On Leonardo and a fossil whale: a reappraisal with implications for the early history of palaeontology

A recent reappraisal of two passages in Leonardo da Vinci’s Codex Arundel, in which the then young Leonardo reports on visiting a cave and on some sort of ʽmarine monster’, has led to the proposition that Leonardo observed and wrote on fossil remains of a whale preserved in a cave. Whereas this hypothesis appears reasonable overall, some problems persist in accepting the purported location in which Leonardo would have observed the fossil. Here we provide a new analysis of the aforementioned passages by Leonardo which allows us to confirm that Leonardo saw a fossil whale and recognised it as such. However, his observation did not occur in a cave, but likely along the flank of a hill, as relatively common for Tuscan Pliocene fossil cetaceans. Leonardo seemingly made taphonomic observations on the fossil whale and inferred that a considerable amount of time must have passed from the death of the whale in the sea to allow for its eventual discovery on land–an observation that likely contributed to shaping Leonardo’s later thoughts on sedimentation and fossilisation. This might represent Leonardo’s earliest text devoted to a palaeontological theme. Moreover, it comprises the first known description of a cetacean fossil.