The extinct catshark Pachyscyllium distans (Probst, 1879) (Elasmobranchii: Carcharhiniformes) in the Pliocene of the Mediterranean Sea

Abstract

<jats:p>Sharks assigned to the carcharhiniform family Scyliorhinidae account for about 160 extant species placed in 18 genera. Most living scyliorhinids are small- to medium- sized ground sharks provided with cat- like eyes and nasal barbels similar to whiskers; hence their vernacular name, "cat- sharks". Living catsharks mostly inhabit deep or rather deep waters of the warm and temperate seas worldwide, foraging on small fishes and inverterbates. In the present paper, we report on a lateral tooth of Scyliorhinidae collected from a clay pit at Certaldo (central Italy), where marine mudstones belonging to the famously fossiliferous Pliocene successions of Tuscany are exposed. This catshark specimen represents the second bona fide record of the extinct premontreine species<jats:italic> Pachyscyllium distans</jats:italic> in the Pliocene of the Mediterranean Sea, as well as the geologically youngest confirmed occurrence of this species worldwide. In the Mediterranean Pliocene,<jats:italic> P. distans</jats:italic> thus coexisted with the similar but distinct species<jats:italic> Pachyscyllium dachiardii</jats:italic>. After having been widespread in Northern Atlantic, Paratethyan, and Mediterranean waters in Miocene times,<jats:italic> P. distans</jats:italic> became confined to the Mediterranean Sea during the Pliocene. Therefore, similar to what has recently been suggested for<jats:italic> P. dachiardii</jats:italic>, we hypothesise that the range of<jats:italic> P. distans</jats:italic> contracted southward as colder conditions took hold in the Northern Hemisphere. The eventual extinction of<jats:italic> P. distans</jats:italic> might be related to the first cooling episode that significantly affected the Mediterranean biota around 3 Ma.</jats:p>

Remarkable multicuspid teeth in a new elusive skate (Chondrichthyes, Rajiformes) from the Mediterranean Pliocene

“…Supporting this interpretation, the elasmobranch assemblage described herein takes its place besides remains of marine invertebrates and vertebrates that are typical of shallow and warm waters, such as Metaxytherium subapenninum, a tropical and coastal-estuarine form which likely shared the environmental preferences of modern sirenians (Sorbi et al 2012). The palaeoenvironmental scenario evoked by the mudstone succession exposed at Certaldo differs from that of Arcille by its relatively deeper, offshore setting, as also suggested by the scanty elasmobranch assemblage (Collareta et al 2020d). Faunal elements shared between Arcille and Certaldo include Rostroraja olisiponensis, which is thought to be ancestral to the extant white ray Rostroraja alba (Bor et al 2012); the latter currently inhabits the shelfal environments of the Mediterranean Sea between about 40 and 400 m depth (Serena 2005).…”

“…The Valdelsa Basin is filled with some 1000 m of Mio-Pleistocene sediments (Benvenuti et al 2014) that are home to rich and diverse fossil vertebrate assemblages comprised of both terrestrial and marine forms (Collareta et al 2020a, and references therein). The succession exposed at the Certaldo quarry consists of massive, greyish-bluish, shelfal mudstones that crop out along an artificial cliff (Collareta et al 2020d). Fossils are particularly abundant in a ca.…”

“…25-cm-thick interval that also feature rare invertebrate burrows. The invertebrate assemblage is comprised of bivalve and gastropod molluscs (mostly venerids and vermetids, including the extinct large-sized clam Pelecyora brocchii and the worm snail Thylacodes arenarius) and a single species of acorn barnacle (Concavus concavus), whereas the vertebrate assemblage consists of a few teeth of elasmobranchs (assigned to Megascyliorhinus miocaenicus, Pachyscyllium distans and Rostroraja olisiponensis) and indeterminate otoliths (Collareta et al 2020d). The elasmobranch remains, including one of the specimens described herein (i.e.…”

The upper Miocene Deurne Member of the Diest Formation revisited: unexpected results from the study of a large temporary outcrop near Antwerp International Airport, Belgium

“…In addition, the occurrence of some species might also be the result of evolutionary trends during the Miocene rather than reflecting paleo-environmental differences. Shark genera that originated in the Paleogene, such as the basking shark Keasius and the catshark Pachyscyllium, became extinct in the North Sea Basin towards the upper Miocene (see Reinecke et al, 2015;Collareta et al, 2020), which might explain their presence/absence in Units 1 and 2 respectively. This might be the other way around for 'new' species whose origin is situated in the (upper) Miocene.…”

Another thermophilic "Miocene survivor" from the Italian Pliocene: A geologically young occurrence of the pelagic eagle ray Aetobatus in the Euro-Mediterranean region

“…Vertebrate finds from these Tuscan Pliocene successions include marine mammals (both odontocete and mysticete cetaceans as well as sea cows and rarer pinnipeds), sea turtles, bony and cartilaginous fishes, and even terrestrial forms (e.g., DOMINICI et al, 2018, and references therein). In spite of a long history of palaeontological research, discoveries of new taxa or somewhat "exotic" vertebrate specimens are still relatively frequent from the Tuscan Pliocene marine and paralic sediments (e.g., SPADINI & MANGANELLI, 2015;COLLARETA et al, 2017aCOLLARETA et al, , 2017bCOLLARETA et al, , 2018COLLARETA et al, , 2020aCOLLARETA et al, , 2020cCOLLARETA et al, , 2020dCOLLARETA et al, , 2021BIA-NUCCI et al, 2019;MANGANELLI & SPADINI, 2019).…”