The suture line of Rossalites superbum is clearly visible in this fragment. It is this zig zag pattern which characterizes the ammonites on the whole, and each species has its own pattern. Like fingerprints, ammonite experts use this suture line pattern to identify species of ammonites, especially where only fragments are available. One of his characteristics were ram's horns behind each ear. Most ammonites are more or less spiral, and some indeed resemble ram's horns.
Ammonite extinction is a hotly debated topic.
The basic fact is that no ammonites are known beyond the end of the Cretaceous, while the other cephalopod groups, the coleoids and nautiloids, survive to the present day. The best known victims were the dinosaurs, but other groups vanished too, including many forms of plankton, pterodactyls, mosasaurs, rudist and inoceramid bivalves. Meteoritic impact is currently the theory favoured by many geologists for explaining all these extinctions. A crater in Yucatan, Mexico appears to have been formed at the right time, and such an impact, the proponents say, would have had a profound affect on the world's climate. One effect would be cutting off sunlight for months, maybe years, killing off many of the planktonic plants upon which the economy of the sea is based.