Caenogastropods and heterobranch gastropods from the Hettangian deposits of Luxembourg: palaeobiogeography and Early Jurassic faunal recovery in the western Tethys

We describe the Hettangian Caenogastropoda and Heterobranchia of the Luxembourg Sandstone Formation, a wedge of clastic sediments deposited along the eastern margin of Paris Basin during the Early Jurassic. Five new genera and 11 new species are erected: Bourguetia bipartita sp. nov., Globularia delsatei sp. nov., Oonia feidtorum sp. nov., Oonia haasi sp. nov., Jurazyga gen. nov., Microschiza pauciornata sp. nov., Angulariopsis gen. nov., Tangarilda darestei sp. nov., Brouchilda laevigata gen. et sp. nov., Brouchilda mulleri gen. et sp. nov., Turritelloidea? bockfielsensis sp. nov., Gruendelifusus melusinae gen. et sp. nov. and Kaimella tenuilineata gen. et sp. nov. Including the Patellogastropoda, Neritimorpha and Vetigastropoda recognized in a previous study, the fauna shows an overall high taxonomic diversity represented by 55 species belonging to 23 families. Multivariate and network analyses and parsimony analysis of endemicity were done to assess the palaeobiogeographic changes of the western Tethyan gastropod faunas during the Early Jurassic recovery. The results highlight the differentiation between the faunas of the European shelf and those of the intra-Tethyan carbonate platforms during the Hettangian to early Sinemurian interval, and the subsequent advent of a third faunal stock in the areas of pelagic deposition derived from the fragmentation and drowning of the carbonate platforms. Early in the Hettangian, areas of endemism with diversified faunas developed, which attests to a fast recovery after the Late Triassic biotic decline. Relationships between the degree of endemism and species richness within the main western Tethyan regions and within the major gastropod groups are discussed.