Morphology, type and distribution

Although stromatoporoids represented an enigma for paleontologists for decades - they were sorted into seven different animal kingdoms before being considered as a specific group of sponges, the calcispongiae, sponges whose skeletons have massively calcified -  they had already been studied in the 1950s, particularly in Belgium. Pioneering Belgian geologist Marius Lecomte devoted an entire book to them in 1952: Les stromatopores du Dévonien moyen et supérieur du bassin de Dinant. "His work was very important and remains a benchmark for researchers even today," says Da Silva. "It has not yet been updated, and since then, the stromatoporoids of the Frasnian stage in Belgium have not been studied on such a scale". However, some aspects are missing in this study; "Marius Lecomte draws up an inventory of stromatopores without connecting them to a particular area. There is therefore a link missing between stromatoporoids and the environment". It is this missing link which Da Silva wanted to find. She therefore went back to the field. She sampled four outcrops, mainly Tailfer (Namur), Prayon (Liège), the La Boverie quarry (Rochefort), and Villers-le-Gambon. A month of fieldwork and several hundreds of samples later, the researcher went to London to meet with renowned stromatoporoid specialist, Steve Kershaw from Brunel University. Basing themselves on the work of, among others, Marius Lecompte to identify the fossils, they described the fauna of stromatoporoids as it developed in the very varied environments in the Frasnian stage in Belgium - lagoon, reef, and deep zone - mapping out different species and their morphology as well as the condition in which they were preserved. "We then linked these data with the different environments," continues the young geologist, before going on to present their initial findings: "it appeared that the types of stromatoporoids which we had observed - thirteen in total - as well as the morphology of the fossils varied depending on the environment: stromatoporoids with laminar morphology were found in deep, calm zones characterized by the presence of significant fine particles (calcium, mud, and clay), while domical forms were found in shallow water, and the branching forms were present in most environments".