Plesiochelyidae are a major component of Late Jurassic shallow marine environ-ments throughout Europe. However, the taxonomy of plesiochelyid turtles is ratherconfused. Over the years, many taxa have been synonymized withPlesiochelysetalloni, one of the first described species. However, the holotype ofP. etalloni(andonly specimen known from Lect, the type locality) was lost for more than 150 years.This specimen has been recently rediscovered in the collections of the Muséed'archéologie du Jura in Lons-le-Saunier, France. For the first time since its origi-nal description in 1857, the holotype ofP. etalloniis redescribed and compared torelevant material. The taxonomic status of this taxon is revised accordingly. Based onthe morphology of the newly rediscovered holotype and on a reassessment of speci-mens from Solothurn (Switzerland), the speciesP. solodurensis,P. sanctaeverenaeandP. langiiare synonymized withP. etalloni. Known skull-shell associations forP. etal-loniare re-evaluated in light of the new morphological information available sincethe rediscovery of this holotype specimen. Finally, we confirm thatPlesiochelysisrepresented by a single species in the Late Jurassic of the Jura Mountains.