CARBONIFEROUS BRACHIOPODS (PRODUCTIDA AND ORTHOTETIDA) FROM SANTIAGO IXTALTEPEC, OAXACA, SOUTHERN MEXICO

Ten species of Carboniferous brachiopods of the orders Productida and Orthotetida are described. The material occurs in Santiago Ixtaltepec, considered as one of the most important regions where Paleozoic rocks of Mexico are exposed. Ozora sp., Tolmatchoffia keokuk and Marginatia sp. were found in rocks from the Santiago Formation (APS-1), meanwhile the other taxa were collected in different strata from the Ixtaltepec Formation (API-2, API-5, API-6 and API-7). The record of the genera Ozora and Matginatia and the species Tolmatchoffia keokuk corroborate the Tournaisian-Visean age for the Lower Member of the Santiago Formation. The presence of Productus concinnus at API-2 level of the Ixtaltepec Formation places it in at least Visean age. Antiquatonia sp., Orthotetes mixteca, Derbyia sp. and ?Schuchertella sp. were found in previously dated Pennsylvanian strata. The fossil associations and the lithology allowed to relate each level where brachiopods were found with an intertidal, subtidal or peri-reef paleoenvironment. The presence of typical taxa from the Tournaisian of the Mid-Continent (United States) in the Santiago Ixtaltepec region suggests that there was a marine connection that joined both areas at least since the Early Mississippian. The occurrence of Productus concinnus in the Ixtaltepec Formation (API-2) confirms that Europe and Santiago Ixtaltepec region were linked during the Middle Mississippian. Antiquatonia, Orthotetes, Derbyia and Schuchertella are considered as cosmopolite genera whose presence in localities from the Mid-Continent is very common.