On the status of Kaiparaites Matsumoto, 1955 (Cretaceous; Ammonoidea: Kossmaticeratidae)

Abstract

The kossmaticeratid ammonite Kaiparaites was on its inception synonymized by its author (Matsumoto 1955) with Natalites (Collignon 1954). However, close comparison of the type species of these two genera shows them to be morphologically and stratigraphically distinct. Whereas Santonian Natalites shares the flexed constrictions of late Turonian–Coniacian Kossmaticeras, the straight constrictions of late Campanian – Maastrichtian Kaiparaites are shared with Caledonites, Gunnarites, Grossouvrites and Jacobites. Consequently, Kaiparaites is resurrected from the synonymy of Natalites and demonstrates that, under phylogenetic consideration, characters first thought to be of prime taxonomic significance actually turn out to be secondary. Since treatment of Natalites as a subgenus of Kossmaticeras emphasizes primitive characters, it is returned to generic rank, as is Santonian Karapadites although, for those who find use for subgenera, the latter can be treated as a subgenus of Natalites.