Giant ammonite (Parapuzosia seppenradensis)

Cretaceous, 85 million years old, Gosau, Austria

This was the largest known ammonite and could grow up to three meters in diameter. Ammonites, like the dinosaurs, became extinct 66 million years ago, at the end of the Cretaceous period. The cause of the extinction was most likely the impact of a large asteroid on Earth, which resulted in the Chicxulub crater in Mexico.