Where Have All the Ammonites Gone?

Ammonites are long gone. The last of their coil-shelled, many-tentacled kind disappeared 66 million years ago in one of the worst mass extinctions of all time. The nearly 10-kilometer-wide asteroid that struck the Earth and drew the curtain on the Cretaceous wiped them out, just as it did the flying pterosaurs and non-avian dinosaurs.