Discovery of the Middle-Late Triassic elasmobranch ichthyoliths from the Guanling area,Guizhou,SW China

Abundant Middle-Late Triassic(Ladinian-Carnian)elasmobranch ichthyoliths(microscopic shark dermal denticles and teeth)from the Zhuganpo and Xiaowa Formations in the Guanling area,Guizhou Province,south-western China,are described and illustrated.The fauna includes a single tooth possibly belonging to Hybodontidae and7paragenera and paraspecies of dermal denticles,i.e.:Lobaticorona cf.floriditurris,Sacrisubcorona cf.circaba-sis,Glabrisubcoro na cf.arduidevexa,Parvicorona dacrysulca n.gen.n.sp.s.f.,Annulicorona pyramidalis n.gen.n.sp.s.f.,and new(?)paragenera A and B.This is the first time that shark dermal denticles are reported from the Metapolygnathus polygnathiformis M.nodosus conodont zones.The application of microfossils of chondrichthyes in the stratigraphic division of the Triassic and the intercontinental correlation of Triassic chondrichthyes in south-western China and those in equivalent strata in North America are also discussed.