Eocene cartilaginous fishes from Bolca Lagerstätte, Italy

The goals of the current project are to analyze the morphology, taxonomy, and systematic of Eocene cartilaginous fishes (holocephali, sharks, skates and rays) from one of the most famous palaeontological sites of the world, the Bolca Konservat-Lagerstätte, in Italy. Eocene chondrichthyans from Bolca represent an ideal case study to analyze the morphology, relationships and ecological structures of marine communities since this fauna is predominantly represented by articulated skeletons and dates back about 16 Ma after the end-Cretaceous extinction event, corresponding to a period of profound global especially climatic changes. Although in the last four centuries several studies contribute to increase our knowledge of the extraordinary palaeobiodiversity of the Bolca Konservat-Lagerstätte, chondrichthyans have been largely ignored in palaeobiological studies employing modern, state-of-art methodological approaches up to now. The project will focus on the following questions: (1) What is the taxonomic composition and systematic position of cartilaginous fish assemblages of the Pesciara and Monte Postale sites? (2) What are their phylogenetic relationships with living and fossil representatives? (3) What are the diversity and diversification patterns of Eocene chondrichthyans? (4) What are the faunal relationships and similarities of the Eocene Bolca cartilaginous fishes with other coeval assemblages? To answer these questions, which are of utmost importance to understand the evolutionary patterns of this unique assemblage, we will employ a multidisciplinary approach. Morphological studies of Eocene cartilaginous fishes of Bolca will be the starting point of the project. Subsequently, modern morphological and molecular methods within an evolutionary framework employing sophisticated statistical approaches will allow us to reconstruct evolutionary and diversity dynamics, in order to better understand chondrichthyan palaeobiological patterns. Consequently, this project will improve our understanding about part of the evolutionary history of one of the most significant aquatic vertebrate groups in deep-time, which mostly are top predators in marine food webs, the chondrichthyans, after the K/Pg boundary event during a prolonged phase of biotic recoveryand also during a time of major climatic changes. Simultaneously, the project also will be an important contribution to the knowledge of one of the most important palaeontological sites of the world, contributing to promote the cultural heritage of Europe. The project will be conducted by Dr. Giuseppe Marramà, an experienced vertebrate palaeontologist, will in co-operation with Prof. Dr. J. Kriwet, who is head of the Evolutionary Morphology Research Group at the Department of Palaeontology of the University of Vienna, Austria and Prof. Dr. G. Naylor from the College of Charleston, USA, who is a specialist in molecular genetics of sharks, rays, and skates.

The goals of the current project were to analyze the morphology, taxonomy, and systematic of Eocene cartilaginous fishes (holocephali, sharks, skates and rays) from one of the most famous palaeontological sites of the world, the Bolca Konservat-Lagerstätte, in Italy. Eocene chondrichthyans from Bolca represent an ideal case study to analyze the morphology, relationships and ecological structures of the marine communities since this fauna is predominantly represented by articulated skeletons and dates back about 16 Ma after the end-Cretaceous extinction event, corresponding to a period of profound global changes. Although in the last four centuries several studies contribute to increase our knowledge of the extraordinary palaeobiodiversity of the Bolca Konservat-Lagerstätte, chondrichthyans have been largely ignored in palaeobiological studies employing modern, state-of-art methodological approaches up to now. The project focused on the following questions: 1) What is the taxonomic and systematic composition of Bolca chondrichthyans? 2) What are their relationships with living and extinct cartilaginous fishes? 3) What is their palaeoecological and palaeoenvironmental significance? A multidisciplinary approach was employed to accomplish the main goals of this project. Morphological studies of Eocene cartilaginous fishes of Bolca were the starting point of the project. Subsequently, phylogenetic morphological and molecular methods allowed us to reconstruct the evolutionary dynamics, in order to better understand chondrichthyan palaeobiological patterns. In terms of taxonomy and systematics, we re-evaluated the anatomy and phylogenetic relationships of several taxa belonging to a variety of sharks, inlcuding Eogaleus bolcensis (Carcharhinidae), and Brachicarcharias lerichei (Odontaspididae), and batoids, including electric rays Titanonarke molini and T. megapterygia (Torpediniformes), Tethytrygon muricatus (Dasyatidae), Lessiniabatis aenigmatica (Myliobatiformes inc. sedis), Promyliobatis gazolai (Myliobatidae), etc. The taxonomic composition of the Monte Bolca elasmobranch fauna is very different from those of other coeval Tethyan and Boreal localities, suggesting the these differences are mostly related to the different environmental and ecological conditions and depositional context. It is clear that the shallow waters of Monte Bolca represented a unique refuge area during the early Eocene (about 50 million years ago) in the Tethys Ocean for bony and cartilaginous fishes. This project improved our understanding about part of the evolutionary history of one of the most significant aquatic vertebrate groups, which mostly are top predators in food chains, the chondrichthyans, after the K/Pg boundary event during a prolonged phase of biotic recovery. Simultaneously, the project was also an important contribution to the knowledge of one of the most important palaeontological sites of the world, contributing to promote the cultural heritage of Europe.