Doctoral student (M/F) : Exceptional preservation of the brain and radiation of the jawed vertebrates

This PhD is based on the recent discovery of fossil jawed vertebrates (gnathostomes) showing ex-ceptionally 3D-preserved soft tissues in two Carboniferous (-300 million years) contemporary de-posits, one in Uruguay, the other in the USA. Exceptionally, in addition to some muscles, we found mineralized brains in two chondrichthyans (cartilaginous fishes: sharks, rays and chimaeras) in these two localities. These remarkable preservations of species that lived during an important evo-lutionary radiation step in modern gnathostomes history will be studied using non destructive im-agery technologies (XR Microtomography CT Scan and Synchrotron), which will provide new char-acters documenting the early stages of the still debated morphological evolution of the vertebrate head skeleton and central nervous system. 

This purpose will be completed by the study of the still unknown processes involved in the fossilization of a biological structure as fragile as a brain by: 

1. X-ray fluorescence elemental mapping of the fossils, 

2. a detailed characterization of the different environmental deposit conditions of uruguayan and american localities,

3. a study of the role played by the bacteria involved in the exceptional fossilization of this delicate organ. 

Therefore, thanks to these two complementary studies, this project on invaluable fossils will provide essential data for the understanding of the evolutionary history of a key organ and for the necessary condi-tions for its exceptional fossilization.

The candidate must have good knowledge of the anatomy of chondrichthyans (cartilaginous fish) and/or early osteichthyans (bony fish). Skills in segmentation and 3D modeling techniques and softwares will be highly appreciated. Skills, or at least a strong curiosity and some knowledge, on taphonomy and related methods will be required.

Speaking Spanish would be an advantage because most of the material comes from Uruguay and that several field and collection missions are planned in this country where English is not com-monly used.

General Information 

Coordinators: Gaël Clément et Alan Pradel

• Type of Contract : PhD Student contract / Thesis offer
• Contract Period : 36 months
• Start date of the thesis : 1 November 2024

More information and to apply CNRS Emploi website