Fenestella and other bryozoans in the Carboniferous rocks of the British Isles

Paul D Taylor (UK) Ask a geologist to name a fossil bryozoan found in the rocks of the British Isles and the most likely answer will be Fenestella. The net-like fossils of Fenestella are especially abundant in the Carboniferous Limestone (Figs 1 and 2), although the genus, as used in its broadest sense, is also present in the Silurian, Devonian and Permian deposits of Britain. Fig. 1. Colony of Fenestella (s.l.) nodulosa from the Lower Carboniferous of Calcot Quarry, Halkyn Mountain, Flintshire. Branches forming the characteristic meshwork fan outwards from the colony origin. Fig. 2. Large colony of Fenestella (s.l.) flabellata from the Carboniferous Limestone of Fife in Scotland. Fracturing of the meshwork is evident. While Fenestella dominates almost all bryozoan assemblages found in the British Carboniferous, a variety of other bryozoans are commonly found. Some Carboniferous bryozoans inhabited reefs or mounds, others were components of non-reef marine communities where they lived together with brachiopods, crinoids and corals at a time when the British Isles was situated close to the equator. All Carboniferous bryozoans constructed immobile colonies consisting of numerous individual zooids, with crowns of tentacles used to capture tiny planktonic algae floating in the water around. Our knowledge of the diversity of Carboniferous bryozoans in the British Isles has increased enormously during the last 50 years through the studies of David E Owen, Ron Tavener-Smith, Adrian J Bancroft and Patrick N Wyse Jackson. Yet, and in common with bryozoans from other geological periods, Carboniferous bryozoans are too often perceived … Read More