| The Cretaceous corals (Anthozoa, Scleractinia) of the Huetamo region of southwestern Mexico, an area in the tectonically problematic Guerrero terrane, are investigated for the first time. This study provides a detailed, modern taxonomic foundation for future work on Mexican Cretaceous corals. Thirty-nine species are described and illustrated: 20 from the lower Aptian Cumburindio Formation, one from lower Aptian strata of the San Lucas Formation, and 18 from the upper Albian - lower Cenomanian upper member of the Mal Paso Formation. The coral faunas from these formations are entirely different from each other. Of the 21 species from the lower Aptian, three are described as new: Saltocyathus cumburindioensis, Actinaraea michoacanensis, and Thamnarea hornosensis. About 50 percent of the lower Aptian coral species have been reported previously from pre-Albian strata in the European region. This faunal similarity was the strongest geographic affinity recognized in this study. Of the 18 coral species from the upper Albian - lower Cenomanian, 12 are described as new; one genus, Blastozopsammia, also is described as new. The 12 newly described coral species from the upper Albian - lower Cenomanian are: Actinastrea chumbitaroensis; Preverastraea coatlicuae; Preverastraea tocae; Latiphyllia mexicana; Thecosmilia guerreroensis; Mycetophyllopsis azteca; Orbignygyra? incognita; Blastozopsammia guerreroterion; Thalamocaeniopsis mexicanensis; Thamnasteria tonantzinae; Paracycloseris effrenatus ; and Ovalastrea malpaso. Analogies with living corals indicate that most of the fossil corals were reef-building species.; Associations of scleractinian corals and rudist bivalves were observed at three localities, two in the Cumburindio Formation and one in the Mal Paso Formation. The two occurrences in the Cumburindio Formation are: an association of a large species of ramose, microsolenid coral, Thamnarea hornosensis , preserved in situ along with valves of the rudists Praecaprina and Caprina at the exposures in the Arroyo Los Hornos; and a diverse assemblage of reef corals that conformably overlies a bed primarily composed of valves of the rudist Amphitriscoelus near the top of the section at the Loma de San Juan, Turitzio. The cora-rudist association in the Mal Paso Formation concerns a diverse assemblage of reef corals and the rudists Radiolites and Mexicaprina . None of these specific kinds of faunal associations between corals and rudists has been reported previously. |
