A fossiliferous horizon containing Claraia is reported for the first time 8 m above the base of the Servino Fm. in the we¬stern Orobic Alps (Lecco, Lombardy). The specimens have a broad morphological variability which mostly concerns the sculpture, and thus several morphospecies can be recognized [C. cf. aurita (Hauer, 1850), C. cf. bittneri Ichikawa, 1958, C. tesidea (Leonardi, 1929), C. intermedia (Bittner, 1901), C. radialis (Leonardi, 1929), C. cf. clarai (Emmrich, 1844)]. These taxa have mostly been classified into C. in¬termedia by applying a species-population concept. The Claraia horizon of the Orobic Alps can be correlated with the transitional layers between the C. clarai and C. aurita subzo¬nes of the Werfen Fm. (Siusi Member) in the Dolomites. Thus, in this area, the first Triassic marine transgression with age-diagnostic fossils of the Servino Fm. may have an age ranging from the latest Griesbachian to the early Dienerian.

First report of Claraia in the Servino Formation (Lower Triassic) of the western Orobic Alps, Italy.

POSENATO, Renato;
1996

Abstract

A fossiliferous horizon containing Claraia is reported for the first time 8 m above the base of the Servino Fm. in the we¬stern Orobic Alps (Lecco, Lombardy). The specimens have a broad morphological variability which mostly concerns the sculpture, and thus several morphospecies can be recognized [C. cf. aurita (Hauer, 1850), C. cf. bittneri Ichikawa, 1958, C. tesidea (Leonardi, 1929), C. intermedia (Bittner, 1901), C. radialis (Leonardi, 1929), C. cf. clarai (Emmrich, 1844)]. These taxa have mostly been classified into C. in¬termedia by applying a species-population concept. The Claraia horizon of the Orobic Alps can be correlated with the transitional layers between the C. clarai and C. aurita subzo¬nes of the Werfen Fm. (Siusi Member) in the Dolomites. Thus, in this area, the first Triassic marine transgression with age-diagnostic fossils of the Servino Fm. may have an age ranging from the latest Griesbachian to the early Dienerian.
Posenato, Renato; Sciunnach, D; Garzanti, E.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11392/1207433
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