First occurrence of a †coccolepidid fish (?Chondrostei: †Coccolepididae) from the Upper Lias (Toarcian, Early Jurassic) of southern Germany

Abstract

The non-neopterygian group †Coccolepididae, a moderately diverse predominantly freshwater family, remains an imperfectly known Mesozoic group of actinopterygians, currently classified within Chondrostei based on the presence of several acipenseriform synapomorphies. Coccolepidids first appear during the Early Jurassic in marine sediments, although their fossils are poorly known from this time, and none have yet been described from the Toarcian (Upper Lias). Here, we describe a new genus and species of coccolepidid fish, †Toarcocephalus morlok gen. et sp. nov. from the Lower Jurassic (Toarcian) Posidonienschiefer Formation of Holzmaden in southern Germany. †Toarcocephalus morlok is diagnosed by a unique combination of characters including a shallow lower jaw with a massive angular, opercle and subopercle equal in size, preopercle that only borders the subopercle but does not reach the opercle; dermal skull bones strongly punctate, with externally smooth upper and lower jaw bones. Discovery of a coccolepidid at Holzmaden represents the first occurrence of the group from a Toarcian deposit, as well as the oldest record of the family in mainland Europe. Both described specimens of †T. morlok were victims of successful predation events: one individual was likely decapitated (pabulite) and the other preserved within a regurgitalite (fossilized oral ejecta). The evolution of Coccolepididae is discussed briefly in relation to a marine/freshwater origin.