ammonite with a worked mouth - Fossilised animal - cleoniceras - 18 cm - 15 cm

A very important fossil group from the Devonian-Cretaceous period. Totally extinct by the end of the Cretaceous, it is thought to derive from ancestors belonging to the Nautiloidea. Although part of the cephalopod mollusk group, the ammonite is distinctive mainly for the shell shape characterized by bilateral symmetry. The shell is divided into an undivided anterior region where the animal resided and a posterior region divided into chambers. The line of closure between the chambers is highly indicative and facilitates species recognition. Moreover, its outline, in the early forms rather simple and linear, gradually evolved to the more recent ammonites where it is often very jagged and almost baroque. Sizes vary: starting from a few cm but can reach up to 10 cm. Since these are completely extinct marine species, we can only hypothesize their lifestyle. It is believed that forms with smooth external shells were swimmers, often predators. Species with more ribbed and ornamented shells were predominantly benthic. Very beautiful lot, the workmanship of the mouth or living chamber makes this object particularly displayable. In fact, the shaping, smoothing, and carving of the mouth beautifully show the natural crystallization processes of calcite. If illuminated by a beam of light, the ammonite will reveal a very distinctive play of light. Pedestal not included. Happy bidding.