Fossil fun: ammonites and where to find them
It's a great time of year to get out Fossil Hunting in the UK
Why not start with ammonites?
They're one of the most distinctive fossils
Fossils – evidence of prehistoric life immortalised in stone. Wow!
Recently I’ve done some research for the local museum on one of their exhibits – a fossil ammonite found near Braybrooke 'Castle', Northamptonshire.
Around 200 million years ago during the Jurassic period, this ammonite was alive and swimming round a tropical sea, munching on plankton while trying to avoid being eaten! Think the Caribbean with prehistoric beasties! When the ammonite animal died, it sank to the sea floor, was buried under sediment and became fossilised into the specimen we see today.
And it’s the perfect time of year to get fossil hunting in the UK. So in this post, as well as sharing some ammonite info, there’s detail of where to find them and how to have lots of fossil fun! You’re in with a great chance of making some great discoveries as ammonite fossils are so distinctive and common in the UK.
What is an ammonite?
Living ammonites inhabited the seas 240-65 million years ago colonising virtually all marine habitats to a depth of 800m and probably more. They are closely related to the modern day Nautilus, a pearly-shelled organism which lives at great depths in the Indian Ocean. The ammonite shell was divided internally into chambers with the animal inhabiting the last of these – the body chamber. The creature propelled itself through the sea squirting jets of water out behind it, while controlling buoyancy and movement by regulating gas and fluid within its chambers.
As well as flotation, the ammonite shell’s main function was protection. Adornments such as ribs, spines and knobs may well have helped strengthen the shell but also likely protected the animal inside from predators (e.g. ichthyosaurs, mosasaurs, fish and other ammonites). They may even have been sexual display features!
Ammonites probably fed on small plankton or vegetation growing on the sea floor, perhaps some slow moving animals that crawled along the sea bed (e.g. small crustaceans, young brachiopods, corals) and slow swimming or dead sea creatures drifting in the water.
They are among the most abundant and well known of all fossils. Because of this, their rapid evolution (many different shapes and sizes appearing/disappearing through the ages) and their widespread distribution, scientists use them to date rocks and other fossils. Aesthetically very pleasing with their tightly coiled and externally ribbed shells, they're also treasured by innumerable collectors. Now extinct (wiped out with the dinosaurs 65 million years ago), all we have left of them are these pretty coiled treasures.
Here are some of my ammonite fossils. Scale bars are in mm's:
Due to their snakelike appearance, a legend arose around Whitby, N. Yorkshire, that ammonites were actually sea serpents that were turned into stone by Anglo Saxon abbess St Hilda (614-680 AD). Local collectors and dealers in fossils frequently carved heads on them in order to perpetuate the legend and they became widely known as 'snakestones'. They were also used as charms because they were thought to be a protection against serpents (as well as a cure for baldness and infertility).
However, some people clearly thought they also look like sheep’s horns and the name ‘ammonite’ originates from the name of the Greek ram-horned god ‘Zeus Ammon’. Many ammonites also have names ending in –ceras from the Greek word ‘keras’ meaning horn.
Where to Find Ammonites - Great Fossil hunting locations in the UK
Ammonites have been found worldwide in rocks of Devonian to Cretaceous age, but are especially abundant in the Jurassic and Cretaceous (201 – 65 million years). There are many places in the UK where you can go fossil hunting (see links below), but Dorset’s Jurassic Coast and the North Yorkshire coast are both famous for it.
The Jurassic Coast
Situated along the Jurassic Coast, Charmouth beach is a good place to start. The muddy rocks are chock full of fossils including ammonites. The soft rock of the cliffs gets washed away by the sea, particularly after a good storm, and you can literally walk along the beach and pick fossils up.
Famously, Mary Anning discovered the first complete Icthyosaur here (1810-1811). Although not a scientist herself, her discoveries were some of the most significant geological finds of all time. This, and further sensational finds, changed science significantly. For more info: www.lymeregismuseum.co.uk/collection/mary-anning
Other fossil hunting Locations in the UK
Organised fossil tours
If you don't want the 'do-it-yourself' fossil hunting experience, there are plenty or organised tours including:
The Joy of a new fossil find
I cannot describe how wonderful it is to discover a new fossil - something that no other human has ever set eyes upon. Something that has been entombed in rock for millions of years!
The very first fossil I found was an ammonite fragment on a school trip to the North Downs. The gleaming white chalk of it caught my eye so I picked it off the muddy ground. But my mum threw my ‘lump of rock’ away!
Since then I’ve done loads of fossil hunting, much of it research related. It's fascinating how these, often small, ‘lumps of rock’ can tell us so much. It’s a bit like being a detective; each fossil gives you clues to what life on Earth used to be like. And together these clues build a picture of the past.
Now its down to you... What will you find?
Why not get out there and find something no other person has ever seen. Perhaps you'll make an important scientific discovery like Mary Anning did.
I’d love to hear about your discoveries.
Further Information On Ammonites
The British Geological Survey 'Fossil Focus': http://www.bgs.ac.uk/discoveringGeology/time/fossilfocus/ammonite.html
The ammonite fossilisation process see: https://www.quantumenterprises.co.uk/fossilbeach/whatisafossil.htm
General information: https://en.wikipedia.org/wiki/Ammonoidea