Shallow Origins? – Evolution of Animal Skeletons in the Earliest Cambrian

Summary

One of the defining events in the evolutionary history of life on Earth was the radiation of animals and evolution of animal skeletons during the late Ediacaran and early Cambrian (the Cambrian Explosion; 550-520 Ma). This project will test hypotheses regarding the evolutionary pressures behind the evolution of skeletons, specifically the hypothesis that shells first evolved in shallow water environments as protection against desiccation and UV-light.

During the project, sections in Mongolia, Newfoundland and China with the oldest known fossil record of shell bearing animals will be targeted. Rock samples will be collected to retrieve Small Shelly Fossils, the earliest known animal skeletons. Each fossil horizon will be dated using stable C-isotope stratigraphy and sedimentary environments studied. Connections between fossil content and sedimentary environment will be analyzed to test the link between the environment and the evolution of shells.

For the first time, we will be able to differentiate between different factors driving the evolution of shells. As a result, a better resolution of ecological complexity and community structure in the Early Cambrian marine faunas will provide the backdrop for the evolutionary changes that led to the establishment of phyla and eventually to the emergence of modern ecosystems. In this way the project will provide new insights to help elucidate both the evolutionary and ecological processes underlying the Cambrian Explosion.

This research is funded by the Swedish Research Council (VR)

Project Participants at the Museum

Timothy Topper (researcher)