Article: The European species of the Cretaceous ammonite Romaniceras with a revision of the genus

The genus Romaniceras Spath, 1923, is shown to be a member of the subfamily Euomphaloceratinae Cooper, 1978, derived probably from Kamerunoceras Reyment, 1954. Three subgenera are recognized: R. (Romaniceras), R. (Yubariceras) Matsumoto, Saito, and Fukada, 1957, and R. (Obiraceras) Matsumoto, 1975. The European Turonian yields three successive species: R. (R.) kallesi (Zazvorka), of which R. hispanicum Wiedmann is a synonym; R. (Y.) ornatissimum (Stoliczka), of which R. (Y.) deverioides (de Grossouvre) and .R. (Y.) yubarense Matsumoto, Saito, and Fukada are the most important synonyms; and R. (R.) deverianum (d'Orbigny) of which R. (R.) uchauxiense Collignon, R. (R.) medlicottianum (Stoliczka), R. (R.) pseudo-deverianum (Jimbo), and R. (R.) yezoense Matsumoto are the most important synonyms.Dimorphism is tentatively recognized in R. (Y.) ornatissimum, and it is shown that there is a high degree of intraspecific and ontogenetic variability in both R. (Y.) ornatissimum and R.(R.) deverianum, comparable to that seen in other acanthocerataceans.