The early Palaeozoic biodiversification is the most significant radiation of marine ecosystems of Earth’s History. In a simplified way, it started with the appearance of invertebrate organisms near the Precambrian-Cambrian boundary and was followed by a significant diversification during the Great Ordovician Biodiversification Event. The apparently sudden appearance of life during the earliest Cambrian (Cambrian ‘Explosion’) has been considered by many as corresponding to an ‘explosive’ process that took place during a very short time-interval. Scenarios proposed in the last decades in high-impact publications (e.g. Fox 2016) regularly promote the exciting story of an ‘evolutionary burst’ 540 million years ago. As a result, the wider public considers today that life appeared suddenly on Earth during a short event. Similarly, some authors propose a short spectacular global event triggering a massive biodiversification during the early Middle Ordovician some 470 million years ago, related to meteorite impacts and/or radical changes in ocean circulation and climate (e.g. Trotter et al. 2008; Rasmussen et al. 2019). However, in recent years, it became obvious that both ‘events’, the Cambrian ‘explosion’ and the Ordovician biodiversification ‘event,’ have been more intensively studied in a few locations, creating a gap of data, and thus a bias, in the biodiversity datasets (Harper et al. 2020; Servais et al. 2021; Raja et al. 2022). Furthermore, recent investigations continuously document that the exceptional fossils of the Cambrian ‘explosion’ are still present in the fossil record much later, for example in the Lower Ordovician of Morocco (Van Roy et al. 2010). A number of publications, related to the Fezouata Biota of Morocco, show that the Cambrian ‘explosion’ and the Ordovician ‘event’ are indeed actually closely linked (Lefebvre et al. 2016) and difficult to discern.

L'Équipe Projet

Membres du Laboratoire

Gregory Beaugrand

Directeur de Recherche (CNRS)