Towards a standard ammonite zonation for the Aptian (Lower Cretaceous) of northern Mexico

  • Ricardo Barragán-Manzo Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México, D. F., Mexico.
  • Ana Laura Méndez-Franco Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México, D. F., Mexico.
Keywords: biostratigraphy, ammonites, Aptian, Mexico.

Abstract

Detailed data on twenty-seven species of ammonites identified in three stratigraphic sections of northern Mexico, allow further refinement of the Aptian ammonite biozonations of previous authors. Four formal ammonite biozones are proposed. Dufrenoyia justinae Taxon-Range-Zone for the uppermost part of the lower Aptian (Bedoulian), Epicheloniceras cf. subnodosocostatum/Acanthohoplites acutecosta Interval Zone representative of the middle Aptian (Gargasian), and Acanthohoplites aschiltaensis and Hypacanthoplites cf. leanzae Taxon-Range-Zones, spanning the upper Aptian (Clansayesian). The ammonite zonation proposed represents the advancements on the development of a standard scheme towards a reliable correlation with the biozonal scheme of England and the ammonite zonal standard of the Mediterranean area.

Published
2018-05-07
Section
SPECIAL SECTION, Mesozoic Invertebrate Paleontologyc