Mineralized Ammonite
Ammonites were nautilus-like organisms that died out when the dinosaurs did. Before then, they were much more successful than the nautiloids in that there were many more ammonite species and they had been around longer. Why the nautiloids survived the mass extinctions at the end of the Cretaceous and the ammonites didn't is anyone's guess. This one is on exhibit in the paleontology hall of the Houston Museum of Natural Science.
Mineralized Ammonite
Ammonites were nautilus-like organisms that died out when the dinosaurs did. Before then, they were much more successful than the nautiloids in that there were many more ammonite species and they had been around longer. Why the nautiloids survived the mass extinctions at the end of the Cretaceous and the ammonites didn't is anyone's guess. This one is on exhibit in the paleontology hall of the Houston Museum of Natural Science.