Parapuzosia

Parapuzosia seppenradensis is the largest known species of ammonite.Payne, J.L. et al 2009. Two-phase increase in the maximum size of life over 3.5 billion years reflects biological innovation and environmental opportunity. PNAS 106(1): 24–27.  It lived during the Lower Cretaceous, in marine environments in what is now Germany. 

A specimen found in Germany in 1895 measures  in diameter. The front chamber where the animal lived is damaged. Presumably, a large predator bit the end off and the living ammonite taken with it. Almost all ammonite fossils have this damage to the 'living chamber'.

If complete, this specimen would have had a diameter of about  or even .Teichert C. & B. Kummel 1960. Size of endoceroid cephalopods. Breviora Museum of Comparative Zoology 128: 1–7. The total live mass has been estimated at , of which the shell would be about .

 References 

Category:Ammonites