Systema Porifera pp 52-68
Non-Lithistid Fossil Demospongiae — Origins of their Palaeobiodiversity and Highlights in History of Preservation
Available evidence suggests that the first demosponges occur in the Late Proterozoic, with forms characterized by bundles of long monaxonic spicules. In the Middle Devonian the first modern forms of Dendroceratida, ‘axinellids’ (mostly halichondrids), and first haplosclerids appeared. An important boundary for the demosponges is the Late Devonian extinction event, which caused a complete overhaul of demosponge communities. The Late Permian and the Triassic, especially the Late Triassic, are the main eras for coralline demosponge radiation and dominance, in which some modern taxa occur for the first time (Ceratoporella, Astrosclera, Vaceletia). In the Late Jurassic the freshwater environments were occupied by certain (marine) demosponges, mostly Haplosclerida. The importance of coralline demosponges as primary reef-builders decreases up to the Late Cretaceous.
KeywordsPorifera Demospongiae fossil taxa coralline demosponges
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