Boletín de la Sociedad Geológica Mexicana Volumen 66, núm. 3, 2014, p. 471-482 http://dx.doi.org/10.18268/BSGM2014v66n3a5

Briozoarios del Orden Fenestrida, Pensilvánico de la Formación Ixtaltepec, Municipio de Nochixtlán, Oaxaca; consideraciones paleoambientales

Sergio González-Mora^*,1, Francisco Sour-Tovar¹

¹ Museo de Paleontología, Departamento de Biología Evolutiva, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México, D.F., México.

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 Abstract

Five bryozoan forms of the order Fenestrida, found in Pennsylvanian rocks of Ixtaltepec Formation, are described: Rectifenestellasp. (Fenestellidae) and Polyporella sp., Polypora sp., Penniretepora sp. 1 and Penniretepora sp. 2 (Acanthocladiidae). The presence of these genera is coherent with paleobiogeographic affinities that have been proposed in previous studies and that have reported strong similarities between Carboniferous faunas of Santiago Ixtaltepec and contemporary faunas from the Mid-Continent region of the central eastern United States. The discovery of the taxa described herein in levels API-6 and API-7, middle-upper part of Ixtaltepec Formation, establishes for the first time their presence in the Pennsylvanian of Mexico, age previously dated by the presence of several groups of brachiopods. The morphology of the bryozoans colonies described in this study indicates a paleoenvironment of deposit of periarrecifal type, with low energy, muddy bottom, well lit, with warm and shallow waters.

Keywords: bryozoans, Fenestrida, paleoenvironments, Pennsylvanian, Oaxaca, Mexico.