Cretaceous Corals from the Huetamo Region, Michoacán and Guerrero, Southwestern Mexico

Abstract

For the first time, the Cretaceous corals of the Huetamo region in southeastern Mexico, originating from the Guerrero terrain—a tectonically problematic area—are investigated. This study provides a foundation for future research on Cretaceous corals in Mexico. A total of 39 species are described and illustrated: 20 belong to the lower Aptian Cumburindio Formation, one comes from lower Aptian strata of the San Lucas Formation, and 18 are from the upper Albian–lower Cenomanian of the upper member of the Mal Paso Formation.

At the species level, the coral faunas of these formations are entirely distinct from one another. Of the 21 lower Aptian species, three are newly described: Saltocyathus cumburindioensis n. sp., Actinaraea michoacanensis n. sp., and Thamnarea hornosensis n. sp. Approximately 50% of the lower Aptian coral species have been reported from pre-Albian strata in the European region. This faunal similarity represents the strongest geographic affinity identified in this study.

Among the 18 upper Albian–lower Cenomanian coral species, 11 are newly described, while one of these species was recently designated as the type species of a new genus: Blastozopsammia guerreroterion Filkorn and Pantoja-Alor, 2004. The 11 newly described upper Albian–lower Cenomanian coral species are: Actinastrea chumbitaroensis n. sp., Preverastraea coatlicuae n. sp., Preverastraea tocae n. sp., Latiphyllia mexicana n. sp., Thecosmilia guerreroensis n. sp., Mycetophyllopsis azteca n. sp., Orbignygyra? incognita n. sp., Thalamocaeniopsis mexicanensis n. sp., Thamnasteria tonantzinae n. sp., Paracycloseris effrenatus n. sp., and Ovalastrea malpaso n. sp.

Comparisons with extant corals indicate that most of the Cretaceous coral species from the formations of southwestern Mexico were hermatypic, reef-building, and zooxanthellate-associated species.