Evolutionary history of Palaeozoic Labechiida (Stromatoporoidea)

The Labechiida is the most primitive, conservative order of Palaeozoic stromatoporoids, containing four main families. Most of the 30 known genera have a comparatively simple, nonporous, aspiculate, calcareous skeleton of latilaminae, cysts and pillars with cone-in-cone structure and/or denticles. Mamelons are common but astrorhizae are rare. Their 110 my history commenced in the early Middle Ordovician with rapid diversification, to a peak of some 20 genera by the end of the Middle Ordovician. Then they gradually declined and remained subordinate to more advanced stromatoporoids. They were significant frame builders in Ordovician reefs, but had an insignificant role in the late Silurian to Middle Devonian. At the end of the Frasnian, the stromatoporoid-dominated, reef community collapsed, and many of the more advanced stromatoporoids disappeared. A resurgence of the labechiids followed in the Famennian, with 14 genera and again provided frame-building contributions to the associated reefs.