Goniatites were Ammonites alive during the Devonian period 400 million years ago with distinctive zig-zag patterns in the sutures of their shells. These sutures represent the spiraling growth of the shell as the ammonite grew larger during its lifetime. As the shell fossilized, the preservation of the shell creates an array of contrasting colors and patterns as seen on this specimen. Descended from the extant nautilus, Ammonites were cephalopods sharing a common ancestor with squids and octopi. Over 10,000 species may have existed over the Ammonite’s 300 million year existence, and the diversity of these species have helped scientists determine the relative age the rocks they've been found in, as well mark the presence of ancient oceans and seas, such as the North American Great Plains, Antarctica, and the Himalayas.
This Kranaosphinctes Ammonite from Madagascar is approximately 12 inches tall.