Lower Cretaceous ammonites from the Neuquén Basin, Argentina: the Hauterivian neocomitid genusHoplitocrioceras (Giovine, 1950)

Hoplitocrioceras is a poorly-known ammonite genus of late Early Hauterivian age that may be endemic to the Neuquén Basin Argentina where it occurs at a clearly defined horizon in the Agrio Formation. It is an unusual genus with uncoiling (crioceratitid) whorls that remain linked by a thick dorsal shell that drapes over the tips of sharp upwardly-pointing ventro-lateral spines. It has been interpreted as either a necomitis or a crioceratitid but is here regarded as one of the last members of the Family Neocomitidae. One new species is proposed: H. giovinei. Fil: Aguirre-Urreta, Maria Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Rawson, Peter F.. Colegio Universitario de Londres; Reino Unido