ABSTRACT
Eight species of bryozoans are described from Upper Carboniferous outcrops of the Ixtaltepec Formation, Nochixtlán Municipality, Oaxaca, Mexico: Rhabdomeson sp., Rhombopora sp. (Order Cryptostomata), Fenestella s.l. sp., Spinofenestella sp., Ptylopora sp. 1, Ptylopora sp. 2, Acanthocladia sp. and Septopora sp. (Order Fenestrata). The genera listed here are in addition to five more that have been previously described for this formation. All these specimens are preserved as molds in shale and were found in Pennsylvanian (Bashkirian-Moscovian) strata. The referred taxa support the similarity between the studied fauna and coeval ones from the Mid-Continent Province of the United States and support the hypothesis of the existence of an epicontinental sea that extended from the central-eastern of North America to southeastern Mexico. The occurrence of representatives of the genus Ptylopora in levels API-6 and API-7 of the Ixtaltepec Formation indicates a protected shallow reef environment with a muddy bottom.
