The name ammonite, from which the scientific term was derived, was inspired by the spiral shape of their petrified shells, which somewhat resembles the twisted horns of ram. Pliny, the Elder, in the year 79 AD, according to the Julian calendar, called fossils of these animals Ammonis cornua (horns of Amun), because the Egyptian god Amon was depicted with the horns of ram. The name of ammonite genera often ends with -ceras, which in Greek means ‘horn’.
Originating from the early Nautiloids, Ammonoid Cephalopods first appeared in Devonian, about 400 million years ago and became extinct at the end of Cretaceous, 65 million years ago, along with the dinosaurs.
The classification of Ammonoids is partly based on the ornament and the structure of the partitions of shell chambers. While all the nautiloids exhibit soft curved seams, the ammonoid seam line (the intersection of the partition with the outer shell) has…
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