Asteroceras & Promicroceras, Fossilised Ammonites from Dorsets Jurassic Coast
These ammonites Asteroceras & Promicroceras are superb examples from Dorset’s Jurassic Coast. They are from the Charmouth Mudstone Formation, Black Ven, Dorset. This impressive fossil would make it a wonderful display piece and look good in any collection. The actual ammonite, asteroceras obtuse measures 8cm at its widest. The total weight of the whole specimen is just over 2.7 kilos. These ammonites are from the Jurassic period and are approximately 190 million years old.
Ammonites have been extinct for 65 million years. They are a form of Cephalopod, a group of marine molluscs. These first appeared in the Devonian Period, over 4oo million years ago. As the ammonite grew it added new chambers to the shell, the actual ammonite only living in new and largest chamber. The name Ammonite, derives from from ‘Ammon’ the Greek God. Ammonites were plankton feeders, they also had long tentacles, and swam upright. Altogether, there were in the region of ten thousand different species. Ammonites became extinct 65 million years ago, which was also around the same time as the dinosaurs. The squid and octopus that swim in our seas now however, are closely related. Back to Jurassic Coast Fossils