Paleogeographic, paleoecologic, and paleoenvironmental controls on the evolution of bottom-level communities during Cambrian times. – CambrianEco

The Neoproterozoic-Cambrian transition (about 580-520 Ma) records one of the most important events in the evolution of the Biosphere on Earth. This biotic event, also known as the Cambrian explosion , is characterized by the emergence and diversification of almost all extant metazoan phyla and numerous extinct ones. Another feature of the Cambrian explosion is the polyphyletic appearance of a number of mineralised animal skeleton types (biomineralisation event). Nevertheless, this event can also be considered as an ecological radiation. It marks a transition from microbial-dominated ecosystems to a modern biosphere ( agronomic revolution ), during which different communities succeeded: microbial communities, first metazoan mineralised-skeleton (the so-called small shelly fossils ), first archeocyathan-reefal communities and non-reefal echinoderm-sponge meadows, etc. Their related synecological interactions increased significantly, leading to niche partitioning and more complex biotic structures (trophic guilds, ecospace utilization, etc.) within a wide spectrum of ecosystems. Finally, this time span has recorded numerous paleogeographic and paleoclimatic events. The aim of the project is to better understand the spatio-temporal evolution and the differentiation processes of the benthic, marine ecosystems during the 'Cambrian explosion', by forcing the relative influence of paleogeographic, paleoecologic (autoecology and synecology), and paleoenvironmental (paleoclimatic) controls on the observed benthic replacements. To bring out these goals an original, multidisciplinary (paleontological/ paleogeographic/ sedimentological/ (bio)geochemical) methodology will be established. It will compare benthic communities from the western Gondwanan margin (modern Mediterranean area) and the South China plate. In order to allow differentiating local and global factors of establishment and differentiation of ecosystems during Early Cambrian times, two different communities developed in two different environments will be studied from each area: (i) the 'echinoderm-sponge meadows' preserved as relatively proximal, carbonate bioaccumulations and (ii) the 'arthropod communities' preserved as so called Lagerstatten (deposits with extraordinary fossil-preservation) in distal siliciclastic, muddy environment (Chengjiang , China and Villeneuve Minervois, France). The comparison of the trophic webs and identification of the different feeding strategies among communities, including major primary producers (microbial vs phytoplanktonic), represent a major innovation in study of Cambrian Explosion. It will allow, through qualitative and quantitative modern methods, to establish a possible relation between biological and ecological diversification. Moreover, the description of simultaneous evolution of palaeobiological and palaeogeochemical proxis will allow testing the correlation between biological, ecological and environmental events, and thus, to better understand the processes of appearance and differentiation of modern marine ecosystems on Earth. This project is aimed at generating a nationally and internationally acknowledge group of competitive and innovative research in the thematic of Biotic and abiotic controls of biodiversity during major Palaeozoic Earth History Events ...