Diversification trajectories and paleobiogeography of Neogene chondrichthyans in Europe

Despite the rich fossil record of Neogene chondrichthyans (chimaeras, sharks, rays and skates) from Europe, little is known about the macroevolutionary processes that generated their current diversity and geographical distribution. We compiled 4,419 Neogene occurrences comprising 102 genera, 41 families and 12 orders from four European regions (Atlantic, Mediterranean, North Sea and Paratethys) and evaluated their diversification trajectories and paleobiogeographic patterns. In all analysed regions, we found that the generic richness increased during the early Miocene, then decreased sharply during the middle Miocene in the Paratethys and moderately during the late Miocene and Pliocene in the Mediterranean and North seas. Origination rates display the most significant pulses in the early Miocene in all regions. Extinction rate pulses varied across regions, with the Paratethys displaying the most significant pulses during the late Miocene and the Mediterranean and North seas during the late Miocene and early Pliocene. Overall, up to 27% and 56% of the European Neogene genera are now globally and regionally extinct, respectively. The observed pulses of origination and extinction in the different regions coincide with warming and cooling events that occurred during the Neogene globally and regionally. Our study reveals complex diversity dynamics of Neogene chondrichthyans from Europe and their distinct biogeographic composition despite the multiple marine passages that connected the different marine regions during this time.