Gross structure and microstructure of Stromatoporella granulata (Nicholson, 1873) and their consequences on the definition of some Devonian stromatoporoid genera

In the abundant material of the species described in this paper great variation occurs in the form of the coenosteum, the structure of laminae and pillars and the microstructure. The shape of the coenosteum is dependent on environmental factors such as the form of the substrate, wave action, currents and sedimentation. These factors influence the ratio between the vertical and horizontal growth rates and the formation of mamelons, astrorhizae and latilaminae. The same ecological conditions also greatly influence the superposition of pillars and the formation of repair tissue and cyst plates. The number of laminae per mm is rather constant, it only varies between certain limits. Ring pillars are not considered as a generic character for they are associated with very different types of microstructures. Microstructures can be changed very strongly by alterations before, during and after sedimentation. Laminae are originally composed of two or more compact layers with a clear layer or vacuoles between them. They can become transversely fibrous, flocculent and pseudocellular by recrystallization. For these reasons great variations in the fossil material occur and are the cause that many new genera and species were created adding to the great confusion in the classification of stromatoporoids. The following genera are probably synonyms: Stromatoporella, Clathrocoilona, Stictostroma, Trupetostroma and Taleastroma. Many species have also erroneously been described as helonging to other genera, principally Stromatopora, Syringostroma and Parallelopora.