Ammonites survived cross the Cretaceous–Paleogene boundary

PUBLICATION — Machalski, M., Olszewska-Nejbert, D., Landman, N.H., Jagt, J.W.M., Garb, M., Milàn, J. 2025. Ammonite survival across the Cretaceous–Paleogene boundary confirmed by new data from Denmark. Scientific Reports 15,45802 (2025). doi: 10.1038/s41598-025-34479-1

Rycina: Ammonite specimens representing the genera Baculites (a, b, e, f), Fresvillia (c, d), and Hoploscaphites (g) from lower Danian deposits exposed at Stevns Klint, Denmark (see Fig. 3 in Machalski et al. 2025). Prasinophytes belong to the green algae.

Ammonites, extinct cephalopods dominant in Mesozoic marine ecosystems, are often listed amongst victims of the end-Cretaceous mass extinction (66 Ma). Claims of their local survival across the Cretaceous–Paleogene boundary have faced scepticism from parts of the palaeontological community. This study provides strong evidence, based on taphonomic and sedimentological analyses, that ammonites preserved in the lowermost Paleogene deposits in Denmark, survived for at least tens of thousands of years after the Chicxulub impact, thought to have triggered the extinction. This opens new avenues of research, raising questions about what actually killed the last ammonites.

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