Boletín de la Sociedad Geológica Mexicana

Volumen 69, núm. 2, 2017, p. 409 ‒ 420

Reptonoditrypa cautica, briozoo incrustante de los olistolitos Cipit de la Formación San Cassiano (Triásico, Ladiniano/Carniano; NE de Italia) y sus implicaciones paleoecológicas

Francisco Sánchez-Beristain, Joachim Reitner

 

Francisco Sánchez-Beristain
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Museo de Paleontología, Facultad de Ciencias, Universidad Nacional Autónoma de México, Av. Universidad 3000, Coyoacán 04510, CDMX.

Joachim Reitner
Centro de Geociencias de la Universidad de Göttingen, Goldschmidtstraße 3, D-37077 Göttingen, Alemania.

 

Abstract

Reptonoditrypa cautica Schäfer and Fois is a bryozoan species that constituted an important part of the encrusting/binder guild of the Triassic reefs, mainly in the Ladinian and Carnian. In the Cipit boulders of the St. Cassian Formation, it is usually associated with specimens of the thalamid sponge Cryptocoelia zitteli (a member of the constructor/baffler guild), although it can also be seen forming crusts along with microbialites on top of other species of reef builders. It is worth mentioning that, although the sponge is always linked to the bryozoan, this does not apply for the opposite. It is also worth to pinpoint the absence of Reptonoditrypa cautica in other thin-section samples of reef facies from these boulders, as well as the fact that it is the only kind of microencrusting bryozoan found in about 400 thin sections.

This article explains the paleoecological role played by this species in the reef systems of the St. Cassian Formation.

Keywords: Bryozoans, encrusters, reef guilds, Triassic, St. Cassian Formation.