The role of bryozoans in fossil reefs—an example from the Middle Devonian of the Western Sahara

Abstract

Stenolaemate bryozoans with their stable calcitic skeletons play a signiWcant role in reef building. In the Middle Devonian Sabkhat Lafayrina reef complex (Western Sahara), bryozoans are abundant and diverse. Although they do not form part of the principal framework of reefs, bryozoans are involved signiWcantly in reef growth, especially in the initial stage. In this way, bryozoans are important with respect to initiating reef growth. They contribute greatly to sediment stabilization, making it possible for principal reef builders to grow on hardened and stabilized substrates, and also play sediment-baZing and sedimentWlling roles. The aim of this study is to document the diversity of bryozoans in a Middle Devonian reef complex and to estimate their potential for initiation and contribution to reef structures.

Secular changes in colony‐forms and bryozoan carbonate sediments through geological history

“…A ‘bryozoan belt’ developed during times of low sedimentation in a shelf area receiving terrigenous mud and detrital carbonates from different source areas, the bryozoan colonies forming thickets (Brett, ). Ernst & Königshof () described a mixture of branching and fenestrate colony morphotypes in the Sabkhat Lafayrina reef complex (Givetian) of Western Sahara. While not significant as reef framework builders, these bryozoans may have had a sediment‐baffling role as well as stabilizing the sediment.…”

Roles of clone–clone interactions in building reef frameworks: principles and examples

“…40) and erect, locally fused fenestrate bafflers described by McKinney (1981). These bryozoan frame-builders occurred either alone or in conjunction with other frame-builders in Late Paleozoic reefs (Ernst and Königshof 2008). Still others were dwellers or sediment-formers, i.e., members of the Dweller Guild.…”

“…362-363, 1985, regarded the fenestellid zoaria from which the fragments were derived as ''accessory'' and their role as bafflers in reef building as similar to the associated stemmed crinoids (classic bafflers; Fagerstrom 1987, pl. 5b;Ernst and Königshof 2008).…”

“…5a, 25b, 28, 29b, 30b, 46) and fenestrate bryozoans (Ernst and Königshof 2008); all are members of the Baffler Guild. Such pores may also contain significant volumes of microbialites and cement produced by calcimicrobes (Webb 2001;Shen and Webb 2008).…”

Unusual skeletal morphology and systematic description of a new Devonian cryptostome bryozoan from the Western Sahara

“…The sedimentological units are characterised by shallowing upward cycles. Bryozoans occur preferentially in the lower part of the reef complex and have been found mainly in grainstones (Ernst and Königshof 2008). They are associated with branching tabulate corals, dendroid stromatoporoids, and brachiopod debris.…”