposed at MCC date back to the post-evaporitic phase of the Messinian Salinity Crisis (5.40–5.33 Ma). Thirteen rodent taxa belonging to the families Cricetidae Fischer, 1817, Muridae Illiger, 1811, Gliridae Thomas, 1897 and Sciuridae Fischer, 1817 are recognized based on 1177 teeth. The occurrence of Centralomys benericettii (De Giuli, 1989), Paraethomys meini (Michaux, 1969) and Apodemus gudruna van de Weerd, 1976 allows to compare MCC with other latest Messinian localities of northern Italy, such as Brisighella and Verduno. The rodent assemblages described herein and, more particularly, the taxa A. gudrunae, Muscardinus vireti Hugueney & Mein, 1965 and Glirulus lissiensis Hugueney & Mein, 1965, suggest that MCC can be referred to the Late Turolian (MN13). Moreover, the presence of taxa commonly found in Pliocene localities of western and central Europe (Occitanomys brailloniMichaux, 1969, Micromys bendai van de Weerd, 1979, Neocricetodon magnus (Fahlbusch, 1969) and Sciurus warthaeSulimski, 1964) indicates that some typical Ruscinian elements were already present at the end of the Miocene at least in southern-central Europe. The rodent assemblages of MCC also include Apodemus atavus Heller, 1936, Eliomys aff. intermedius Friant, 1953, Glis minorKowalski, 1956, and Pliopetaurista pliocaenica (Depéret, 1897). Overall, the fossil assemblages documented in this paper remarkably expand our knowledge on the Late Miocene rodent communities of Italy, also providing useful data for the interpretation of biogeographic relationships between western and eastern Europe at the end of the Messinian.
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