Cleoniceras ammonite excavated in Madagascar the cleoniceras type ammonite has been prepared, cut in half and polished revealing the wonders of mineralisation which takes place over millions of years. Each chamber has been replaced with quartz in the form of calcite, minerals that surround the animal's shell when covered over in the silts of the Cretaceous period seas contain the chemical elements that create the colours now millions of years later preserved.
This ammonite is very large and fine for the type and the fossil deposit location, making this a superior ammonite of type. The colouration and the mineral infill of the chambers are quite fine. An overall exceptional specimen ammonite of the Cretaceous period. Highly recommended.
Ammonites are part of the Ammonitida of marine invertebrates. These were fascinating creatures from the deep oceans and believed to be aggressive creatures like some giant squids today. With extremely large eyes and remarkable vision, they could hunt their prey at great depths where little light penetrates the ocean depths. The Cephalopod would grasp its prey using long tentacles, much as the persisting modern-day Nautilus Pompilius which can still be found extant in the modern-day Pacific. The nearest living extant relatives to ammonites are living coleoids, octopuses, squid, and cuttlefish.
A few years ago off the Great Barrier reef at depths between 200 to 400 meters, sightings of the Nautilus Pompilius were made, showing the pressures these Cephalopods can attain. The Ammonites extinction is dated around 65 million years. Ammonites are important Index Fossils, it is often possible to link the sediment layer in which they are found to specific geological time periods. The largest ammonite discovered to date is around 2.5 meters in diameter from Germany.