Systematics and biostratigraphy of Santonian-Lower Campanian Scaphitidae (Ammonoidea, Ancyloceratacea) from Antarctica

OLIVERO, E. B.; RAFFI, M.E.

Puerto Madryn

Congreso; RCAPA 2018; 2018

APA

Lack of recognition of sexual dimorphism in scaphitid ammonites was always a source of great taxonomic confusion, particularly in theOttoscaphitinae where the macroconchs of Yezoites Yabe are quite similar to the typical Scaphitinae genus Hoploscaphites Nowak. InAntarctica, the Santonian-early Campanian record of Hoploscaphites is a major, not resolved problem because the genus is restrictedworldwide to the Late Campanian-Maastrichtian. Here, we demonstrated that all previous mentions of Hoploscaphites in Antarctica are in errorand that they all consist of macroconchs of at least four species of Yezoites. Antarctic scaphitids are abundant in the Alpha Member, Santa MartaFormation, with more than 100 specimens of tiny Yezoites recovered from Santonian-early Campanian strata. The record includes insuccession: a) macroconchs and microconchs of at least two species of Yezoites, Santonian. One species, previously classified as Yezoites sp.1and Hoploscaphites? sp. 1, is quite similar and probably co-specific with Yezoites australis Kennedy and Klinger, from South Africa, theother, Yezoites sp. 2, is probably a new species; and b), two additional species of Yezoites previously referred to Yezoites sp. 3,Yezoites sp. 4and Hoploscaphites? sp. 2., both including micro- and macroconchs, Santonian-early Campanian. On the basis of similar stratigraphic distributionand shell features, it is concluded that previous records of Santonian-early Campanian Hoploscaphites in Antarctica are in error and that the materialis best classified as the macroconch of different Yezoites species.