PriscosirenPriscosiren is an extinct genus of sirenian mammal which existed in the west Atlantic and Puerto Rico during the late Oligocene.DistributionThe type locality is the San Sebastián Limestone of Puerto Rico, with a record also known from the Chandler [Bridge Formation] of South Carolina, USA.DescriptionPriscosiren was diagnosed from other "halitheriine" dugongids by Velez-Juarbe and Domning.PhylogenyPriscosiren is recovered by Velez-Juarbe and Domning as sister to the Metaxytherium + Hydrodamalinae and Dugonginae clades.