Adaptive strategies in the evolution of encrusting tentaculitoid tubeworms

The encrusting tentaculitoid tubeworms (Middle Ordovician to Middle Jurassic) have their acme of diversity in the Middle Paleozoic and they form a part of the Paleozoic evolutionary fauna. Most of the morphological and ecological innovations of encrusting tentaculitoid tubeworms appeared during the initial phase of their evolution in the Ordovician and Silurian, and no innovations appeared after the Devonian. The evolutionarily most successful (long lasting) were general hard substrate encrusters, and the most successful morphologies supported this life mode. The morphologies that lasted the longest appeared in the beginning of tentaculitoid tubeworm evolution (during the Ordovician). The ecological innovations with the shortest durations were associated with highly dependent distorting symbiotic and endosymbiotic life modes. Predation pressure may have led to evolution of defensive morphologies (e.g. spines and thick vesicular walls) and endosymbiotic life mode in cornulitids, trypanoporids, Anticalyptraea and Streptindytes.