Monica Pondrelli (1), carlo corradini (2), claudia SPalletta (3), luca SiMonetto (4), Maria criStina Perri (3), Maria G. corriGa (5), corrado Venturini (3) & HanS Peter ScHönlaub (6)
he Carnic Alps represent the best exposed Paleozoic succession within the Alpine domain being fossiliferous, mostly non-metamorphic and largely complete. This study focuses on the area around Mt. Pizzul, because the bedrocks record well the basin dynamics and most of the units are conodont bearing. Our aims were to contribute to the procedure of formalization of the lithostratigraphic units and to understand the depositional and deformation history of the study area. The area has been mapped, tectonic overprint constrained and the successions described, measured and dated. As a second-order aim, we discuss these data to infer the relations with other parts of the Carnic basin and to recognize the global controls on sedimentation. The depositional evolution can be sketched as follows: pre-Hirnantian ramp-type margin; Hirnantian glacioeustatic-related deposits and unconformity; pelagic deposition in a ramp-type margin (Přídolí–Eifelian); slope formation and differentiation in buildup, foreslope and pelagic environments (Eifelian–Frasnian); transgression and reef drowning (Frasnian–Visean); probable subaerial exposures likely during in uppermost Famennian and Visean times; and turbidite deposition (Visean). Global controls or deposits suggesting a global control are documented, including the Boda Event, the Hirnantian glaciation, the Middle Devonian reef growth, the Kačák Event, and the high-frequency sea-level fluctuations around the Devonian–Carboniferous boundary. The drowning of the buildups here and elsewhere in the Carnic Alps started during the Frasnian, unlike observed globally. This suggests that local tectonics lead to progressive deepening up to the transition to turbidite deposition
A B S T R A C TThe first asellote isopod from the fossil record is described here as Fornicaris calligarisi Wilson and Selden, n. gen. and sp. The two specimens, both probably males, showing dorsal morphology, come from loose material of the Dolomia di Forni Formation in the bed of the Tagliamento River below the town of Forni di Sotto, Udine Province, Friuli Venezia Giulia Autonomous Region, northeastern Italy. The Dolomia di Forni Formation is Triassic (Norian) in age, and the fossils date from approximately 210-215 Ma. Characters such as narrow, elongate eye stalks, tiny uropods, and enlarged first pereionite (found in terminal males) place the fossil within the Paramunnidae. Parsimony analysis using TNT placed the fossil within the Austrosignum-Munnogonium species complex. The robust pereiopods with hooked tips, elongate and robust carpus and propodus of pereiopod I, axial compression of the pereion, and the large size of the fossils (>2× related extant taxa) are features particular to the fossil genus and species.KEY WORDS: Dolomia di Forni Formation, Janiroidea, Paramunnidae DOI: 10.1163/1937240X-00002387 INTRODUCTIONIsopods are common inhabitants of marine, freshwater, and humid terrestrial environments, but not plentiful as fossils. In particular, while fossil isopods are known from numerous suborders (Hessler, 1969;Etter, 2014;Jones et al., 2014;Klompmaker et al., 2014;Broly et al., 2015), until now, no members of the large and diverse suborder Asellota, comprising marine and freshwater forms, have been described from the fossil record. Here, we describe a new genus and species of asellote isopod based on two specimens from the Upper Triassic (Norian) of the Carnic Prealps (Friuli, northeastern Italy).A cursory examination of these specimens suggested they showed ventral views of the cycloid Halicyne von Meyer, 1844, which is not uncommon in the Triassic of Europe (von Meyer, 1847;Trümpi, 1957;Merki, 1961; Gall and Grauvogel, 1967;Gall, 1971). Even though the ventral appendages of cycloids are poorly preserved, what is known about them is that they have fewer appendages, with fewer podomeres, than the fossil described here, no well-developed anterior grasping appendage. A single, large carapace is always visible (Dzik, 2008). Further investigation proved that the animals from Friuli are isopod crustaceans.Although isopods appear frequently among Mesozoic strata (Etter, 2014), some groups apparently do not fossilize * Corresponding author; e-mail: paulselden@mac.com well and have been slow to be reported in the literature. The terrestrial isopods described prior to Broly et al. (2015) were known only from Cenozoic facies, although Lins et al. (2012), using molecular dating techniques on modern taxa, asserted that the Oniscidea and other isopod suborders appeared prior to the Mesozoic, perhaps as early as Carboniferous or Late Devonian. The suborder Asellota may fossilize poorly, owing to their thin cuticle, and were currently unreported in the fossil literature, despite Lins et al. (2012) estimating the...
The Rio Malinfier West section in the central Carnic Alps provides important data on the evolution of the Lochkovian (Lower Devonian) sedimentary basins of the Variscan belt. An exposure of about 100 m comprises five lithostratigraphic units (Alticola, Rauchkofel, Nölbling, La Valute and Findenig formations) spanning in age from the latest Silurian to the Early Devonian. The complex structural setting of the section results from a main fault dividing the succession in two separate segments. A precise lithological characterization was carried on at a macro-and micro-scale. Macrofauna includes, among others, abundant cephalopods and crinoids (loboliths). The biostratigraphic assignment to the uppermost Silurian-lowermost Devonian (Lochkovian) was possible based on a moderately abundant conodont fauna, that provided thirty-two taxa belonging to thirteen genera, among which the new species Zieglerodina schoenlaubi. The Rio Malinfier West section testifies that a differentiation between shallow and deep water parts of the Devonian basin was already present during Lochkovian times, prior to the establishment of the conditions enabling the colonization of the well-known upper Lower-Middle Devonian reef buildings.
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