A NEW SPECIES OF SAURICHTHYS (ACTINOPTERYGII) FROM THE MIDDLE TRIASSIC (EARLY LADINIAN) OF THE NORTHERN GRIGNA MOUNTAIN (LOMBARDY, ITALY)

Abstract

A new species of Saurichthys is described. It comes from an 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.