Supported projects

The terrestrialisation of tetrapods during the Palaeozoic represents a major step in vertebrate evolution, which is still largely approached through skeletal transformations alone. Adaptations of soft tissues, although crucial for respiration, reproduction and sensory perception in a terrestrial environment, remain poorly understood owing to their low preservation potential in the fossil record. Among these, the evolution of the visual system, which plays a central role in tetrapod ecology, remains particularly poorly documented. Amphibians constitute a key model for investigating these transitions thanks to their metamorphosis, which induces profound remodelling of the skin and eyes during the shift from an aquatic to a terrestrial lifestyle. Recent discoveries in dissorophoid fossil amphibians from the Late Carboniferous (~305 millions years ago) reveal exceptional morphological preservation (pupil shape), as well as chemical signatures associated with the eye (zinc enrichment) and the orbital region (arsenic), suggesting the preservation of ocular pigmentation and the indirect presence of soft tissues such as the eyelid. Using advanced imaging methods (elemental mapping by X-ray fluorescence and synchrotron X-ray absorption spectroscopy, and multispectral imaging in particular), this project aims to characterize in detail the morphology and chemical composition of the visual system in fossil and extant amphibians at different ontogenetic stages. By developing and validating morphochemical proxies for ocular tissues, this project aims to reconstruct the evolution of the visual system in amphibians and their ancestors, and to assess its role in their life cycle, metamorphosis, and adaptation to terrestrial life.