Tortonian teleost otoliths from northern Italy: taxonomic synthesis and stratigraphic significance

Chien-Hsiang Lin,Angela Girone,Rotislav Brzobohatý,Dirk Nolf

doi:10.5852/ejt.2017.322

Abstract

The Tortonian fish otoliths of northern Italy have been studied for more than a century and represent one of the best known otolith-based teleost faunas in the Miocene of the Mediterranean Basin. Yet with the growing knowledge on Recent otoliths, an updated taxonomic overview of this fauna is needed. Moreover, new material from hemipelagic Tortonian marls sampled at nine localities is described herein, revealing 109 taxa of which 88 are recognised at species level. Four of these are new: Coryphaenoides biobtusus sp. nov., “Merluccius” rattazzii sp. nov., Neobythites auriculatus sp. nov. and Lesueurigobius stironensis sp. nov. The compilation of previously studied and newly acquired material revealed a total of 118 nominal Tortonian species. At generic level, the fauna is characterised by many modern forms; more than 90% can be assigned to present day genera. At species level, however, more than half of the represented taxa are extinct. Based on the fossil otolith record, the Tortonian fauna of the Mediterranean is most similar to that of the Langhian (Badenian) of the Central Paratethys by sharing many extinct Miocene species, but it is also very close to that of the Pliocene Mediterranean, by sharing many modern Atlantic-Mediterranean forms. The Tortonian fauna is further characterised by many species that are apparently confined to the upper Miocene, resulting in a unique combination of its taxonomic composition.

Highlights

In northern Italy, Tortonian deposits yielding fish otolith are known and have been studied for more than a century (Bassoli 1906; Anfossi & Mosna 1969a, 1969b; Robba 1970; Anfossi & Mosna 1971; Nolf & Steurbaut 1983; Girone et al 2010; Lin et al 2015; Lin 2016), revealing an otolith-based fish fauna of about 100 taxa
Several additional Tortonian otolith specimens deposited at the Museo Geologico, University of Torino, Italy (MGUT) are included: Pterothrissus umbonatus (MGUT 11529), Pseudophichthys splendens (MGUT 11563), Coelorinchus maximus (MGUT 11575), Pycnocraspedum cetonaense (MGUT 11557), Hoplostethus lawleyi (MGUT 11541, 11551), Hoplostethus praemediterraneus (MGUT 11555), Holocentrus weileri (MGUT 11575), Argyrosomus regius (MGUT 11540), Owstonia neogenica (MGUT 11563)
The otolith-based Tortonian fauna of the Mediterranean contains 118 nominal species (Table 2), with a considerably high proportion that can be assigned to modern genera (108 out of 118, ca 91.5%)

Summary

Introduction

In northern Italy, Tortonian deposits yielding fish otolith are known and have been studied for more than a century (Bassoli 1906; Anfossi & Mosna 1969a, 1969b; Robba 1970; Anfossi & Mosna 1971; Nolf & Steurbaut 1983; Girone et al 2010; Lin et al 2015; Lin 2016), revealing an otolith-based fish fauna of about 100 taxa. The fauna from this area became the best known in the Mediterranean Basin. This fauna is characterised by a high number of modern genera, grouping both extant and fossil species (Lin et al 2015)

Methods

Results

Conclusion