PhD Student

Margot LOUAIL
PhD Student, Palevoprim

Thesis topic

Dental archives and feeding habits in the past: contributions from experimental approaches

During the Cenozoic, changes in dental morphology are observed in several mammalian clades, such as ruminants, suids and hominins. These modifications are often considered to reflect adaptations to increasingly abrasive diets associated with the progressive aridification and opening of environments. The Late Pliocene and Early Pleistocene constitute a key period in the evolutionary history of hominins. It is notably characterized by an important taxinomic diversity including gracile and robust forms. Different strategies developed during periods of food scarcity would help explain this diversity and the ecological niche partitioning among contemporaneous taxa. They thus shed light on the factors that have favored the selection of robust craniomandibular and dental phenotypes. However, the past ecologies of Plio-Pleistocene hominins remain poorly understood. In order to refine our interpretations of the variations of craniomandibular and dental ecological proxies to understand past ecosystems, an experimental model using an omnivorous bunodont mammal is developed. Hence, this thesis is based on nearly 200 domestic pigs distributed in about thirty different controlled-feeding experiments. Different craniomandibular and dental proxies are studied: micro- and meso-wear, biogeochemistry of enamel and mandibular morphology. This work highlights the potential of these proxies to detect the consumption of small to moderate proportions of food resources with physical and mechanical properties similar to those of foods potentially targeted by early hominins during period of food scarcity (fallback foods): seeds, herbaceous plants, C4 plants, animal matter and underground storage organs. Moreover, some resources seem to leave more traces than others on cranio-dental archives, and seem to generate more constraints on mastication and dental abrasion. The results obtained allow us to propose future developments for a better calibration of these ecological proxies, as well as to test these experimental observations on extant wild taxa. The dental microwear analysis of extant suids, in light of the experimental results, highlights relatively subtle differences in feeding habits. Paleoecological inferences are then proposed for Kolpochoerus from the Shungura Formation (Plio-Pleistocene, Ethiopia) based on their dental microwear. This thesis contributes to a better understanding of the behavior of frequently used ecological proxies following the consumption of different resources, and provides new insights to refine our paleoecological inferences.

Illustration ARySQUE

Place

Amphi PBS, Bât. B36, Université de Poitiers.

Jury

• Marie BALASSE (Rapporteure), Directrice de Recherche, MNHN, Paris
• Sireen EL-ZAATARI (Rapporteure), Enseignante-chercheuse, Université de Tübingen
• Allowen EVIN (Examinatrice), Directrice de Recherche, ISEM, Montpellier
• Klervia JAOUEN (Examinatrice), Chargée de Recherche, GET, Toulouse
• Juan José IBÁÑEZ (Examinateur), Directeur de Recherche, Archaeology of Social Dynamics-CSIC, Barcelone
• Xavier MILHET (Co-encadrant), Maître de Conférences, Institut Pprime, Poitiers
• Antoine SOURON (Co-directeur), Maître de Conférences, PACEA, Bordeaux
• Gildas MERCERON (Directeur), Directeur de Recherche, PALEVOPRIM, Poitiers