Fossils explained 82: Belemnites: Anatomy, ecology, applications

Belemnites are extinct cephalopods that evolved in the early Late Triassic (~240 Ma) and became extinct at the Cretaceous/Palaeogene boundary (66 Ma), at the same time as the extinction of the dinosaurs. Their bullet-shaped internal skeleton, called a rostrum, are commonly found alongside the much more famous coiled ammonites. Whereas ammonites have gone on to become a universal symbol of palaeontology, belemnites are often overlooked by fossil hunters. The intention of this short introduction to belemnites is to furnish a greater appreciation for these fascinating creatures. Not only were they an incredibly important component of Mesozoic marine ecosystems and their exceptionally preserved fossils can tell us much about coleoid diversity throughout geological time, it is their applications that set belemnites apart from other macrofossils. Belemnite geochemistry can provide high-resolution data regarding past ocean chemistry and temperatures. Such information is vital in the reconstruction of Mesozoic climate systems.