Exceptional preservation of the brain and radiation of the jawed vertebrates

Session AAP :

AAP 2024-4

Scientific responsibility :

  • Gaël Clément
  • Alan Pradel
  • Karim Benzerara
  • Mathieu Thoury
  • Pierre Guériau

Partnership :

Funding :


Project ID : IDF-DIM-PAMIR-2024-4-017

Summary :

This PhD stems from the recent discovery of jawed vertebrates (gnathostomes) showing exceptionally 3D-preserved soft tissues in two Carboniferous (300 million years ago) contemporary deposits, 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 evolutionary radiation of modern gnathostomes will be studied using non-destructive imagery technologies (XR Microtomography CT Scan and Synchrotron), which will provide new characters documenting the early stages of the still debated morphological evolution of the vertebrate head skeleton and central nervous system. This axis will be completed by the study of the still unknown processes involved in the fossilization of the 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, and 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 axes, this project on invaluable fossils will provide essential data for the understanding of the evolution of a key organ and for the necessary conditions for its exceptional fossilization.