Correlation of the late Lasnamägian Stage (Middle Ordovician) with the graptolite succession

Shaly strata of the Didymogruptus murchisoni Zone at Killeröd, Skane, southern Sweden, have yielded elements of the conodont species Pygodus serrus (Hadding) and Eoplacognathus reclinatus (FBhraeus) which are characteristic of the Folkeslunda Limestone of late Lasnamägian age. These species provide the first conclusive evidence that at least part of the late Lasnamägian is coeval with the Didymogruptus murchisoni graptolite Zone. The presence of Pygodus anserinus Lamont and Lindström and Prioniodus prevariabilis Fahraeus through-out the 'Bronni Beds" at Killeröd proves that this unit is older than has been believed previously and is equivalent to part of the Gfyptogruptus teretiusculus Zone rather than to the Nemagraptus gracilis Zone. Other evidence for the correlation between the North Atlantic graptolite and conodont zonal successions is also reviewed.