A new basal actinopterygian fish from the Late Ladinian of Monte San Giorgio (Canton Ticino, Switzerland)
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A new basal actinopterygian fish from the Late Ladinian of Monte San Giorgio (Canton Ticino, Switzerland) Cristina Lombardo
Received: 31 August 2012 / Accepted: 22 March 2013 / Published online: 16 November 2013 Ó Swiss Geological Society 2013
Abstract A new taxon of Late Ladinian basal actinopterygian is described on the basis of a single specimen from the Meride Limestone (Kalkschieferzone) of Meride (Canton Ticino, Switzerland). The species is characterized by a single plate-like branchiostegal, a suboperculum larger than the operculum, a maxillary fixed and posteriorly expanded, a large and rectangular dermopterotic and a large triangular dermosphenotic; the scales are rectangular to rhomboidal, the lepidotrichia of median fins are segmented from their base and the caudal fin shows epaxial rays. These features resemble the condition of the Redfieldiiformes, a freshwater fish group, whose presence in Europe is still controversial, owing to poor preservation of specimens found so far. Keywords Actinopterygians Middle Triassic Monte San Giorgio Lagersta¨tte Taxonomy Palaeobiogeography Abbreviations MCSNL Museo Cantonale di Storia Naturale di Lugano (Switzerland) ant Antorbital b.f. Basal fulcra br Branchiostegal ray cl Cleithrum dpt Dermopterotic dsph Dermosphenotic
Editorial Handling: M. J. Benton & D. Marty. C. Lombardo (&) Dipartimento di Scienze della Terra ‘‘A. Desio’’, Universita` degli Studi di Milano, via Mangiagalli 34, 20133 Milan, Italy e-mail: [email protected]
d.s. exsc f.f fr gu ifo lmd mx na op pa pcl pl pop pr pt rmd ro scl sop
Dorsal scute Exstrascapular Fringing fulcra Frontal Gular Infraorbital bone Left mandibula Maxilla Nasal Operculum Parietal Postcleithrum Pit line Preoperculum Post-rostral Posttemporal Right mandibula Rostral bone Supracleithrum Suboperculum
1 Introduction The Middle Triassic of the Monte San Giorgio area, located between Switzerland and Italy (Fig. 1), has been known for more than 150 years for its rich fossiliferous levels, which yielded among the most important marine vertebrate faunas of the Mesozoic (Kuhn-Schnyder 1974; Tintori et al. 1985; Bu¨rgin et al. 1989; Tintori 1990a; Sander 1989; Lombardo and Tintori 2004; Tintori and Lombardo 2007). On the basis of these finds, the Swiss side of Monte San Giorgio has been included in the WHL UNESCO in 2003, followed in 2010 by the Italian part in
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C. Lombardo
Fig. 1 Geographical and geological setting of the Monte San Giorgio area. The stout black line indicates the Formazione di Besano outcrops. The star indicates the position of the Meride site (Val Mara D: 45°530 32.1700 N, 8°560 44.3500 E). Modified after Lombardo (2002)
order to protect an outstanding and unique paleontological Lagersta¨tte. In particular, the uppermost levels of Meride Limestone, the Kalkschieferzone (=KSZ), dating from the Late Ladinian, turned out to be very interesting for their faunal composition, and also for paleoenvironmental studies (Lombardo and Tintori 2002; Stockar 2010; Stockar and Renesto 2011; Stockar et al. 20
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