Postdoctoral position: "Tracing the origin of vertebrate’s major ecological transitions with lithium isotopes" - LGL-TPE (UMR5276)

Research project

The aim of the postoc project is to document the potential of Lithium isotopes to identify living water environments of extant and extinct vertebrates, and to understand the origin of the factors that control Li isotope fractionation and Li transfers within different past and present vertebrates’ environments.

Using a representative number of analyses, the candidate will investigate whether this proxy based on Li isotopes can be applied to all vertebrate groups such as bony fishes, sharks, mammals, reptiles and amphibians. Bone and tooth samples of extant species living in contrasted environments (marine, brackish, fresh) are available for analysis. The ultimate goal is to establish a precise proxy to the vertebrate living environment based on the combined use of Li, O and S stable isotopes that can be applied to the fossil record.

The established proxy will then be tested on Miocene vertebrates’ bones and teeth from the Falun deposits, where marine and continental species are found in association. These samples are already on our procession and their δ18O values have been published.

Depending on the results, the candidate will then focus on one of the main questions of vertebrates’ ecological transition: the Devonian terrestrialization of tetrapods. He/she will use bones samples from Devonian tetrapods, already in our possession and previously analysed for their δ18O and δ34S values that revealed the freshwater or seawater influence on the living environment of the Devonian tetrapod species. Li isotopes will allow to refine previous conclusions by specifying the species that live in transitional environments.