First decapod crustaceans in a L ate D evonian continental ecosystem

Abstract The origin and early diversification of decapod crustaceans and their expansion from marine to continental environments are key events in arthropod evolution. Rare fossil decapods are known from the Palaeozoic, and the earliest eumalacostracans with undoubted decapod affinities are the L ate D evonian P alaeopalaemon and A ciculopoda , found in offshore marine deposits. Here, we describe a new species of the shrimp T ealliocaris found in floodplain and temporary pond deposits from the F amennian ( L ate D evonian) of B elgium, together with a rare P alaeozoic assemblage of other crustaceans (conchostracans, notostracans and anostracans) and chelicerates (eurypterids). T ealliocaris walloniensis  sp. nov. documents the earliest occurrence of continental decapod crustaceans and indicates that decapods have been part of continental ecosystems at least since the L ate D evonian.