Definition
Belemnitidae is a family within the extinct order Belemnoidea. These cephalopods lived during the Mesozoic Era. Belemnitidae are characterized by their bullet-shaped internal shells (rostra). These fossils provide important insights into ancient marine ecosystems. They are related to modern squid, and inhabited oceans worldwide. Their extinction marked a significant event in marine history. The family's remains are common in sedimentary rocks.