Exceptional preservation of comma shrimp from a mid-Cretaceous Lagerstätte of Colombia, and the origins of crown Cumacea

Mesozoic rocks with exceptional preservation of marine arthropods are known worldwide but largely restricted to high latitudes. The scarcity of assemblages with exceptional preservation in low latitudes greatly limits our understanding of the origins of several modern groups and the evolution of tropical biotas through time. Here we report the oldest Cumacea, or “comma” shrimp (Arthropoda: Eumalacostraca: Peracarida) with modern affinities, from a new mid-Cretaceous (95–90 Mya) Lagerstätte in tropical South America. Cumaceans have one of the poorest fossil records among marine arthropods, despite today being abundant and speciose benthic organisms associated with fine-grained sediments with high fossilization potential. Eobodotria muisca gen. et sp. nov., found in mass-accumulation surfaces, preserves with stunning detail the gut, mouth parts, legs, pleopods, uropods bearing setae, antennal flagella, and even small eyes bearing ommatidia. These features, rarely preserved in fossil crust...