Belemnites: A Quick Look

Note: Phil welcomes discussion on this article in the Cephalopod Fossils forum.



Belemnites are probably the most well known extinct cephalopod after the ammonites. They are quite common fossils and have a worldwide distribution. They are a very characteristic and easily recognisable fossil usually resembling a bullet in shape, although this only represents the extreme 'tail' of the animal.

The name 'Belemnite' is derived from the Greek word belemnon which means javelin or dart due to the obvious resemblance in the shape of the fossil. It was a common folklore tale that belemnites were formed from the point of strike of lightning bolts into the ground; hence they are frequently referred to as 'thunderbolts'.

Belemnites are grouped amongst the Order Coleoidea along with the squid, octopus, cuttlefish and argonaut. Belemnites were very squid-like in shape, sharing the same streamlined torpedo shape, but this came about through convergent evolution rather than squids being descended from belemnites. In fact, the closest living relatives to the belemnites are probably the cuttlefish and the strange little squid Spirula, both of which have a chambered internal shell structurally similar to that of the belemnite though in both cases highly modified in their own ways. Although the method of employing a chambered shell for buoyancy control amongst the belemnites is representative of many cephalopod groups, (e.g. Nautilus, Spirula, ammonoids), the use of a counterweight at the rear of the body was an unusual feature.

Coleoids and ammonoids are more closely related to each other than...
To continue reading, and to view / access full images and attachments, please sign in or sign up. You'll gain full access to all TONMO articles, and join the Internet's longest-running cephalopod community! Log in or register now.
About the Author
Phil joined the staff in April 2003. He collects fossils as a hobby, frequently plundering a quarry at Folkestone in the U.K. He has a degree in British archaeology and works for a government department at Dover in England.


There are no comments to display.

Article information

Last update

More in Cephalopod Fossils

More from Phil