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This paper describes a sclerobiont association from the Paso Hondo Formation (Roadian, middle Permian), Chiapas,Mexico. Different marine invertebrates such as hederelloids, microconchids, bryozoans, and crinoids (represented byholdfasts) encrusted brachiopod shells belonging to Athyridida and Rhynchonellida. This association is similar to thoserecorded in different Devonian localities, especially by the co-occurrence of microconchids, hederelloids, and bryozoans.Paleoecological analysis revealed that bryozoans were the most abundant sclerobionts, whereas crinoid holdfasts wereuncommon. Likewise, hederelloids and microconchids often settled on hosts previously colonized by bryozoans. Mostmicroconchids encrusted rhynchonellid shells. A positive correlation between the size of the hosts and abundance/diversityof sclerobionts was recorded. The distribution analysis suggests that sclerobiont colonization could have been influencedeither by inhalant currents of brachiopods, time of exposure, position of hosts, or by combination of all these factors.Moreover, most of commissures and foramens of brachiopods were not covered by epibionts, suggesting that there was alive interaction. Thus, studied brachiopods were likely encrusted syn vivo, and the interaction between sclerobionts andtheir brachiopod hosts was likely commensal since there is no damage to the brachiopod valves in the form of malformationsor borings. On the contrary, the epibiont cover might have served as a natural shield against predators and parasites.The Roadian age of the association is based on the stratigraphic distribution of host brachiopods. The studied associationinhabited open waters on a homoclinal carbonate ramp in the Chicomuselo region. Although encrusted brachiopods belongto the biotic Grandian Province, similar sclerobiont communities have not been previously recorded from the Permianof North America or beyond. The described community represents the youngest record of co-occurring microconchids,hederelloids, and bryozoans, as all previously known similar communities originate from the Late Devonian.

Key words: Brachiopoda, Bryozoa, Hederelloidea, Microconchida, Permian, Roadian, Mexico, Chiapas.

Miguel A. Torres-Martínez [miguelatm@geologia.unam.mx], Departamento de Paleontología, Instituto de Geología,Circuito de la Investigación Científica, Colonia Universidad Nacional Autónoma de México, Avenida Universidad3000, Alcaldía Coyoacán, 04510, Mexico City, Mexico.Olev Vinn [olev.vinn@ut.ee], Department of Geology, University of Tartu, Ravila 14A, 50411, Tartu, Estonia.Lourdes Martín-Aguilar [lourdm01@ucm.es], Máster Universitario en Paleontología Avanzada. Departamento de Paleontología,Facultad de Ciencias Geológicas, Universidad Complutense de Madrid, campus Moncloa, Calle JoséAntonio Novais, 12, 28040, Madrid, Spain.

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