Belemnites, the squid bullets

digital painting 2024

see a dynamic ichthyosaur chase

Most phylogenetic tree hypotheses place the Belemnitida somewhere around the origin of Coleoidea, the cephalopod group containing octopus, squid and cuttlefish. Therefore, the completely extinct belemnites cannot be reconstructed solely from comparisons with living cephalopods. However, unlike the more basal ammonites, we have a rather certain understanding of the body shape of belemnites, based on excellent fossils including arm hooks and soft tissue (which is generally true also for ammonites, but still lacking enough direct evidence for a consensus about their head morphology).
The two smaller animals in the picture are somehow generalized to depict the common form. The tip between the fins is where the massive rostrum is placed, the frequently found “thunderbolt” as the characteristic organ in front of the internal phragmocone. The big guy below is a representative of aberrant forms with an elongated rostrum, like the giant Megateuthis.