The main objective of the thesis project is to provide an overview of the floristic diversity at the family or generic level (if possible) of the Quercy fossil plant collection conserved at the University of Montpellier II and estimated at about a thousand specimens. Priority will be given to the study of fruits and seeds.

This PhD project is part of the ENLIVEN project, which aims to better understand faunal changes at the Eocene-Oligocene transition. The potential evolution of plant diversity and biomes during this period could have affected the diversity of mammals by modifying their habitat but also their diet. The main objective of the thesis project is to provide an overview of the floristic diversity at the family or generic level (if possible) of the Quercy fossil plant collection conserved at the University of Montpellier II and estimated at about a thousand specimens. Priority will be given to the study of fruits and seeds. The results will be made available online via the Paleobiology Database (PBDB), an online resource for information on the distribution and classification of organisms (https://paleobiodb.org/#/). In parallel, wood fragments will be sectioned, described and identified at generic and/or specific level depending on the number of specimens per species and their conservation. Particular attention will be paid to features linked to plant ecology (growth ring boundary, vessel diameter, etc.) or habit (ray width, etc.). A more detailed taxonomic study will be carried out on one or two families/genera with significant diversity, such as Anacardiaceae, or Vitaceae, which already revealed to be abundant (De Franceschi 2006), or for taxa with an unexpected temporal/specific distribution. - More exploratory, search for palynomorphs and phytoliths will be carried out on several samples from various localities in Quercy. First attempts to find pollen in Quercy sediments were unsuccessful; our efforts will therefore not concern the sediment itself, but will focus on the contents of coprolites. Indeed, dozens of localities have yielded different types of coprolites, most probably produced by insects. They have proven to be good preservatives for pollen at other sites (Winship & Hu 2010). Phytoliths have never been specifically looked for in Quercy deposits, while they can play an important role in the identification of plants at different taxonomic levels. They are especially found in Poaceae (grasses), which can be markers of savannah flora, possibly present during the Oligocene. Finally, the combination of results on taxonomic diversity obtained from the different types of remains will then be integrated into 1) a PFT (Plant functional types) approach and 2) a coexistence approach in order to quantify the climatic parameters under which the vegetation developed. Finally, the combination of results on taxonomic diversity obtained from the different types of remains will then be integrated into 1) a PFT (Plant functional types) approach and 2) a coexistence approach in order to quantify the climatic parameters under which the vegetation developed. An accurate taphonomic study conducted throughout the different parts of the palaeobotanical studies will be crucial to figure out the collection biases and properly interpret the past climate. Finally, the evolution of the local landscape will be put into perspective with 3D dental microwear textural analyses results and compared with shifts in mammalian diversity and diet during the EOT and to other basins.

Scientific Responsible : Anaïs Boura

Application Deadline : 17 March 2023

More information and to apply CNRS Emploi website

Published on: 24/02/2023 17:58 - Updated on: 09/03/2023 17:29