Ammonites are an extinct group of marine mollusk, their name given by Pliny the Elder because of the resemblance to the ram’s horns of Ammon, the Egyptian god of life and procreation. Widespread and diverse in Jurassic and Cretaceous periods, ammonites soon died out, but have been found world wide. Ammonites are part of the cephalopod family, along with Nautiloids (shell dwelling creatures) and Coleoids (shell-less mollusks, like squid and octopuses). Ammonites were born with one tiny shell and built new chambers as they grew – thereby creating the segmented shell that can be seen here in this fine example. They would have moved into the new chamber, sealing off the older, smaller chambers – these older chambers were also filled with gas, allowing the ammonite to control its buoyancy. Ammonites first appeared around 450 million years ago, during the Paleozoic Era, and became extinct around 66 million years ago, at the end of the Cretaceous period. The last ammonites became extinct at the same time as the dinosaurs, in a mass extinction called the Cretaceous-Paleogene extinction, which is believed to have been caused by an asteroid colliding into Earth.
Block of Ammonites and Fossilised Shells
A cluster of well preserved ammonites and shells embedded in a stone. A beautifully complex and delicate fern like patterns is visible across some of the ammonites preserved here – the central bottom, bottom right, top right and the two smaller ammonites on the very top left. These are referred to as suture lines, and are used to identify ammonite types. The complicated patterns evident here – patterns often compared to that of an oak leaf – are characteristic of the cleoniceras genus of ammonite. The distinctive nature of these suture lines are especially prevalent when compared to other, more traditional ammonite suture lines such as the lower top left.
The cleoniceras ammonites were a genus of the Hoplitidae family, which appeared during the Cretaceous period, around 115 million years ago. Along with all other ammonites, these became extinct in the late Cretaceous period, around 66 million years ago. Cleoniceras Ammonites have often been found in Madagascar. This example has been finely polished to clearly display and showcase the exterior of each ammonite and shell. Some of the shells also display beautiful iridescence.
Period: Cretaceous period
Condition: Fine condition. There are minor cracks on some of the ammonites. Some of the shells are not complete.
|Dimensions||L 51 x W 50 x H 18 cm|