Les tortues du Mésozoïque du Havre (France), révisions, définition de Globochelus lennieri n. g. n. sp. et nouvelles données sur Tropidemys langii, Plesiochelyidae

Abstract

The collection of Mesozoïc turtles conserved in the Museum of Le Havre is revised, being enhanced after the destruction which occurred during the World War II. The new purchases, including two new Jurassic (Lower Kimmeridgian) taxa of the family Plesiochelyidae, from the Cap de la Hève and Bléville respectively, are compared to the previously described turtle and now destroyed remains of the Le Havre area. On the one hand, Globochelus lennieri n. g., n. sp., from the basal Kimmeridgian Baylei biozone is the oldest plesiochelyid species named from the Upper Jurassic, that we dedicate to Lennier, in tribute to his works about geology and fossils from Le Havre. On the other hand, Tropidemys langii, from the Cymodoce biozone, is a form from the European Kimmeridgian whose presence in the Normandy region was doubted. The stratigraphic series of Le Havre, from Lennier and recent works, the sedimentology of the fossiliferous layers and the petrography of the calcareous matrix are examined, showing a littoral platform environment. The Le Havre fossil turtle record including destroyed species is reconsidered: notably the Lower Kimmeridgian plesiochelyid Plesiochelys dollfusii (Lennier), this species being clearly distinctive in the genus, and the early Cretaceous « Palaeochelys » novemcostatus Valenciennes, attibuted to a pre-employed genus but which is here confirmed as a Chelonioidea as, perhaps, “Pelobatochelys sp?”. The morphology of the shell of each plesiochelyid genus is compared. Some species previously attributed to Thalassemys are integrated in plesiochelyid genera.