Gasterópodos y bivalvos cisuralianos (Pérmico inferior) de Otlamalacatla, Hidalgo, México

Abstract

New fauna of gastropods and bivalves colleted in outcrops of Tuzancoa Formation, near Otlamalacatla town, northeast of Hidalgo state, are described. The specimens are preserved like imperfect moulds with some deformation that limit the precise taxonomic determination. However, it is possible to report the presence of five species of gastropods from the families Bellerophontidae, Omphalotrochidae, Eotomariidae, Naticopsidae and Soleniscidae, and 20 species of pelecypods from the families Nuculidae, Mytilidae, Myalinidae, Pterineidae, Bakevellidae, Euchondriidae, Aviculopectinidae, Deltopectinidae, Chaenocardiidae, Streblochondriidae, Heteropectinidae, Acanthopectinidae, Limidae, Schizodidae, Trigoniidae, Astartidae, Sanguinolitidae and Solenomorphidae; most of these species are reported for the first time in Mexico. The principal affinities of this fauna are found in West Texas and belong to earlier Permian (Cisuralian) of Grandian province.