Abstract

The study of the origin of evolutionary novelties (novel traits, feeding modes, behaviours, ecological niches, etc) has regarded a number of taxa experimenting new body plans that allowed to occupy new habitats and exploit new trophic resources. In marine realm, colonization of pelagic environments by marine fishes occurred recurrently through time. Stingrays (Myliobatiformes) are a diverse clade of batoid fishes, commonly known to possess venomous tail stings. Current hypotheses suggest that stingrays experimented a transition from benthic to pelagic/benthopelagic habitat coupled with a transition from a non-durophagous diet to extreme durophagy. However, there are no works detailing on macroevolutionary patterns to understand how and when habitat shift and feeding specialization arose along their evolutionary history. A new exquisitely preserved fossil stingray from the world-famous Eocene Konservat-Lagerstätte of Bolca (Italy) exhibits a unique mosaic of plesiomorphic features of the rajobenthic ecomorph, and derived traits of the aquilopelagic taxa that helps to clarify the evolutionary origin of durophagy and pelagic lifestyle in stingrays. A scenario of early evolution of the aquilopelagic ecomorph is proposed based on new data, and the possible adaptive meaning of the observed evolutionary changes is discussed. The body plan of †Dasyomyliobatis thomyorkei gen. et sp. nov. is intermediate between the rajobenthic and more derived aquilopelagic stingrays, supporting its stem phylogenetic position and the hypothesis that the aquilopelagic body plan arose in association with the evolution of durophagy and pelagic lifestyle from a benthic, soft-prey feeder ancestor.