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Aulotortus ? eotriasicus, n.sp., un nuovo foraminifero del Trias medio (Anisico) delle Dinaridi ed Ellenidi

Rettori, Roberto
Published in Bollettino dellà Società paleontologica italiana. 1994, vol. 33, no. 1, p. 43-49
Abstract Aulotortus ? eotriasicus, n. sp., is a new name for an involutinid Middle Triassic (Anisian) foraminifer of the Dinarids previously described from the same locality of Bosnia•Herzegovina (material J-P. Cadet, sample KDD8) by Bronnimann et al. (1973a) and assigned to Involutina sinuosa pragsoides (Oberhauser, 1964). The analysed material is from the Middle Anisian (Pelsonian) carbonate reefal facies of the Dinarids (Prekarstic Subzone). The new species is common in a grey organogenous limestone, sometimes dolomitic, which is overlain by the Ammonitico rosso limestone of the Han Bulog facies (Trinodosus Zone). Aulotortus ? eotriasicus, n. sp., is associated with some index microfossils of the Anisian, among which the typical pelsonian foraminiferal assemblage of Meandrospira dinarica, Pilammina densa, Pilamminella grandis. From a taxonomie point of view, the morphological characters of the unpillared involutinid Aulotortus ? eotriasicus, n. sp., do not allow to assign the species to the pillared Upper Triassic to Jurassic (Cretaceous?) genus Involutina Terquem. The here proposed attribution to Aulotortus Weynschenk remains doubtful, as the recrystallized test does not exhibit any lamellar structure, which, according to Piller (1978), remains the only adequate feature to distinguish the unpillared triassic involutinid genera Aulotortus Weynschenk and Triadodiscus Piller. For the larger dimensions, the new species has been tentatively attributed to Aulotortus. Aulotortus ? eotriasicus n. sp., has also to be distinguished from the Middle (Ladinian) to Upper Triassic lenticular species pragsoides, to which it was assigned by Bronnimann et al., 1973. The new species essentially differs from «Involutina sinuosa pragsoides» (= Aulotortus pragsoides) in having a narrower tubular second chamber, a larger number of whorls, and in having a lenticular test subangular in outline. As far as the distribution of the new species is concerned, Aulotortus ? eotriasicus, n. sp., has also been recorded from the Middle Anisian (Pelsonian) of the hellenid locality of Hydra (Rettori et al., in press), where the Pelsonian age of the foraminiferal assemblage (Aulotortus ? eotriasicus, n. sp., Meandrospira dinarica, Pilammina densa, Pilamminella grandis etc.) has been established on the basis of Conodonts (Angiolini et al., 1992).
Keywords ForaminiferidaMiddle TriassicPelsonianNew speciesBiostratigraphyDinaridsHellenids
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Research group Sedimentology, Biostratigraphy and Micropaleontology
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ZANINETTI, Louisette, RETTORI, Roberto, MARTINI, Rossana. Aulotortus ? eotriasicus, n.sp., un nuovo foraminifero del Trias medio (Anisico) delle Dinaridi ed Ellenidi. In: Bollettino dellà Società paleontologica italiana, 1994, vol. 33, n° 1, p. 43-49. https://archive-ouverte.unige.ch/unige:4771

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Deposited on : 2010-01-15

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