The N’kob Biota (Middle Ordovician, Morocco): An exceptional window into high-latitude marine ecosystems

Abstract

The Great Ordovician Biodiversification Event represents one of the most important diversifications of marine life. Konservat-Lagerstätten (localities that yield exceptionally preserved fossils of lightly and non-biomineralized organisms) present a unique opportunity to understand the full scope of such an event, yet they are somewhat limited in the Ordovician compared to the Cambrian. We report the N’kob Biota, a new Middle Ordovician Konservat-Lagerstätte from Morocco. The assemblage contains articulated echinoderms, trilobites, brachiopods, hyoliths, mollusks, cnidarians, graptolites, and lightly biomineralized organisms, including paleoscolecids, marrellomorphs, and other weakly sclerotised arthropods. This site fills a critical temporal gap in exceptionally preserved biotas between the Early Ordovician Fezouata Biota and the Late Ordovician Tafilalt Biota. The N’kob Biota retains few Cambrian-type holdovers while showcasing the rapid diversification of typical Ordovician suspension feeders. This suggests that the replacement of the Cambrian-type fauna by the Paleozoic-type fauna was more gradual in high-latitude Gondwana than previously thought.