A paleoecological trophic network model of the Early Ordovician Lower Fezouata Shale (Morocco) fossil fauna

The fauna of the Fezouata Shale, an Early Ordovician fossil Lagerstätte from Morocco, is transitional between the Cambrian and the Great Ordovician Biodiversification Event (GOBE). We compiled a comprehensive taxa list for the Lower Fezouata Shale and developed its empirical trophic network. We compared it to four modern marine networks and a modeling by the niche model, known for accurately representing modern trophic networks. The Fezouata network, compared with modern ones, had higher proportions of top, herbivore, and basal taxa, indicating a community defined by the coexistance of top predators typical of both the Cambrian and the Ordovician and the dominance of low-trophic-level taxa such as filter-feeders, whose expansion characterized the GOBE. These diversifying taxa were also mostly generalists. The Lower Fezouata trophic network did not significantly differ from its niche model prediction, suggesting that most elements of modern trophic network structure had already appeared by the Early Ordovician.