Taphonomy and systematics of decapod crustaceans from the Aptian (Lower Cretaceous) in the Oliete Sub-basin (Teruel, Spain)

Abstract

Decapod crustaceans from the Forcall Formation (Aptian, Lower Cretaceous) of the Oliete Sub-basin (Maestrazgo Basin) are recorded, specimens having been collected from the localities of Josa and Obón (Teruel) in the Aragonese branch of the Iberian Cordillera, northeast Spain. The glypheid lobster Atherfieldastacus magnus is by far the commonest species at several stratigraphical levels. Minor components of the decapod crustacean fauna include axiidean shrimps (Aptaxiopsis longimanus gen. et sp. nov., Crosniera forcallensis sp. nov., Meticonaxius gracilis sp. nov., Aptanacalliax enigma gen. et sp. nov.), a glypheidean lobster (Meyeria ornata), a hermit crab (Cretacocalcinus josaensis gen. et sp. nov.) and a brachyuran, Mithracites vectensis Gould, 1859. Meticonaxius gracilis nov. sp. represents the oldest fossil record of this genus to date. Aptanacalliax enigma gen. et sp. nov. and Crosniera forcallensis sp. nov. are considered to be the earliest occurrences of the families Anacalliacidae and Callianideidae, respectively, at this date. The specimens studied document two different modes of preservation, which also have an impact on the diversity of each assemblage. Our collections include specimens preserved within calcareous concretions and those preserved in mudstones. The assemblages studied are considered parautochthonous, i.e., were preserved within or close to their habitat and were entombed by obrution events that accumulated sediment and bioclastic material within an offshore setting.