Biomolecular evidence reveals site-specific embalming recipes for ancient Egyptian crocodiles

Animal mummification, which was central to ancient Egyptian religious practices during the second half of the 1st millennium BC, broadly followed similar principles to human mummification. During this period, crocodiles, often associated with the god Sobek, were mummified in great numbers. Some crocodiles were believed to be living manifestations of the god (sacred mummies), and mummified after their natural death, while others served as votive offerings with large numbers deposited in dedicated burial complexes. Prior research on embalming recipes for crocodiles is limited, but has revealed the use of resins, tars, waxes and bitumen. However, it remains unclear whether embalming recipes varied across mummy types, periods or sites. To investigate this, we analysed seven crocodile mummies from the Late to the Graeco-Roman Periods using gas chromatography–mass spectrometry and correlating molecular profiles with radiocarbon dates and provenance. Our results show that the crocodiles were embalmed with different combinations of beeswax, pine (Pinaceae Pinus ) resin or tar and cedar (Pinaceae Cedrus ) tar. When integrated with previously published data, these results reveal a consistent embalming recipe at Kom Ombo, used over several centuries. This combined dataset highlights the continuity and transmission of embalming knowledge, and the existence of site-specific embalming traditions not documented before.