ANR ECO-BOOST

Abstract:

The biodiversification of the Lower Paleozoic is the most important radiation of marine ecosystems in Earth’s history. Two major increases in diversity are traditionally identified at the base of Cambrian Series 2 and during the Middle Ordovician. However, in recent years, it has become clear that these two ‘events’, the Cambrian ‘explosion’ and the great Ordovician biodiversification, have been studied with very unequal intensities from one region to another, resulting in strong sampling biases in biodiversity databases. Moreover, recent work has documented that exceptional fossils typical of the Cambrian ‘explosion’ were still present in the Ordovician. We hypothesize here that the Cambrian ‘explosion’ and Ordovician diversification do not represent two sudden, global and distinct increases in marine biodiversity. Our main objective is to demonstrate that these two “events” are part of long and complex spatio–temporal evolutionary processes that began at the end of the Precambrian and continued throughout most of the Lower Paleozoic. Biodiversity data will be plotted on new paleogeographic reconstructions, to produce diversity curves, but also to understand the spatial distribution of individual fossil groups. This will enable us to obtain, for the first time, spatial and temporal views illustrating biodiversity changes in early marine ecosystems, including the identification and location of diversity “hotspots”. It will also enable us to determine when the latitudinal diversity gradient (LDG) was established and how it evolves over time. Our project thus proposes to combine empirical and modeling approaches, with new tools that have never been applied to Lower Paleozoic marine ecosystems.

List of LGL-TPE participants:

• Bertrand LEFEBVRE
• Pauline GUENSER
• Vincent PERRIER