Belemnites & Squids
Bullet-shaped guards and ancient squid — belemnoids were the dominant cephalopods of the Mesozoic seas, preyed upon by ichthyosaurs and marine crocodiles.
Overview
This hub covers the coleoid cephalopods — cephalopods with internal shells: the bullet-shaped belemnites of the Jurassic and Cretaceous, and their squid and cuttlefish relatives. Belemnite guards are among the most familiar fossils of the Mesozoic seas.
Quick Facts
Key Characteristics
- •Internal shell: a bullet-shaped calcitic rostrum (guard), the common fossil
- •Pro-ostracum — a blade-like support for the soft body
- •Ten arms, often bearing hooks rather than suckers
- •Fast-swimming, squid-like body with fins and jet propulsion
Fossil Record
Guards are abundant in Jurassic and Cretaceous clays, limestones and chalks of Europe; the Solnhofen Limestone preserves complete belemnites with soft parts, ink sacs, hooks and even the phragmocone intact.
Global Distribution
Global in Mesozoic marine rocks — classic beds in England, Germany, France, Poland and Russia.
Evolutionary & Scientific Importance
Belemnite guards are key index fossils of the Jurassic and Cretaceous, record shifts in ocean chemistry through their isotopes, and their complete specimens revealed the soft anatomy of extinct cephalopods.