Ammonites first appeared around 240 Million years ago during the Triassic period. They descended from straight shelled Cephalopods, Orthoceras being a well known species characterised by its long straight chambered body. Ammonoids and their relatives in general, go all the way back to the Devonian, so by the time the Triassic came around, there was many well evolved species of Ammonite in existence. It is thought that the Permian extinction, 252 Million years ago, may have given the newly formed ammonite species a helping hand in becoming so prolific. At the end of the Permian, some 96% of all marine life, and 70% of terrestrial life became extinct. It is one of the worst extinction events the world has ever experienced. At the end of the Triassic era, only one species of ammonite survived. Amazingly, from this one species, they began to thrive again and became widespread during the Jurassic and Cretaceous. It was at the end of the Cretaceous that ammonites, along with dinosaurs and many other species finally became extinct. The Nautilus, a cousin of the ammonite however, survived and is frequently found in the warmer oceans of the world today.
Nautiloids from China Trilacinoceras hunanense is an extinct genus of Nautiloid. This fossil dates back to the Ordovician times. Found in Zhangjiajie, Hunan, China. It has been prepared on its matrix rock, and polished to a high quality finish. Ideal for the collector who wants something really different.