14th October 2020 is National Fossil Day and it also happens to be my 60th birthday. As the palaeontologist for National Museum Northern Ireland, and with a fossil obsession spanning more than 53 years, it seems that now might be the time to write something about my relationship with one particular group of fossils.
Not all fossils are equal. You can keep your dinosaurs and mammoths – for me the best fossils of all are ammonites, extinct spiral-shelled sea creatures related to the modern squid and octopus. They show great variety, with smooth to intricately ornate shells from less than a centimetre across to giants spanning more than two metres. Ammonites are popular fossils among collectors, although exactly why this should be is not clear. Perhaps it is the aesthetics of their beautifully regular spiral shape. Who knows? Must be something deep in the subconscious…
I found my first fossils in the family garden near Cheltenham in August 1967, a couple of months short of my seventh birthday. To me they were strange ‘patterny stones’ but my dad told me that they were fossils and had lived millions of years ago.
From my first fossil book I discovered that they were Jurassic rhynchonellid brachiopods, but that little book contained pictures of many other fossils of which trilobites and ammonites seemed the most exciting (if we exclude dinosaur bones, which I didn’t think I was likely to find). The Jurassic rocks around where I lived were not old enough to contain trilobites but there should be ammonites to discover, and I still remember the excitement at finding my very first ammonite a few weeks later. Even though it was less than 2 cm across and rather waterworn, it started a life-long love affair with these fascinating fossils.
By the early 1970s I realised that the Lower Jurassic, or Lias, clays beneath the Severn Vale were a rich source of ammonites, and that building sites, pipeline trenches and landfill sites were the places to look. I spent many a happy evening in the summer of 1972 picking over piles of clay on a local building site ten minutes walk away, and built up quite a collection of different types.
Then, in 1973, a pipeline trench came ‘marching’ across the fields nearby. Today such trenches are usually dug and filled the same day, but back then the trench was left open for weeks, allowing rain to gently wash fossils out of the clay dumped to one side. Following this for a couple of miles I realised that the types of ammonite I was finding changed as the trench gently ascended the valley side. Each clay layer is a particular age, with higher layers younger than the lower ones, and because ammonites were evolving through time so successive groups of layers contain different ammonites. Think of it rather like a book; if each clay layer is a page, then an ammonite species might represent a chapter spanning several pages or layers.
From this moment my ammonite hunting suddenly became a whole lot more interesting! Cycling around the Gloucestershire countryside in the mid-1970s it was always thrilling to come across a new patch of freshly exposed clay. There was always the prospect of coming across a really nice specimen, or a species of ammonite that I had not found before, but even a few fragments were usually enough to tell me which ammonite ‘chapter’ (geologists call them ammonite zones and subzones) might have been uncovered and this was often sufficient reward for my pedalling exertions.
Many of the ammonite species I found on my perambulations became familiar friends, although with names like Oxynoticeras, Liparoceras, Amaltheus or Cheltonia (yes, named after my home town of Cheltenham!) they are unlikely to be familiar to most people. For more than a decade I criss-crossed the Gloucestershire countryside on my bike, mapping out the ammonite zones and subzones I recognised at every new site I came across. Each patch of clay was significant, but there were some real highlights too.
At one site, near Gloucester, several large holes had been dug for landfill and, when I stumbled across it in the summer of 1979, the heaps of clay had been exposed to the weather for months. Literally thousands of small ammonites had been washed out by the rain and lay scattered across the surface. Many of these little ammonites were preserved as iron pyrite, or ‘fool’s gold’, so it was like an Ammonite Eldorado! But it was a landfill site too so, inevitably, there were seagulls. Unfortunately, seagull poo sometimes has a spiral shape and is similar in size and colour to many of the ammonites I was finding. All that glitters was not necessarily a fool’s gold ammonite…
What might seem a somewhat esoteric pastime proved its worth in 1982 when the British Geological Survey set about revising the geological map of the area around which I had been cycling. My maps and data helped them to pick out some major geological faults cutting across the seemingly featureless clay vale, identified where ammonite zones (‘chapters’) that were widely separated in time were unexpectedly juxtaposed at the surface. Subsequently most of these ammonites, and my maps and data, were donated to the British Geological Survey and my schoolboy observations were later published in a paper in a local Gloucestershire journal.
As a student at Bristol University in the early 1980s I found many new sites to explore in search of ammonites and other fossils, and storage space became scarce in my rather small student room.
On one occasion my bike was so loaded down with ammonites (actually one large ammonite in bits) that I barely made it back after two spokes broke on my rear wheel.
Obsessed with ammonites, I had pictures of some of my favourites arranged in an evolutionary tree on the ceiling of my room. Even after sitting the last of my final year exams (a 3-hour practical exam on fossils) I headed off on the bike again to look for still more ammonites on nearby Dundry Hill. I suspect that some of the other students thought I was a bit weird…
Fast forward more than a decade to 1996 and I found myself as Curator of Palaeontology at the Ulster Museum, but in a land where Jurassic rocks are pretty thin on the ground. However, what Northern Ireland lacks in quantity it makes up for in quality. The shore at Waterloo Bay, on the outskirts of Larne, proved particularly interesting and unexpectedly rose to international importance when it was realised that the rocks here, from the very start of the Jurassic Period, were thicker and contained better preserved ammonites than rocks of the same age anywhere else in the UK. It’s rather like having more pages in each chapter, and with better pictures, so it gives a more detailed story.
But my most regular ammonite-hunting pilgrimages are to White Park Bay, on the north coast. The Lower Jurassic clays there are exactly the same age as those near where I grew up in Gloucestershire and so they contain some of the same species of ammonites that I used to find as a schoolboy. Finding them here is like meeting old friends, ammonites that I know and love from back in Gloucestershire, but there are strangers among them too. Some are just species that I had never found back home but, among more than forty different ammonite species and more than 200 actual specimens (all of them added to National Museums NI collections) that I have found over the years, there were two that proved to be new not just to me but to the whole of science.
One of these new species is tiny, less than 14 mm across even when fully grown, and has an almost entirely smooth shell. It’s not very exciting to look at which is why it was several years before I recognised it for what it was. Although new to science, it is closely related to one of my ‘old friends’ from Gloucestershire (a small ammonite called Cheltonia acciptris) and, in collaboration with fellow ammonite enthusiast Murray Edmunds, it was named Cheltonia howarthi after a distinguished ammonite expert.
The other new ammonite species (actually collected by Rob Raine from the Geological Survey NI) is quite different – a fat knobbly ammonite about the size and shape of a golf ball. It is similar to one that Murray found in the Hebrides, a region that was once part of the Kingdom of Dalriata encompassing the western edge of Scotland and north-east corner of Ireland, so we named it Vicininodiceras dalriatense. Try saying that with a mouthful of cornflakes.
These little ammonites are scientifically important, and a unique part of Northern Ireland’s natural heritage, but they seem hardly likely to set the pulse racing of all but the most ardent ammonitophile. But for those poor souls less stricken with ‘ammonite fever’ the Ulster Museum has on display some specimens that cannot help to impress.
Perhaps the most extraordinary is a slab barely 50 x 30 cm across covered with more than 300 ammonites, large and small, and several pieces of fossil driftwood. When found on the Dorset coast, near the famous fossil location of Lyme Regis, this was just a grey rock with a few ammonites poking out at the edges. It was the skill and experience of fossil preparator Andy Cowap, and several hundred hours carefully picking away the hard limestone that revealed this astonishing snapshot of an ancient sea floor.
Another stunning specimen, also from Lyme Regis, has just four large ammonites beautifully arranged and with a bonus Nautilus at one end; it’s the picture at the start of this blog. Unlike ammonites, Nautilus are still with us today. They have a coiled shell like their cousins the ammonites, but I just can’t get excited about them (although I was once quite excited about a huge Nautilus I found in 1974). Whereas ammonites were evolving at a hectic pace, Nautilus seems to have done nothing with its life. Those alive today really don’t look much different from those that were living in the Jurassic, and they lack all of those ribs, ridges and knobs that make ammonites so interesting to look at and to study.
But my favourite of the museum’s ammonite on display is not any of these. It’s of a type called Titanites that, to me, is the most elegant of all ammonites despite the huge size they often reach (half a metre or more). Titanites is found in the Portland Stone of Dorset, the same rock from which the original Ulster Museum is built so there is a connection there. The museum has several in its collections, with the nicest of them in a key position in our Fossils and Evolution gallery, but I just can’t resist them and have several of my own in our garden and even two in the Living Room.
My wife sometimes asks me how many ammonites I need, particularly when I come home with yet another one of those enormous Portland ammonites. What sort of a question is that? You can never have too many ammonites! How dull our lives would be without them…
Dr Mike Simms, palaeontologist and Senior Curator of Natural Sciences, National Museums Northern Ireland - 14th October 2020