The teleost fish Paravinciguerria praecursor Arambourg, 1954 in the Cenomanian of north-eastern Sicily

Skeletal remains of the teleost fish species Paravinciguerria praecursor Arambourg, 1954 are described for the first time from the upper Cenomanian of the Peloritani and Nebrodi Mountains, north-eastern Sicily. Four partially articulated cranial fragments were collected from the bituminous shales of the Argille Varicolori succession outcropping near the towns of Floresta and Malvagna, in the province of Messina. The upper Cenomanian fossil fish-rich bituminous shales of the Peloritani and Nebrodi Mountains were deposited on a distal ramp along the North African continental shelf and represent sediments related to the Oceanic Anoxic Event 2. The finding of Paravinciguerria praecursor, previously described from the upper Cenomanian-lower Turonian deposits of Morocco and northern Italy, constitutes the eighteenth fish taxon to be described from the upper Cenomanian of north-eastern Sicily. The phylogenetic affinities of Paravinciguerria are discussed in detail in the present study. The assignment of this genus to one of the recognized protacanthopterygian subgroups is excluded here on the basis of anatomical features. Based on the structure of the upper jaw and hyobranchial apparatus, it is suggested that Paravinciguerria may be interpreted as a stem stomiiform, thereby representing the earliest member of this lineage. RIASSUNTO [Il teleosteo Paravinciguerria praecursor Arambourg, 1954 nel Cenomaniano della Sicilia nord-orientale] Resti scheletrici del teleosteo Paravinciguerria praecursor Arambourg, 1954 sono descritti per la prima volta nel Cenomaniano dei Monti Peloritani e dei Monti Nebrodi, nel settore nord-orientale della Sicilia. Sono stati esaminati quattro resti cranici parzialmente articolati raccolti negli scisti bituminosi delle Argille Varicolori affioranti nei pressi dei centri abitati di Floresta e Malvagna, in provincia di Messina. Gli scisti bituminosi ittiolitiferi tardo cenomaniani dei Monti Peloritani e dei Monti Nebrodi si originarono su una rampa distale lungo la piattaforma continentale nord-africana e costituiscono l’espressione sedimentaria del secondo evento anossico oceanico (OAE 2). Paravinciguerria praecursor, descritto in precedenza dai depositi del Cenomaniano superiore-Turoniano inferiore del Marocco e dell’Italia settentrionale, è il diciottesimo taxon ittico segnalato nei depositi tardo cenomaniani della Sicilia nord-orientale. Le possibili affinità filogenetiche di Paravinciguerria sono descritte in dettaglio. L’attribuzione di Paravinciguerria ad uno dei sottogruppi noti di protacantopterigi (=salmoniformi) è esclusa sulla base di evidenze anatomiche. La struttura e la conformazione delle ossa della mascella e dell’apparato io-branchiale evidenziano una certa affinità con gli stomiiformi, dei quali Paravinciguerria costituirebbe il più antico rappresentante. 2 Bollettino della Società Paleontologica Italiana, 50 (1), 2011 and eastern Sicily (Amodio-Morelli et al., 1976), also known as Argille Scagliose (Campisi, 1977), Complesso Antisicilide (Ogniben, 1969) and, more recently, Argille Scagliose Antisicilidi (Lentini et al., 2000). The black shales of the Argille Varicolori originated on a distal ramp located along the North African continental shelf (see Giunta & Nigro, 1999), possibly not far from the present Tunisia (Scopelliti et al., 2008). Micropaleontological analyses and isotope and organic geochemistry (Scopelliti et al., 2008; Rindone, 2010a, b) concur to indicate that the deposition of the organic-rich black shales occurred in a highly stressed paleobiotope, characterized by low oxygen and nutrient rich waters. More generally, the black shales of the Argille Varicolori represent the sedimentary expression of the Oceanic Anoxic Event 2 (OAE 2) that occurred close to the Cenomanian-Turonian boundary, leading to the world-wide sedimentation of organic-rich deposits (Schlanger & Jenkyns, 1976; Jenkyns, 1980). In Italy, deposits related to this event, also known as Bonarelli-level equivalents, are frequently exposed in southern Alps, Apennines and Sicily, often characterized by fossil fish remains (Bonarelli, 1891; Leonardi, 1965; Sorbini, 1976; Bizzarini & Coccioni, 1990; Avanzini & Luciani, 2001; Gomez et al., 2002). High resolution stratigraphic analyses suggest that the organic-rich black shales of the Argille Varicolori of north-eastern Sicily mostly record the lower portion of the OAE 2, dating back to the uppermost part of the Cenomanian (Scopelliti et al., 2008).