What causes the Earth’s climate to change? The Jurassic Period began about 201 million years ago, and the Cretaceous ended about 66 million years ago. The belemnites became extinct at the end of the Cretaceous Period, at roughly the same time as the dinosaurs disappeared. However, we know a lot about them because they are commonly found as fossils, formed when the remains of traces of minecraft mating animals animal became buried in sediment that later solidified into rock.
Belemnites were marine animals belonging to the phylum Mollusca and the class Cephalopoda. Their closest living relatives are squid and cuttlefish. They had a squid-like body but, unlike modern squid, they had a hard internal skeleton. These are the parts that are normally found as fossils.
The rostrum is composed of fibrous calcite crystals arranged at right-angles to the surface. These ‘rings’ represent the growth of the animal, probably over a period of months. As well as the rostrum, strongly curved, sharp hooks made of chitin are sometimes preserved as fossils. These hooks were attached to the belemnite’s tentacles, and were probably used for grasping and holding prey such as other molluscs, small fish and crustaceans. Larger hooks may have been used in mating. Belemnites had ten tentacles, each equipped with 30—50 pairs of hooks.