Belemnites – a bullet-shaped cephalopod

(bell-em-night-tees)

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Model of Belemnites.
Image: Jon Augier
Source: Museum Victoria

Fossil of Belemnites semihastatus.
Image: Jon Augier
Source: Museum Victoria

Jurassic

HOW BIG IT WAS

Belemnites relative size depiction as described below
This fossil guard from Belemnites is approximately 14cm long.

Belemnites were a group of cephalopods resembling squid, and are related to the modern-day cuttlefish. They first appeared about 360 million years ago, but were most abundant in the Jurassic and the Cretcaeous, becoming extinct at the same time as the dinosaurs. This species, Belemnites semihastatus, had an ink sac and ten arms like other members of the belemnites.

Although fossils of their chambered internal shell called the phragmacone and small hooks that lined their grasping limbs have been found, the most commonly found remains of belemnites are the bullet-shaped structures called guards. These were also internal structures, and they formed the tip of the phragmacone at the ‘tail end’ of the animals.

A TRAIL THROUGH TIME

Cephalopods first appeared in the Silurian and survive to this day. See how this group has changed over time.

NautiloidsPtenoceras GoniatitesParalegocerasCladiscitesBostrychoceras

WHERE IT WAS FOUND

map for belemnites

This fossil of Belemnites semihastatus was discovered in Germany.

RELATED OBJECTS

Other objects from the Jurassic

ArchaeopteryxGlyphea