Parapuzosia seppenradensis is the largest ammonite to ever exist. It existed in maritime habitats in what is now Westphalia, Germany, during the Lower Campanian Epoch of the Late Cretaceous period. A specimen measuring 1.8 m (5.9 ft) in diameter was discovered in Seppenrade, close to Lüdinghausen, Germany in 1895; nevertheless, the living chamber is not fully developed. The original fossil is on display at Münster, Germany's Westphalian Museum of Natural History entryway. This specimen's diameter was formerly believed to have been 2.55 m (8.4 ft) or maybe 3.5 m (11 ft) if it had been complete. The biggest specimens, according to a research conducted in 2021, had a diameter of almost 2 meters (6.6 feet). The projected total living mass is 1,455 kg (3,208 lb), of which 705 kg (1,554 lb) would come from the shell.
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A Parapuzosia seppenradensis shell compared to a human.
A reconstruction of Parapuzosia seppenradensis.