Wednesday, 16 September 2009

Of Ammonites and Belemnites

Ignoring jokes from Partner-who-loves-tea about me being a living fossil there are two fossils on display in our house. One is small ammonite. These are probably the most commonly found and best known fossil.

The second is a larger and, in my view more interesting, Belemnite - probably the most well known extinct cephalopod after the ammonites. Belemnites were squid-like carnivores with a soft body around an internal, pencil-shaped shell. Early forms evolved in the Carboniferous period and are thought to have evolved from the same ancestors as the ammonites. Belemnites were common from the Lower Jurassic period to the end of the Cretaceous period and became extinct at the same time as the dinosaurs - approximately 65 million years ago. 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 for many centuries that belemnites were formed from the point of strike of lightning bolts into the ground; hence they are frequently referred to as 'thunderbolts'. Zeus is often depicted throwing a thunderbolt which looks very much like a Belemnite fossil.

The idea of the belemnite shape obviously gave rise to the name of this aircraft – the Thunderbolt.

The cuttlefish is the modern-day relative of the belemnite. Belemnites were efficient carnivores that caught small fish and marine animals with their tentacles, and ate them with their beak-like jaws. Their tentacles were different to the modern squid, as they had hooks instead of suckers to grab prey. They were built for speed and probably lived in shoals and fossil evidence shows they formed a major part of the diet of ichthyosaurs.



  1. This is what I love about blogging!! I learn so much in the course of a visit!!!
    Hope it has stopped raining in your area.

    Love Granny

  2. Like I said before-- coming to your blog is like opening Christmas presents-- you know there will be something great inside, but you never know what it will be.

  3. Thanks for adding to my store of 'useless' (!) information! LOL...

  4. your link had dropped of my page and lve only been visiting your words, words, blog....glad I dropped by this is fascinating...more please..

  5. Thanks all, especially Tricia - that really is the nicest compliment I've ever had while blogging and it's knowing how much it is appreciated that makes it such fun to do.

  6. This was fascinating! A few hours after I read it, we were watching an episode of "Nature" which talked about cephlapods (sp?) like the cuttle fish, and I felt quite smug, with the inside information I'd gleaned from reading your post. Thank you!
    The Canadian Chickadee

  7. Yes. I second Tricia on this one. I sometimes wish that I could have an original thought like that. I probably have had at some time but, if so, I've forgotten what it was.


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