A new species of Saurichthys (Actinopterygii) from the Middle Triassic (Early Ladinian) 0f the Northern Grigna Mountain (Lombardy, Italy)

Rivista Italiana di Paleontologia e Stratigrafia (Impact Factor: 0.93). 11/2013; 119(3):287.

ABSTRACT A new species of Saurichthys is described. It comes from a Early Ladinian fossil-bearing bed lying in the middle-lower part of the Buchenstein Formation on the Northern Grigna southern slope (Pasturo, Lecco). This new species differs from the several other Middle Triassic species in the remarkable size (more than 130 cm in length), in the presence of a grid structure made by the dorsal elements of its vertebral column, and in the posteriorly enlarging endoskeletal elements of both dorsal and anal fins. Moreover, only two longitudinal scale rows distinguish this taxon; together with the grid structure of the dorsal vertebral column, this character was previously observed only in Norian species (Late Triassic). The early appearance of these features in a Ladinian species opens a new, serious discussion on the evolutionary trends of Saurichthys, which is a very important genus, inhabiting the seas and lakes all over the world from the latest Permian to the end of the Triassic.

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    ABSTRACT: The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian–Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian–Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, ‘Palaeopterygii’, ‘Subholostei’, Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but ‘palaeopterygians’ experienced a significant body size increase across the Guadalupian–Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian–Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, ‘palaeopterygians’, ‘subholosteans’) and a second one during the Middle Triassic (‘subholosteans’, neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a significant reduction in osteichthyan body size. Neopterygii, the clade that encompasses the vast majority of extant fishes, underwent another diversification phase in the Late Triassic. The Triassic radiation of Osteichthyes, predominantly of Actinopterygii, which only occurred after severe extinctions among Chondrichthyes during the Middle–Late Permian, resulted in a profound change within global fish communities, from chondrichthyan-rich faunas of the Permo-Carboniferous to typical Mesozoic and Cenozoic associations dominated by actinopterygians. This turnover was not sudden but followed a stepwise pattern, with leaps during extinction events.
    Biological Reviews 11/2014; · 9.79 Impact Factor
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    ABSTRACT: The Saurichthys card provides a short overview about the long slender ray-finned fossil actinopterygian saurichthyids comprising systematic paleontological profile, morphology and palaeoecology. Moreover, a stratigraphic and geographic distribution of all currrently known 64 valid Saurichythid species is given from the Late Permian to the Early Jurassic (per November 2014).
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    ABSTRACT: Diese Saurichthys-Übersichtskarte faßt in deutsch auf beiden Seiten kompakt alles wissenswerte zu den charakteristisch langestreckten Saurichtyhiden (Strahlenflosser) zusammen. Neben einem kurzen Steckbrief zur systematischen Paläontologie dieser Knochenfische, Morphologie und Paläoökologie wird die zeitliche und geographische Verbreitung aller derzeit bekannten 64 Saurichthyiden-Arten dokumentiert.


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May 31, 2014