Diversity, palaeoecology and palaeoenvironmental significance of the Eocene chondrichthyan assemblages of the Bolca Lagerstätte, Italy

Autor(en)

Giuseppe Marramà, Giorgio Carnevale, Jürgen Kriwet

Abstrakt

In the last few years, the anatomy, taxonomy and relationships of the cartilaginous fish taxa of the two main fossiliferous deposits of the Bolca Lagerstätte, the Pesciara and Monte Postale sites, have been extensively discussed in a series of papers, resulting in a complete systematic revision of this neglected component of the Eocene Tethyan ichthyofauna. Here, we present a comprehensive overview of the diversity, palaeoecology and palaeoenvironmental significance of the two chondrichthyan assemblages of the Pesciara and Monte Postale sites. Overall, the assemblages include 14 species-level taxa of sharks (Lamniformes and Carcharhiniformes) and batoids (Torpediniformes, Rhinopristiformes, Myliobatiformes, Platyrhinidae, Zanobatidae), as well as of a single putative chimaeriform. Although the Pesciara and Monte Postale sites are characterized by eight chondrichthyan taxa each, the taxonomic compositions are distinctly different reflecting the dissimilarities in the overall composition of their fish assemblages. Palaeoecological interpretations and habitat preferences of the two chondrichthyan assemblages are consistent with the palaeoenvironmental settings that were previously hypothesized based on sedimentological, palaeontological and geochemical evidence. The two chondrichthyan associations appear to be constituted by ecologically vicariant taxa, being both characterized by a predominance of benthic species with durophagous/cancritrophic feeding mode (mostly batoids), followed by piscivores (especially selachians). A third group, the soft-prey feeders (e.g., torpediniforms) appear to be exclusive of the Monte Postale assemblage. There are no large opportunistic eurytrophic predators (diet mostly based on fishes and other vertebrates) or microphagous filter feeders (diet based mainly on plankton) in these assemblages, possibly because of the absence of specific food items or because the palaeoenvironmental conditions of the shallow water palaeobiotopes precluded the access to these groups. Based on the bathymetric distribution of extant chondrichthyan relatives, our analysis suggests that both the Pesciara and Monte Postale palaeobiotopes were likely characterized by depths reaching 40-50 meters, thereby supporting the assumption of a shallow water inner shelf scenario. In conclusion, taxonomic composition, habitat preferences and palaeobathymetric analyses support the hypothesis that both the assemblages occupied tropical marine shallow waters of the inner portion of the Lessini Shelf, which were surrounded by coral reefs.

Organisation(en)

Institut für Paläontologie

Externe Organisation(en)

Università degli Studi di Torino

Band

21

Seiten

57-57

Anzahl der Seiten

1

Publikationsdatum

06-2021

Peer-reviewed

Ja

ÖFOS 2012

105118 Paläontologie

Sustainable Development Goals

SDG 14 – Leben unter Wasser

Link zum Portal

https://ucris.univie.ac.at/portal/de/publications/diversity-palaeoecology-and-palaeoenvironmental-significance-of-the-eocene-chondrichthyan-assemblages-of-the-bolca-lagerstatte-italy(2f13b861-3ea5-46e6-8ea8-5433d6f996f5).html