L’étude inachevée d’Étienne Geoffroy Saint-Hilaire sur les crocodiles fossiles (Thalattosuchia) de Normandie à la lumière de documents inédits

Abstract

An unrecorded manuscript dated 30 May 1831 shows that Étienne Geoffroy Saint-Hilaire was making drawings and engravings of three new species of fossil crocodiles (Mesoeucrocodylia, Thalattosuchia) from the Jurassic of Normandy (France). The three species are named Steneosaurus aubignensis, Steneosaurus quillensis and Teleosaurus microtrèmes. Geoffroy Saint-Hilaire was planning to publish a detailed descriptive work on these “grands sauriens fossiles de Normandie” that he saw during two successive visits in Caen (Normandy) in late 1830 and early 1831. Unpublished letters housed in the Library of Caen and The American Philosophical Society, as well as publications of Geoffroy Saint-Hilaire allow to trace the different steps of this project that he planned to achieve in close collaboration with Jacques-Amand Eudes-Deslongchamps. This project never saw the light of day. Based on the specimens which Geoffroy Saint-Hilaire had knowledge then, the first two new species are shown to correspond to Teleidosaurus calvadosii and Steneosaurus megistorhynchus, respectively. It is also shown that Teleosaurus microtrèmes represents the new name that Geoffroy Saint-Hilaire wanted to choose for Teleosaurus cadomensis, in order to replace the specific name proposed by Lamouroux in 1820. Finally, based on the details given by this unrecorded document, the never published engravings ordered by Geoffroy Saint-Hilaire have been discovered in the personal library of Georges Cuvier housed in the library of the National Museum of Natural History, Paris. These long-lost and unrecorded plates are figured and described for the first time.