Youngest occurrence of a plethodid fish (Teleostei: Tselfatiiformes: Plethodidae) from the Maastrichtian of North Africa

Abstract

An isolated dermobasihyal bone belonging to an indeterminate plethodid fish (Tselfatiiformes) is described from Upper Cretaceous strata of the Plateau des Phosphates of central Morocco. The morphology of the new dermobasihyal bone is highly diagnostic of the family Plethodidae and has affinities with the genera Pentanogmius, Bananogmius, and Martinichthys. Despite these close similarities, its exact generic assignment remains ambiguous. The specimen is significant as it represents the first record of Plethodidae in the Maastrichtian – thereby extending the family's stratigraphic range into the uppermost stage of the Cretaceous. Previous assumptions that plethodids went extinct during the Campanian is proven to be false, with Plethodidae now demonstrated to have survived into the late Maastrichtian, likely becoming extinct along with the non-avian dinosaurs and pterosaurs at the K-Pg Mass Extinction.