Arpavoniceras buloti gen. et sp. nov.; a new lower Hauterivian heteromorphic ammonoid from southern France and its place in the evolution of Cretaceous ammonites

One specimen of an heteromorph ammonoid from the lower Hauterivian (Lower Cretaceous) of Arpavon Drôme, southern France, is referred to the new genus and species Arpavoniceras buloti. Besides the type species, Shasticrioceras anglicum Doyle, 1963, from the lower Hauterivian of Speeton (UK), is transferred to Arpavoniceras gen. nov. The Hauterivian age and general coiling of these two closely-allied taxa point to affinities with representatives of the suborder Ancyloceratina, but the ornamentation and suture line identify Arpavoniceras as a putative uncoiled offshoot of the Neocomitidae and should be referred to the suborder Ammonitina.