The applications of stromatoporoid palaeobiology in palaeoenvironmental analysis

Stromatoporoids are epibenthic calcified sponges in many Phanerozoic (especially Palaeozoic) reef, and reef-related environments, and may be used as tools for all scales of palaeoenvironmental analysis. Palaeozoic stromatoporoid classification uses the calcified skeleton, and although higher level taxa may be convergent, genera and species are normally readily identifiable and have palaeobiological utility. A hierarchical growth-form classification of Stromatoporoids comprises: Level 1 (outline forms: laminar, tabular, domical, columnar, bulbous, defined with ratio limits; and dendroid, expanding conical, digitate and irregular); Level 2 (ornament, as papillae, mamelons and protuberants, give an increasing degree of disruption of the outline); and Level 3 (growth patterns of smooth and ragged margins, enveloping and non-enveloping laminations, coalescence and anastomosing). Inappropriate growth form terms in current use are rejected, especially massive and encrusting. Stromatoporoid palaeobiology applied at local scale aids determination of relative degree of contemporaneous turbulence and sedimentation; community scale study of Stromatoporoids promotes comparisons between palaeoenvironments in reef and reef-related facies. Palaeozoic Stromatoporoids may aid regional and even global event recognition, including changes in ocean states. Major gaps in knowledge are growth rates, and whether Stromatoporoids were photosensitive and/or photosymbiotic.