Early Middle Devonian trilobites and events in the Nismes – Vireux-Molhain area, southern border of the Dinant Synclinorium (Belgium, northern France)

Well-preserved trilobite specimens are recorded from Eifelian strata between the villages of Nismes (southern Belgium) and Vireux-Molhain (northern France). In the area of study the lower Eifelian Vieux Moulin Member of the Jemelle Formation crops out. The diversified trilobite associations of this unit occur in dark shales and siltstones during a deepening phase and replace the comparatively poorly diversified trilobite fauna of the underlying Eau Noire Formation. This overturn of the local trilobite fauna might, in part, be considered a regional expression of the globally recognised Choteč Event. A marked influx of exotic trilobites in the Vieux Moulin Member is provisionally referred to the local Vieux Moulin Event. Trilobite diversity peaked in the middle Eifelian part (Chavées Member) of the Jemelle Formation before drastically dropping in the upper part of this formation. The manifestations in the Ardennes of the eastern North American Bakoven and Stony Hollow Events can neither be confirmed nor rejected based on the currently available data. New taxa from the early Eifelian part of the Jemelle Formation in the area of study are Asteropyge boeckae sp. nov., Asteropyge eonia sp. nov., Asteropyge filoxenia sp. nov., Cyphaspis insolata sp. nov., Cyphaspis iuxta sp. nov., Diademaproetus pertinax sp. nov., Geesops icovellaunae sp. nov., Gerastos kesselaeri sp. nov., Kettneraspis eftychia sp. nov., Pedinopariops ceuthonymus sp. nov., Pedinopariops richterianus geminus ssp. nov., Scabriscutellum archinalae sp. nov., Septimopeltis akatastasia sp. nov. and Tropidocoryphe insciens sp. nov. Our material includes exceptionally rare, well-preserved specimens from the famous “Mur des douaniers” locality near Vireux-Molhain. Additionally, Astycoryphe rugocauda sp. nov. is described from the lower Eifelian Couvin Formation (southern Belgium) and Gerastos silvicultrix sp. nov. from the uppermost Emsian Heisdorf Formation (German Eifel).