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PhD Defense - Thomas BERTIN

Dynamics and evolution of tooth replacement in amniotes.
When Dec 20, 2018
from 01:30 PM to 04:30 PM
Where Salle des thèses CRC Monod Campus
Contact Name Thomas BERTIN
Attendees Laudet, Vincent, PU Sorbone Université Rapporteur
Tucker, Abigail, Professor, King’s College of London Rapporteure
Farges, Jean-Christophe PU-PH, Université Lyon 1 Examinateur
Tafforeau, Paul, Chercheur ESRF Examinateur
Vico, Laurence, DR ISERM, Université de Saint Etienne Examinatrice
Viriot, Laurent, PU, Université Lyon 1 Directeur de Thèse
Thivichon-Prince, Béatrice, MCU-PH Université Lyon 1 Co-directrice de thèse
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Summary

Dental replacement consists in the formation of a new tooth which will take the place of a former tooth, allowing for a renewal of the dental tissues as well as their environment (periodontium). Because of the strong link between the replacement of the teeth and periodontal tissues, I explored among extant and fossil amniotes the diversity of tooth replacement, attachment and implantation modes. This work presented two objectives: to clarify the terminology associated with replacement, implantation and attachment and to review the current knowledges and hypothesis concerning the diversity and the evolution of the three features. In a second part, I studied continuous tooth replacement in archosaurians. First we characterized the dentition and teeth of two representatives of the last groups of toothed-birds, Hesperornis and Ichthyornis. Second, I studied the mechanisms of dental development and replacement in the Nile crocodile embryo, through X-ray microtomography and Notch pathway gene expression study. We observed successively two types of teeth, surface and submerged teeth, which present a very similar development at morphological and molecular level. The main difference is the interruption of the development in the surface teeth. In a third part, I investigated one alternative to continuous tooth replacement in the common warthog that presents different adaptations of its dentition to highly abrasive diet because of the teeth mesial drift, and all the physiological processes associated with. Thus dental replacement has been achieved by different mechanisms throughout evolution. The study of tooth replacement encompasses different phenomenon that must be studied through both development and evolution to comprehend them.