Taxonomic and paleobiogeographic review of the Guadalupian ammonoids reported by González-Arreola et al. (1994) from the Olinalá Formation, Guerrero state, Mexico

• Published in: Journal of South American earth sciences 2024-10, Vol.146, p.105072, Article 105072
• Main Authors: Alanis-Pavón, Alberto, Moreno-Bedmar, Josep Anton, Torres-Martínez, Miguel A.
• Format: Article
• Language: English
• Subjects: Ammonoid; Guadalupian; Guerrero state; Mexico; Olinalá Formation; Permian
• ISSN: 0895-9811
• DOI: 10.1016/j.jsames.2024.105072

A review of twenty-five ammonoid specimens of the Guadalupian age from the Olinalá Formation, Guerrero state, as recorded by González-Arreola et al. (1994) is presented as part of a study of middle Permian ammonoid faunas from Mexico. The present update includes new images of González-Arreola's ammonoids. Six taxa have been identified to species level and one species in open nomenclature. Three taxa recognized by González-Arreola et al. have been revised and reassigned to other genera, two species-level identifications have been changed, and a species previously not reported is for the first time described from the original designation. The ammonoid faunal composition suggests that the base to the middle part of the Olinalá Formation is correlated to the Wordian (middle Guadalupian). Reference to published paleobiogeographic data has suggested that the present ammonoid specimens be assigned to the American Realm and indicates a clear affinity with contemporaneous ammonoid assemblages from the Paleothetys Realm. •25 ammonoid specimens from the Olinalá Formation of Guerrero, Mexico, are reviewed and described for first time.•The ammonoid assemblages contain Permian taxa, particularly from the Guadalupian (Wordian-Capitanian).•The taxa allowed the accurate dating of the lithostratigraphic unit.•Ammonoid assemblages resemble faunas from other geographical regions, such as northern Mexico, United States, and Canada.