An unpublished manuscript by Jacques-Amand Eudes-Deslongchamps describes the remains of two species of fossil crocodyliforms attributed to the genus Steneo-saurus Geoffroy Saint-Hilaire, 1825. It is demonstrated that these notes give detailed explanations of three engravings that were executed under the direction of Étienne Geoffroy Saint-Hilaire in 1831. These plates represent remains of Steneosaurus megistorhynchus Geoffroy Saint-Hilaire, in J.-A. Eudes-Deslongchamps, 1866 and Teleidosaurus calva-dosii (J.-A. Eudes-Deslongchamps, 1866). Written before 1837 and likely between June 1831 and June 1832, this work would be the oldest study on thalattosuchians from Normandy, known to date, by Jacques-Amand Eudes-Deslongchamps. This document prefigures the quality of his future works on fossil crocodyliforms that he published more than thirty years later. An extensive excerpt from this document has been used by his son, Eugène Eudes-Deslongchamps, in his Prodrome des Téléosauriens du Calvados published in 1869. An unrecorded drawing found in the archives of Georges Cuvier housed in the central library of the Muséum national d’Histoire naturelle, Paris is also presented. This drawing represents the mandible and the anterior extremity of the upper jaw of the first specimen of Teleosaurus cadomensis (Lamouroux, 1820) . These remains, discovered in 1817, were prepared by Jacques Amand Eudes-Deslongchamps between 1826 and 1830. All of these documents shed light on the first studies of one of the major players in vertebrate paleontology at a time when this science was still in its early stages.
Fossil crocodyliformes, Thalattosuchia, Eudes-Deslongchamps, Geoffroy Saint-Hilaire, Normandy, Bathonian, History of paleontology.