New identifications of radiolaria and conodonts allow clarifying the biostratigraphy of the Pennsylvanian and Permian deposits in San Salvador Patlanoaya (Puebla State, Mexico). The radiolaria are sometimes relatively common in the series, but weakly diversified and endemic. Among the conodonts, Streptognathodus bellus is characteristic of the Late ‘Virgilian’ sensu Baars, probably coeval with the Early Wolfcampian sensu Thompson or Wilde, the Bursumian of Ross & Ross or the Orenburgian–Asselian stage or substage of Russia (sensu Davydov). San Salvador Patlanoaya is a key-section for the Pennsylvanian–Permian boundary in Mexico.
Pennsylvanian, Permian, biostratigraphy, conodont, radiolaria, Mexico