Carboniferous biostratigraphy of Sonora: a review
A thorough review of the available literature regarding biostratigraphic studies on the Carboniferous sedimentary rocks of Sonora, northwestern Mexico, is presented here. Most frequently reported fossils are marine invertebrates as well as protozoans and vertebrate remains. Most abundant groups are corals, both solitary and colonial, fusulinids and other foraminifera, conodonts, and brachiopods. Less commonly described groups are crinoids, algae, bryozoans, and radiolarians. This revision evidences the high paleobiodiversity and potential research interest of the Carboniferous geological record of Sonora. Although published studies including paleontological information greatly lack detailed specific taxonomic determinations or biostratigraphic analyses, the presence of all Mississippian and Pennsylvanian stages can be inferred. Regional stratigraphic gaps and hiatuses, however, are difficult to determine because of this scarcity of precise datings. Current lithostratigraphic units defined formally or informally are also reviewed.