News on the World’s Largest Ammonite, Parapuzosia (P.) Seppenradensis (Landois, 1895) together with a New Associated Stratotype Section and Point for the Base of the Campanian

The world’s largest ammonite, Parapuzosia (P.) seppenradensis (Landois, 1895), has fascinated the world ever since the discovery in 1895 of a specimen measuring 1.74 metres (m) in diameter near Seppenrade in Westfalia, Germany. Subsequent findings of this taxon have been exceedingly rare and its systematic position has remained enigmatic. We have revised the historical specimens and documented abundant new material from England and Mexico. Our study (Ifrim et al., 2021) comprises 154 specimens of large (< 1 m diameter) to giant (> 1m diameter) Parapuzosia from the Santonian and lower Campanian, mostly with stratigraphical information. High-resolution integrated stratigraphy allows for precise trans-Atlantic correlation of these occurrences, and the Tepeyac section has become Associated Stratotype Section and Point for the base of the Campanian (Gale et al. 2023). It yields a rich macrofossil assemblage (Ifrim and Stinnesbeck, 2021) which is correlated to other parts of the world by the stable carbon isotope curve, and also to the successin of the German Münsterland Basin where the World's largest ammonite originates. The high- resolution correlation allows for further insight into the palaeobiology, evolution and dispersal of worlds largest ammonite.