What is a Belemnite Fossil?

Belemnites were squid-like animals belonging to the cephalopod class of the mollusc phylum. This means they are related to ancient ammonites as well as modern squids, octopuses, cuttlefish and nautiluses. They lived during the Jurassic period (started c. 201 million years ago) and Cretaceous period (ended c. 66 million years ago).

Belemnites became extinct at the end of the Cretaceous period, at about the same time that the dinosaurs were wiped out. We know a lot about them because they are frequently found as fossils. In addition to the scientific information that belemnite fossils offer us, over time a number of myths have emerged around them, and today they remain a fascinating record of Earth’s prehistoric past.

Belemnites resembled squid

Belemnites were marine animals with a squid-like body of leathery skin, tentacles that pointed forwards and a siphon that ejected water forward, which thus moved it backwards because of jet propulsion. However, unlike modern squid, they had a hard internal skeleton.

Reconstruction of a typical belemnite

Image Credit: Dmitry Bogdanov, CC BY-SA 3.0 , via Wikimedia Commons

In the belemnite’s tail, the skeleton formed a bullet-shaped feature sometimes known as a guard, or more correctly, a rostrum. It is these hard parts which are normally found as fossils, since the rest of the animal’s soft tissue naturally decayed after death.

How old are belemnite fossils?

Belemnite fossils can be found in rocks dating from both the Jurassic period (c. 201 – 145 million years ago) and Cretaceous period (c. 145.5 – 66 million years ago), with a few species also being found in Tertiary-dated rocks (66 – 2.6 million years ago). The belemnite guard is bullet-shaped, because it was composed of calcite and tapered to a point. Indeed, the fossils have been called ‘bullet stones’ in the past.

Striking a line west along this dramatic stretch of ever-changing cliffs, Sam and his four legged companion Geronimo, begin their coastal journey at the red cliffs of Exmouth, a location that my have served as a reference point for the Vikings as they made the journey across from mainland Europe and up the river Ex. Moving onwards, Sam explores the very recent history of Branscome where we hear the tale of a shipwreck that caused quite the stir when BMW motorcycles and crates of wine started washing up.

Watch Now

Remarkably, some examples from the Jurassic rocks of southern England and southern Germany have been found with soft parts still intact. In 2009, palaeobiologist Dr Phil Wilby discovered a preserved belemnite ink sac in Wiltshire, England. The black ink sac, which had solidified, was mixed with ammonia to make a paint. The paint was then used to draw a picture of the animal.

The ancient Greeks thought they’d been thrown down from heaven

Owing to their shape, Belemnites take their name from the Greek word ‘belemnon’, meaning dart or javelin. In ancient Greece, the fossils were widely believed to have been thrown down as darts or thunderbolts from heaven during thunderstorms. Some have a finger-like shape, so in folklore have also been nicknamed ‘Devil’s Fingers’ and ‘St. Peter’s Fingers’.

The shark Hybodus with belemnite guards in its stomach, State Museum of Natural History Stuttgart

Image Credit: Ghedoghedo, CC BY-SA 3.0 , via Wikimedia Commons

Like many fossils, belemnites have been said to have medicinal powers. Different regions have different traditions; however, they have been used to treat rheumatism, sore eyes and intestinal stones in horses.