AMMONITE QUESTIONS ANSWERED: SHELLS, SPIRALS AND ANCIENT TIMEKEEPERS

A spiral in stone can stop you in your tracks. Follow its curve and the questions arrive almost immediately. What lived inside? Why the ribs? And how can a shell tell us anything about the age of a rock?

Ammonites reward that curiosity. Their fossils preserve clues to ancient animals, vanished oceans and the passage of geological time. 

Here are ten questions to start your exploration, with a few favourite Fossil Huntress stories along the way.

WHAT WAS AN AMMONITE?

Imagine a sea animal with a soft body, arms around its mouth and a shell it carried wherever it went. That was an ammonite! 

Many ammonites had a shell curled into a spiral, a little like a tightly rolled garden hose. Some shells had ridges or spines, while others were much smoother.

Ammonites were relatives of today’s squid, octopuses and cuttlefish. These animals belong to a group called cephalopods. Ammonites are extinct, which means none are alive today. We learn about them by studying their fossils.

Inside the shell was a row of little spaces called chambers. Think of rooms separated by thin walls. The ammonite’s soft body lived in the largest room, near the shell’s opening. As it grew, it added a bigger room and closed off the old one behind it.

The older chambers held gas and some liquid. Together, they helped the ammonite stay afloat in the sea instead of sinking to the bottom. Scientists call this buoyancy. Its shell was both a protective home and part of its floating equipment!

For a look inside, visit Ammonites: Chambered Beauty, now illustrated with examples of chambered shells and different coiling patterns.

CAN I MEET A LIVING AMMONITE?

Only in your imagination. Ammonites are extinct, with most disappearing during the mass extinction about 66 million years ago. The fossil shell in your hand is evidence of an animal whose world has gone.

IS A NAUTILUS AN AMMONITE THAT SURVIVED?

A tempting thought, but no. A living nautilus also has a chambered shell, yet it belongs to a different cephalopod lineage. Similar shells do not make the animals interchangeable.

Meet these living shelled cephalopods in Nautilus: Nautilidae.

HOW CAN I TELL WHETHER A FOSSIL IS AN AMMONITE?

Begin by observing rather than naming. Look for the overall shell shape, ribs or other ornament, visible chambers and suture lines. Examine both sides and the edge when possible. Record its size and what is known about the rocks it came from.

A spiral is a clue, not a verdict. Other shells and natural forms can resemble ammonites, and incomplete fossils may need a specialist’s eye. Compare the examples in Chambered Beauty before settling on an identification.

WHY DO SOME AMMONITES LOOK LIKE HOOKS OR KNOTS?

The familiar flat spiral was only one possibility. Heteromorph ammonites developed open coils, hooks, helical forms and extraordinary bends. These were characteristic growth patterns, rather than shells that accidentally went wrong.

Explore Heteromorph Ammonites, then meet the wonderfully tangled Nipponites mirabilis. Research into its buoyancy and balance offers a glimpse of how such an unlikely-looking shell might have worked in the water.

WHAT ARE THOSE LACY PATTERNS?

Some fossils reveal lines that resemble branching rivers or finely cut leaves. These are sutures, marking where the internal walls between chambers met the outer shell wall. They are different from the raised ribs on the outside of the shell.

Those delicate-looking lines trace a three-dimensional structure inside the shell. The chamber walls, called septa, were folded where they joined the outer wall. One long-standing idea is that these folds acted like internal bracing, helping the shell resist the surrounding water pressure, which increases with depth.

But more elaborate lace did not necessarily mean a stronger shell or a deeper-diving ammonite. Mechanical studies have produced mixed results: extra folding can reduce stress in the outer shell wall while increasing stress in the septa themselves. The relationship between sutures, shell strength and living depth remains debated—a beautiful pattern with a scientific mystery still tucked inside. For a closer look at the evidence, see research on ammonite septa and water pressure.

Their patterns vary among ammonites and help palaeontologists distinguish groups. Explore the detail in Sutures, Ridges and Lobes.

HOW CAN AN AMMONITE HELP DATE A ROCK?

Some ammonite species were widespread but existed for comparatively short intervals of geological time. Recognising them can help scientists correlate rock layers in different places and establish their relative ages. This use of fossils is called biostratigraphy.

The fossil does not carry an exact numerical date. Its identity is one piece of evidence considered alongside the surrounding geology. Read more in Ammonite Time Keepers: Index Fossils.

HOW BIG COULD AN AMMONITE GROW?

Ammonites came in an amazing range of sizes. Some were smaller than a coin. Others grew shells wider than a bicycle wheel! A famous giant called Parapuzosia seppenradensis, found in Germany, preserves a shell about 1.74 metres across—roughly the height of an adult. Even that huge fossil is incomplete.

Size alone does not tell us an ammonite’s age. Different species grew to different sizes, and a small fossil might be a youngster or a fully grown member of a small species.

Meet a Canadian giant in The Giant Fossil Ammonite of Fernie. Can you imagine a spiral that big?

WHAT DID AMMONITES EAT—AND WHAT ATE THEM?

Not every ammonite had the same menu. Some ate tiny animals drifting in the water, called plankton. Scientists have found the remains of tiny crustaceans and a baby sea snail near the mouthparts of a fossil Baculites, a straight-shelled ammonite. That is a wonderful clue to an ancient meal!

Other ammonites may have eaten larger prey or scavenged food. Their diets probably varied, and scientists study their jaws and rare food remains to work out what they ate.

Ammonites could become someone else’s dinner, too. Marine reptiles, including some mosasaurs and ichthyosaurs, ate them. Their shells offered protection, but could not keep every hungry hunter away.

Meet one of those ocean hunters in Mosasaur of Vancouver Island, or explore the research into an ammonite’s last meal.

HOW DOES AN AMMONITE BECOME A FOSSIL?

Imagine an empty ammonite shell settling onto the sea floor. Mud or sand buries it. Burial can help protect it from being broken apart, although most shells never become fossils.

Over a very long time, the sediment around the shell can harden into rock. Sometimes parts of the original shell survive. Sometimes minerals replace the shell. In other cases, the shell dissolves but leaves its shape behind. Sediment or minerals filling the inside can form a cast—like a model of the space inside the shell.

Later, erosion can wear away the surrounding rock and reveal the fossil. Some ammonites are preserved inside rounded lumps of cemented sediment called concretions. Discover these natural time capsules in Ammonites in Concretion.

KEEP THE QUESTIONS COMING

Ready for a little fossil detective work? Pick an ammonite photograph, trace its spiral with your finger and sketch what catches your eye. Ribs? Spines? Lacy lines? Gather your clues before giving your fossil a name. Every good mystery begins with a closer look—and one more question!

Have a question you'd like answered? Drop me a message over on Facebook or in the contact form at www.fossilhuntress.com. 

For the permanent FAQ, photographs and a collection of related stories, bookmark Ammonites: A Guide to Ancient Oceans.

NIPPONITES: THE AMMONITE THAT TIED ITSELF IN KNOTS

Nipponites mirabilis photo by Masahiro Miyasaka

Of all the unlikely body plans, Nipponites take the cake! Just look at the twists and turns in these great photos captured by Masahiro Miyasaka. 

Imagine slipping beneath the surface of a Cretaceous sea. Above you, sunlight breaks into shifting ribbons. 

Tiny particles drift through the water, catching the light before disappearing into blue.

For our imagined encounter, we are travelling to the ancient seas of what is now Japan. Somewhere ahead, a small shape comes into view.

At first, it looks like a piece of tangled cord.

Then you notice the ribs along its surface. The looping curves. The extraordinary shell that seems to have doubled back on itself after forgetting where it was going.

Meet Nipponites mirabilis, an ammonite with a shell resembling a ball of wool after a kitten has finished with it.

If you have ever struggled to untangle a necklace, you may feel an immediate connection.

Most of us picture an ammonite as a handsome spiral: a shell curling neatly around itself, each successive whorl following the last. 

An Ammonite Beyond the Familiar Spiral

Nipponites mirabilis photo by Masahiro Miyasaka

Nipponites takes that familiar outline and sends it wandering through three dimensions.

Ammonites were marine molluscs belonging to the cephalopods, the broader group that includes living squid, octopuses, cuttlefish and nautiluses. 

Their chambered shells helped them remain buoyant. The animal occupied the outer living chamber, adding to its shell as it grew.

Some ammonites developed shells that departed dramatically from the familiar flat spiral. These are called heteromorphs. Among them, Nipponites is particularly good at making people stop, lean closer and say, “Surely that cannot be right.”

Yet there it is.

Its shell raises a delicious palaeontological puzzle. How could an animal carrying something so apparently awkward stay balanced in the water?

As you might have guessed, some very good folk decided to try and answer that question. 

Modelling Buoyancy and Balance

In a study published in 2020, David J. Peterman, Tomoyuki Mikami and Shinya Inoue investigated Nipponites mirabilis using digital reconstructions. Their models examined 14 stages of growth, allowing them to explore how the animal’s balance changed as its shell developed.

The results suggested that it could achieve neutral buoyancy throughout each stage. In other words, its shell need not have condemned it to life on the seabed.

N. mirabilis (left); Ainoceras kamuy (right)

The modelling also suggested a fascinating possibility: its unusual form could have helped it turn around a vertical axis. 

The researchers proposed a relatively low-energy lifestyle, slowly rotating while searching for planktonic prey.

Picture that for a moment.

A little living sculpture, suspended in seawater, gently turning as the surrounding ocean carries potential meals within reach, rather like a rolling buffet. Our imagined animal has become rather more graceful.

There is another surprise hidden in those bends. Nipponites began with a more conventional open coil before developing alternating U-shaped turns. Its growth followed a recognisable pattern. The apparent jumble had underlying order.

What Remains Unknown?

Of course, a model cannot show us an actual feeding animal. The proposed pirouetting lifestyle remains an interpretation, and many details of its behaviour are unknown.

That uncertainty is part of the pleasure.

Look again at the fossil. Follow a curve with your eyes. Watch it turn away from you, return and disappear behind another loop. Then imagine water filling the spaces between those bends.

What seemed cumbersome in a display case becomes a question about movement. What looked like a tangle becomes a record of growth.

Fancy reading their paper? You can find more here:

Peterman, D. J., Mikami, T. and Inoue, S. (2020). The balancing act of Nipponites mirabilis (Nostoceratidae, Ammonoidea): Managing hydrostatics throughout a complex ontogeny. PLOS ONE, 15(8), e0235180.

Explore more ammonites in the Fossil Huntress Guide to Ancient Oceans.

Explore more unusual shell forms in Heteromorph Ammonites.

BEAUTIFUL PATHOLOGY: QUENSTEDTOCERAS

What you are seeing here is a protuberance extruding from the venter of Quenstedtoceras cf. leachi (Sowerby). It is a pathology in the shell from hosting immature bivalves that shared the seas with these Middle Jurassic, Upper Callovian, Lamberti zone fauna from the Volga River basin. 

The collecting site is the now inactive Dubki commercial clay quarry and brickyard near Saratov, Russia. 

The site has produced thousands of ammonite specimens. A good 1,100 of those ended up at the Black Hills Institute of Geological Research in Hill City, South Dakota. 

Roughly 1,000 of those are Quenstedtoceras (Lamberticeras) lamberti and the other 100 are a mix of other species found in the same zone. These included Eboraciceras, Peltoceras, Kosmoceras, Grossouvria, Proriceras, Cadoceras and Rursiceras. 

What is especially interesting is the volume of specimens — 167 Quenstedtoceras (Lamberticeras) lamberti and 89 other species in the Black Hills collection — with healed predation injuries. It seems Quenstedtoceras (Lamberticeras) lamberti are the most common specimens found here and so not surprisingly the most common species found injured. 

Of the 1,000, 655 of the Quenstedtoceras (Lamberticeras) lamberti displayed some sort of deformation or growth on the shell or had grown in a tilted manner. 

Again, some of the Q. lamberti had small depressions in the centre likely due to a healed bite and hosting infestations of the immature bivalve Placunopsis and some Ostrea. 

The bivalves thrived on their accommodating hosts and the ammonites carried on, growing their shells right up and over their bivalve guests. 

This relationship led to some weird and deformities of their shells. They grow in, around, up and over nearly every surface of the shell and seem to have lived out their lives there. It must have gotten a bit unworkable for the ammonites, their shells becoming warped and unevenly weighted. 

Over time, both the flourishing bivalves and the ammonite shells growing up and over them produced some of the most interesting pathology specimens I have ever seen.    

In the photo here from Emil Black, you can see some of the distorted shapes of Quenstedtoceras sp. 

Look closely and you see a trochospiral or flattened appearance on one side while they are rounded on the other. 

All of these beauties hail from the Dubki Quarry near Saratov, Russia. The ammonites were collected in marl or clay used in brick making. The clay particles suggest a calm, deep marine environment. 

One of the lovely features of the preservation here is the amount of pyrite filling and replacement. It looks like these ammonites were buried in an oxygen-deficient environment. 

The ammonites were likely living higher in the water column, well above the oxygen-poor bottom. An isotopic study would be interesting to prove this hypothesis. 

There's certainly enough of these ammonites that have been recovered to make that possible. It's estimated that over a thousand specimens have been recovered from the site but that number is likely much higher. But these are not complete specimens. We mostly find the phragmocones and partial body chambers. Given the numbers, this may be a site documenting a mass spawning death over several years or generations.

If you fancy a read on all things cephie, consider picking up a copy of Cephalopods Present and Past: New Insights and Fresh Perspectives edited by Neil Landman and Richard Davis. Figure 16.2 is from page 348 of that publication and shows the hosting predation quite well. 

Photos: Courtesy of the deeply awesome Emil Black. These are in his personal collection that I hope to see in person one day. 

It was his sharing of the top photo and the strange anomaly that had me explore more about the fossils from Dubki and the weird and wonderful hosting relationship between ammonites and bivalves. Thank you, my friend!

BEAUTY IN STONE: ANAHOPLITES PLANUS

There are fossils that whisper and then there are those that positively sing.

This interesting beauty is a splendid specimen of Anahoplites planus (Mantell, 1822), drawn from Albian-aged sediments at Courcelles-sur-Voire in the Aube region of north-central France. 

And sing, it does! There are so many things going on here!

Roughly 105 million years ago, when warm Cretaceous seas spread across much of Europe, this elegant cephalopod cruised ancient waters with all the poise of a creature that knew it wore excellent tailoring.

Anahoplites, first named by Sowerby in 1815, is a delightfully refined genus of hoplitid ammonite. 

Its shell is compressed and neatly streamlined, with flat flanks, a narrow venter — sometimes grooved, sometimes smooth — and graceful, flexuous ribs rising from modest umbilical tubercles before ending in a fringe of fine ventrolateral nodes. In short: less brute force, more couture. 

Its sturdier cousins in the Hoplitinae favour broader whorls and heavier ornament, but Anahoplites has always struck a finer silhouette.

Today, the genus sits comfortably within the subfamily Anahoplitinae, a taxonomic reshuffle that recognises its more delicate build and distinct style. We find these beauties in Middle to Late Albian rocks from England across Europe and eastward toward the Transcaspian reaches near the Caspian Sea — proof that good design travels.

And what a setting this fossil calls home. The Aube department lends its name to the Albian Stage itself, established by d’Orbigny in 1842. 

Here, the stratotype succession includes the Argiles tégulines de Courcelles, some 82 metres of clay-rich deposits, overlain by the Marnes de Brienne, a further 43 metres of marl. Their boundary is marked by a hardened bed, clear in the field to those with sharp eyes and muddy boots.

This particular shell, measuring 113 mm across, did not rest alone on the seafloor. It became a tiny apartment block after death. 

Two forms of bryozoans encrust its surface, joined by an oyster and industrious serpulid worms, all leaving their marks upon those handsome flanks. Even in death, it was prime real estate.

Lovingly prepared using potash by José Juárez Ruiz of Spain, this fossil now offers us not just the form of one ammonite, but a snapshot of an ancient community. 

AMMONITES IN CONCRETION

At first glance they look like ordinary stones—rounded, weathered, unassuming. 

But then you notice the delicious hints: a spiral ghosting through the surface, a faint rib, a seam where time is ready to split wide open—it's magic!

Ammonites, long extinct cephalopods, so often appear this way because, shortly after death, their shells became chemical centres of attraction on the seafloor. 

As the soft tissues decayed, they altered the surrounding sediment, triggering minerals—often calcium carbonate or iron-rich compounds—to precipitate rapidly around the shell. 

This early cementation formed a concretion, a protective stone cocoon that hardened long before the surrounding mud was compressed into rock. While everything around it flattened, cracked, and distorted under pressure, the ammonite inside remained cradled and whole.

What you see here is a gathering of these time capsules: a cluster of ammonites preserved in their concretions, each one split or weathered just enough to reveal the coiled story within. 

Some are neatly halved, spirals laid bare like fingerprints from ages past; others are only just beginning to show themselves, teasing their presence beneath rough stone skins. 

Together, they tell a familiar fossil-hunter’s tale—of patience, sharp eyes, and the thrill of knowing that this unassuming rock holds an ancient ocean inside.

BEAUTIFUL PATHOLOGY: QUENSTEDTOCERAS

What you are seeing here is a protuberance extruding from the venter of Quenstedtoceras cf. leachi (Sowerby). It is a pathology in the shell from hosting immature bivalves that shared the seas with these Middle Jurassic, Upper Callovian, Lamberti zone fauna from the Volga River basin. 

The collecting site is the now inactive Dubki commercial clay quarry and brickyard near Saratov, Russia. 

The site has produced thousands of ammonite specimens. A good 1,100 of those ended up at the Black Hills Institute of Geological Research in Hill City, South Dakota. 

Roughly 1,000 of those are Quenstedtoceras (Lamberticeras) lamberti and the other 100 are a mix of other species found in the same zone. These included Eboraciceras, Peltoceras, Kosmoceras, Grossouvria, Proriceras, Cadoceras and Rursiceras. 

What is especially interesting is the volume of specimens — 167 Quenstedtoceras (Lamberticeras) lamberti and 89 other species in the Black Hills collection — with healed predation injuries. It seems Quenstedtoceras (Lamberticeras) lamberti are the most common specimens found here and so not surprisingly the most common species found injured. 

Of the 1,000, 655 of the Quenstedtoceras (Lamberticeras) lamberti displayed some sort of deformation or growth on the shell or had grown in a tilted manner. 

Again, some of the Q. lamberti had small depressions in the centre likely due to a healed bite and hosting infestations of the immature bivalve Placunopsis and some Ostrea. 

The bivalves thrived on their accommodating hosts and the ammonites carried on, growing their shells right up and over their bivalve guests. 

This relationship led to some weird and deformities of their shells. They grow in, around, up and over nearly every surface of the shell and seem to have lived out their lives there. It must have gotten a bit unworkable for the ammonites, their shells becoming warped and unevenly weighted. 

Over time, both the flourishing bivalves and the ammonite shells growing up and over them produced some of the most interesting pathology specimens I have ever seen.    

In the photo here from Emil Black, you can see some of the distorted shapes of Quenstedtoceras sp. 

Look closely and you see a trochospiral or flattened appearance on one side while they are rounded on the other. 

All of these beauties hail from the Dubki Quarry near Saratov, Russia. The ammonites were collected in marl or clay used in brick making. The clay particles suggest a calm, deep marine environment. 

One of the lovely features of the preservation here is the amount of pyrite filling and replacement. It looks like these ammonites were buried in an oxygen-deficient environment. 

The ammonites were likely living higher in the water column, well above the oxygen-poor bottom. An isotopic study would be interesting to prove this hypothesis. 

There's certainly enough of these ammonites that have been recovered to make that possible. It's estimated that over a thousand specimens have been recovered from the site but that number is likely much higher. But these are not complete specimens. We mostly find the phragmocones and partial body chambers. Given the numbers, this may be a site documenting a mass spawning death over several years or generations.

If you fancy a read on all things cephie, consider picking up a copy of Cephalopods Present and Past: New Insights and Fresh Perspectives edited by Neil Landman and Richard Davis. Figure 16.2 is from page 348 of that publication and shows the hosting predation quite well. 

Photos: Courtesy of the deeply awesome Emil Black. These are in his personal collection that I hope to see in person one day. 

It was his sharing of the top photo and the strange anomaly that had me explore more about the fossils from Dubki and the weird and wonderful hosting relationship between ammonites and bivalves. Thank you, my friend!

EPIC FOSSIL HUNTING: TYAUGHTON & CASTLE PEAK

Some places stay with you long after you've left them.

Tyaughton, north of Gold Bridge beneath the rugged skyline of Castle Peak, is one of those places for me. 

It is wild, breathtaking country where glaciers cling to the mountains, marmots whistle from rocky slopes, golden eagles drift effortlessly overhead, and every winding trail feels like it leads into another chapter of Earth's history.

It is also one of British Columbia's most remarkable places to hunt Triassic and Jurassic fossils.

Standing among these peaks, it is almost impossible to picture that some 200 to 220 million years ago this entire landscape lay beneath a warm tropical sea. Instead of alpine meadows and mountain goats, graceful ammonites cruised the water column while crinoids swayed gently on the seafloor. 

Brachiopods, bivalves, gastropods and countless other marine creatures flourished in an ocean that has long since disappeared.

Those ancient seabeds would one day be lifted thousands of metres skyward as the Coast Mountains rose around them, preserving their story within layers of limestone and shale.

Badouxia ammonites

There is nothing quite like splitting open a weathered slab and finding a beautifully preserved ammonite waiting inside. 

One careful tap with the rock hammer and suddenly you are sharing a moment with an animal that last saw daylight before the first dinosaurs truly came into their own. 

Those discoveries never lose their magic.

The nearby Taseko Lakes region has yielded one of the finest collections of Late Hettangian ammonites ever discovered in British Columbia. 

Over many remarkable field seasons, we documented thirty-five ammonite taxa and described three entirely new species, greatly expanding our understanding of Early Jurassic life along the ancient western margin of North America.

That work holds a particularly special place in my heart.

I had the enormous honour of having one of those new species named after me by Dr. Louise Longridge of the University of British Columbia. Fergusonites hendersonae is a beautiful little nektonic carnivorous ammonite that now carries my family name through the scientific literature. It remains one of the greatest honours of my life.

I first met Louise as an undergraduate, and later had the privilege of joining expeditions into the Taseko backcountry alongside wonderful friends from the Vancouver Island Paleontological Society, the Vancouver Paleontological Society, and researchers from UBC. 

We followed in the footsteps of the legendary Dr. Howard Tipper, whose meticulous geological mapping and extraordinary knowledge of Jurassic ammonites transformed our understanding of this part of British Columbia. His maps remain the foundation for much of the work we continue today.

Those expeditions were unforgettable.

Over several field seasons we endured altitude sickness, rain, snow, grizzly bears, and more than a few freezing nights camped beside glaciers. Helicopters spared us days of hiking into some of the most inaccessible fossil localities in the province, where every outcrop held the possibility of something extraordinary. 

Along with the three new ammonite species, we recovered beautifully preserved gastropods, crustaceans, and countless specimens that continue to help us piece together the history of these ancient seas.

What makes these fossils so important is not simply their beauty.

Ammonites evolved rapidly, making them some of our finest index fossils. By comparing species found here with those from Nevada, Alaska, South America, New Zealand, and Europe, we can correlate rock layers across continents and refine the geological timescale for the Early Jurassic. 

These tiny coiled shells have become some of our most powerful tools for understanding how life recovered following the greatest mass extinction our planet has ever known.

Collecting in this country also comes with responsibility. Many of these fossil localities lie within sensitive alpine environments or protected areas where collecting requires permits or is prohibited altogether. We tread lightly, respect the land, follow regulations, and remember that we are visitors in landscapes that have preserved these stories for hundreds of millions of years.

That is perhaps what I love most. You stand surrounded by towering peaks, yet beneath your boots lies the floor of an ancient tropical ocean. The mountains themselves are built from forgotten seas, and every fossil reminds us that Earth is never still. 

Continents wander. Oceans open and close. Mountains rise. Species flourish, disappear, and give way to those yet to come.

FERNIE, BRITISH COLUMBIA: FOSSIL AMMONITE AS LARGE AS A SMART CAR

Titanites occidentalis, Fernie Ammonite

The Fernie ammonite—long known as Titanites occidentalis—has officially been given a new name: Corbinites occidentalis, a fresh genus erected after a meticulous re-evaluation of this Western Giant’s anatomy and lineage. 

What hasn’t changed is its breathtaking presence high on Coal Mountain near Fernie, British Columbia, where this colossal cephalopod has rested for roughly 150 million years.

This extraordinary fossil belongs to the family Lithacoceratinae within the ataxioceratid ammonites. 

Once thought to be a close cousin of the great Titanites of Dorset, new material—including two additional large specimens discovered at nearby mine sites—reveals ribbing patterns and growth-stage features that simply didn’t match Titanites. 

With these multiple overlapping growth stages finally available, paleontologists had the missing pieces needed to correct its identity.

So, Titanites occidentalis no more—meet Corbinites occidentalis, a giant ammonite likely endemic to the relatively isolated early Alberta foreland basin of the Late Jurassic.

Fernie, British Columbia, Canada

The Fernie ammonite is a carnivorous cephalopod from the latest Jurassic (Tithonian). 

The spectacular individual on Coal Mountain measures 1.4 metres across—about the size of a small car tire and absolutely staggering when you first see it hugged by the mountainside.

The first specimen, discovered in 1947 by a British Columbia Geophysical Society mapping team at Coal Creek, was initially mistaken for a “fossil truck tire.” 

Fair enough—if a truck tire had been forged in the Jurassic and left on a mountaintop. It was later described by GSC paleontologist Hans Frebold, who gave it the name Titanites occidentalis, inspired by the giant ammonites of Dorset. 

For decades, that name stuck, even though paleontologists suspected the attribution was shaky due to poor preservation of the holotype’s inner whorls.

Recent discoveries of two additional specimens at Teck Resources’ Coal Mountain Mine finally provided the evidence needed for reassessment. 

With intact inner whorls and beautifully preserved ribbing—including hallmark variocostate and ataxioceratoid ornamentation—researchers Terence P. Poulton and colleagues demonstrated that the Canadian ammonite does not belong in Titanites. 

Their work (Volumina Jurassica, 2023) established Corbinites as a brand-new genus, with C. occidentalis as its type and only known species.

These specimens—one exceeding a metre, another about 64 cm—confirm a resident ammonite population within this basin. And as of now, these giants are unique to Western Canada.

A Journey Up Coal Mountain

If you’re keen to meet Corbinites occidentalis in the wild, you’ll want to head to Fernie, in southeastern British Columbia, close to the Alberta border. 

As your feet move up the hillside, you can imagine this land 10,000 years ago, rising above great glaciers. Where footfalls trace the steps of those that came before you. This land has been home to the Yaq̓it ʔa·knuqⱡi ‘it First Nation and Ktunaxa or Kukin ʔamakis First Nations whose oral history have them living here since time immemorial. Like them, take only what you need and no more than the land offers — packing out anything that you packed in. 

Active logging in the area since 2021 means that older directions are now unreliable—trailheads have shifted, and a fair bit of bushwhacking is the price of admission. Though clear-cutting reshaped the slope, loggers at CanWel showed admirable restraint: they worked around the fossil, leaving it untouched.

The non-profit Wildsight has been championing efforts to protect the ammonite, hoping to establish an educational trail with provincial support and possible inclusion under the Heritage Conservation Act—where the fossil’s stewardship could be formally recognised.

HIKING TO THE FERNIE AMMONITE (IMPORTANT UPDATE: TRAIL CLOSED)

From the town of Fernie, British Columbia, you would traditionally head east along Coal Creek Road toward Coal Creek, with the ammonite site sitting 3.81 km from the road’s base as the crow flies. 

The classic approach begins at a roadside exposure of dark grey to black Cretaceous plant fossils, followed by a creek crossing and a steep, bushwhacking ascent.

However — and this is critical — the trail is currently closed.

The entire access route runs straight through an area of active logging, and conditions on the slope are extremely dangerous. Between heavy equipment, unstable cutblocks, and altered drainages, this is not a safe place for hikers right now.

Conservation groups, including Wildsight, continue working toward restoring safe public access and formalising the site under the Heritage Conservation Act. 

Their long-term goal is to reopen the trail as a designated educational hike with proper signage, but at present, the route should not be attempted. 

Once logging operations move out of the area and safety assessments are done, the possibility of reopening may return.

For now, the safest—and strongly recommended—way to view this iconic fossil is via the excellent cast on display at the Courtenay & District Museum on Vancouver Island, or at the Visitor Information Centre in Sparwood.

Photo credit: Vince Mo Media. Vince is an awesome photographer and drone operator based in Fernie, BC. Check out his work (and hire him!) by visiting his website at vmmedia.ca.

OIL IN WATER BEAUTY: FOSSILS OF FOLKSTONE

Sheer beauty — a beautiful Euhoplites ammonite from Folkstone, UK. I've been really enjoying looking at all oil-in-water colouring and chunkiness of these ammonites.

Euhoplites is an extinct ammonoid cephalopod from the Lower Cretaceous, characterized by strongly ribbed, more or less evolute, compressed to inflated shells with flat or concave ribs, typically with a deep narrow groove running down the middle.

In some, ribs seem to zigzag between umbilical tubercles and parallel ventrolateral clavi. In others, the ribs are flexious and curve forward from the umbilical shoulder and lap onto either side of the venter.

Its shell is covered in the lovely lumps and bumps we associate with the genus. The function of these adornments are unknown. I wonder if they gave them greater strength to go deeper into the ocean to hunt for food. 

They look to have been a source of hydrodynamic drag, likely preventing Euhoplites from swimming at speed. Studying them may give some insight into the lifestyle of this ancient marine predator. Euhoplites had shells ranging in size up to a 5-6cm. 

We find them in Lower Cretaceous, middle to upper Albian age strata. Euhoplites has been found in Middle and Upper Albian beds in France where it is associated respectively with Hoplites and Anahoplites, and Pleurohoplites, Puzosia, and Desmoceras; in the Middle Albian of Brazil with Anahoplites and Turrilites; and in the Cenomanian of Texas.

This species is the most common ammonite from the Folkstone Fossil Beds in southeastern England where a variety of species are found, including this 37mm beauty from the collections of José Juárez Ruiz.

PSEUDOTHURMANNIA: CRETACEOUS AMMONITE

Meet Pseudothurmannia — one of those marvellous Cretaceous ammonites that looks as though nature spent extra time on the details. 

This extinct cephalopod belongs to the subclass Ammonoidea and is tucked neatly within the family Crioceratitidae, part of the wonderfully curly branch of ammonites known as the Ancylocerataceae. 

A proper pedigree, if ever there was one.

Now, have a look at those shell lines — the intricate, looping seams known as sutures. These are no random squiggles. 

They are the biological fingerprints of ammonites, each species carrying its own signature pattern. To the trained eye, they tell time as neatly as any watchmaker. 

Compare the sutures of this beauty with its kin, and we know Pseudothurmannia cruised ancient seas during the Early Cretaceous, from the Hauterivian through to the Barremian, some 132 to 125 million years ago.

Like its modern cousins — squid, cuttlefish and octopus — this fellow was no passive floater. Hidden within that elegant shell was a sharp, beak-like jaw surrounded by a ring of grasping tentacles. Those arms were built for business, used to seize prey from the water column: plankton, small fish, crustaceans and whatever else wandered too close.

And catching a fish while swimming is no easy business. Try it yourself and report back. Ammonites, however, were masters of the ambush — swift, buoyant, and gloriously well-equipped for life in the open sea. 

For millions of years, they were among the great success stories of the oceans… until, of course, the curtain came down at the end of the Cretaceous.

Within their shells, they had a number of chambers, called septa, filled with gas or fluid that were interconnected by a wee air tube. By pushing air in or out, they were able to control their buoyancy in the water column. 

They lived in the last chamber of their shells, continuously building new shell material as they grew. As each new chamber was added, the squid-like body of the ammonite would move down to occupy the final outside chamber.

Shells of Pseudothurmannia can reach a diameter of about 4–12 centimetres (1.6–4.7 in). They show flat or slightly convex sides, with dense ribs and a subquadrate whorl section.

We find fossils of Pseudothurmannia in Cretaceous outcrops in Antarctica, Czechoslovakia, France, Hungary, Italy, Japan, Morocco, Spain, Russia and the United States. The specimen you see here is in the collection of the deeply awesome Manuel Peña Nieto from Córdoba, Spain and is from the Lower Cretaceous of Mallorca.

BE STILL MY HEART: ANAHOPLITES PLANUS

There are fossils that whisper and then there are those that positively sing.

This interesting beauty is a splendid specimen of Anahoplites planus (Mantell, 1822), drawn from Albian-aged sediments at Courcelles-sur-Voire in the Aube region of north-central France. 

And sing, it does! There are so many things going on here!

Roughly 105 million years ago, when warm Cretaceous seas spread across much of Europe, this elegant cephalopod cruised ancient waters with all the poise of a creature that knew it wore excellent tailoring.

Anahoplites, first named by Sowerby in 1815, is a delightfully refined genus of hoplitid ammonite. 

Its shell is compressed and neatly streamlined, with flat flanks, a narrow venter — sometimes grooved, sometimes smooth — and graceful, flexuous ribs rising from modest umbilical tubercles before ending in a fringe of fine ventrolateral nodes. In short: less brute force, more couture. 

Its sturdier cousins in the Hoplitinae favour broader whorls and heavier ornament, but Anahoplites has always struck a finer silhouette.

Today, the genus sits comfortably within the subfamily Anahoplitinae, a taxonomic reshuffle that recognises its more delicate build and distinct style. We find these beauties in Middle to Late Albian rocks from England across Europe and eastward toward the Transcaspian reaches near the Caspian Sea — proof that good design travels.

And what a setting this fossil calls home. The Aube department lends its name to the Albian Stage itself, established by d’Orbigny in 1842. 

Here, the stratotype succession includes the Argiles tégulines de Courcelles, some 82 metres of clay-rich deposits, overlain by the Marnes de Brienne, a further 43 metres of marl. Their boundary is marked by a hardened bed, clear in the field to those with sharp eyes and muddy boots.

This particular shell, measuring 113 mm across, did not rest alone on the seafloor. It became a tiny apartment block after death. 

Two forms of bryozoans encrust its surface, joined by an oyster and industrious serpulid worms, all leaving their marks upon those handsome flanks. Even in death, it was prime real estate.

Lovingly prepared using potash by José Juárez Ruiz of Spain, this fossil now offers us not just the form of one ammonite, but a snapshot of an ancient community. 

One shell. Many stories. And my, what a beauty.

FOSSIL HUNTRESS PALEONTOLOGY PODCAST

Step into deep time with The Fossil Huntress Podcast—a journey through the ancient heartbeat of our planet.

Close your eyes and imagine the world as it once was: strange seas teeming with ammonites and trilobites, ichthyosaurs and mosasaurs, fern-filled forests echoing with the footsteps of dinosaurs, and sun-warmed badlands whispering secrets from ages long past.

Together, we’ll explore Earth’s great fossil treasures—places where time slows and stone remembers. From sacred landscapes to world-famous dig sites, each episode unearths the science and stories that connect us to all who have ever lived, swum, or flown across this incredible planet.

This is a podcast about discovery, deep history, and the wonder of life itself. I'll share what you want to bring with you to enjoy your time in the field and adventure stories from my time there. 

From the tiniest single-celled ancestors to the mighty creatures that once ruled the Earth, you’ll hear how fossils tell the tale of change, resilience, and renewal—the discoveries that had me whoop with joy and the crushing defeat of a poorly split piece of shale.

So grab your curiosity, favourite the show, and come fossil-hunting through time with me—one ancient adventure at a time for some family-friendly fun. 

Head on over to the Fossil Huntress Podcast on Spotify, Apple or your favourite streaming service. The latest episode answers the question, "What Killed the Dinosaurs?" Currently streaming in 116 countries. 

SAKARA MADAGASGAR: OXFORDIAN OUTCROPS

Lobolytoceras costellatum

This big beastie is a superb specimen of the ammonite Lobolytoceras costellatum showing the intricate fractal pattern of its septa. 

This lovely measures to a whopping 230 mm and hails from Oxfordian outcrops near Sakara, Madagascar. Lovingly prepped by the supremely talented José Juárez Ruiz.

Ammonites were predatory, squidlike creatures that lived inside coil-shaped shells. 

Like other cephalopods, ammonites had sharp, beak-like jaws inside a ring of squid-like tentacles that extended from their shells. They used these tentacles to snare prey — plankton, vegetation, fish and crustaceans — similar to the way a squid or octopus hunt today.

Catching a fish with your hands is no easy feat, as I'm sure you know. Ammonites did the equivalent, catching prey in their tentacles. They were skilled and successful hunters. They caught their prey while swimming and floating in the water column. 

Within their shells, they had a number of chambers, called septa, filled with gas or fluid that were interconnected by a wee air tube. By pushing air in or out, they were able to control their buoyancy in the water column.

They lived in the last chamber of their shells, continuously building new shell material as they grew. As each new chamber was added, the squid-like body of the ammonite would move down to occupy the final outside chamber.

They were a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids — octopuses, squid, and cuttlefish) then they are to shelled nautiloids such as the living Nautilus species.

Lobolytoceras costellatum

Ammonites have intricate and complex patterns on their shells called sutures. The suture patterns differ across species and tell us what time period the ammonite is from. 

If they are geometric with numerous undivided lobes and saddles and eight lobes around the conch, we refer to their pattern as goniatitic, a characteristic of Paleozoic ammonites.

Ammonites first appeared about 240 million years ago, though they descended from straight-shelled cephalopods called bacrites that date back to the Devonian, about 415 million years ago, and the last species vanished in the Cretaceous–Paleogene extinction event.

They were prolific breeders that evolved rapidly. If you could cast a fishing line into our ancient seas, it is likely that you would hook an ammonite, not a fish. 

They were prolific back in the day, living (and sometimes dying) in schools in oceans around the globe. We find ammonite fossils (and plenty of them) in sedimentary rock from all over the world.

In some cases, we find rock beds where we can see evidence of a new species that evolved, lived and died out in such a short time span that we can walk through time, following the course of evolution using ammonites as a window into the past.

For this reason, they make excellent index fossils. An index fossil is a species that allows us to link a particular rock formation, layered in time with a particular species or genus found there. 

Generally, deeper is older, so we use the sedimentary layers rock to match up to specific geologic time periods, rather the way we use tree-rings to date trees. A handy way to compare fossils and date strata across the globe.

Explore more ammonites in the Fossil Huntress Guide to Ancient Oceans.

A MASSIVE AMMONITE THE SIZE OF A CAR: THE FERNIE AMMONITE

Titanites occidentalis, Fernie Ammonite

The Fernie ammonite—long known as Titanites occidentalis—has officially been given a new name: Corbinites occidentalis, a fresh genus erected after a meticulous re-evaluation of this Western Giant’s anatomy and lineage. 

What hasn’t changed is its breathtaking presence high on Coal Mountain near Fernie, British Columbia, where this colossal cephalopod has rested for roughly 150 million years.

This extraordinary fossil belongs to the family Lithacoceratinae within the ataxioceratid ammonites. 

Once thought to be a close cousin of the great Titanites of Dorset, new material—including two additional large specimens discovered at nearby mine sites—reveals ribbing patterns and growth-stage features that simply didn’t match Titanites. 

With these multiple overlapping growth stages finally available, paleontologists had the missing pieces needed to correct its identity.

So, Titanites occidentalis no more—meet Corbinites occidentalis, a giant ammonite likely endemic to the relatively isolated early Alberta foreland basin of the Late Jurassic.

Fernie, British Columbia, Canada

The Fernie ammonite is a carnivorous cephalopod from the latest Jurassic (Tithonian). 

The spectacular individual on Coal Mountain measures 1.4 metres across—about the size of a small car tire and absolutely staggering when you first see it hugged by the mountainside.

The first specimen, discovered in 1947 by a British Columbia Geophysical Society mapping team at Coal Creek, was initially mistaken for a “fossil truck tire.” 

Fair enough—if a truck tire had been forged in the Jurassic and left on a mountaintop. It was later described by GSC paleontologist Hans Frebold, who gave it the name Titanites occidentalis, inspired by the giant ammonites of Dorset. 

For decades, that name stuck, even though paleontologists suspected the attribution was shaky due to poor preservation of the holotype’s inner whorls.

Recent discoveries of two additional specimens at Teck Resources’ Coal Mountain Mine finally provided the evidence needed for reassessment. 

With intact inner whorls and beautifully preserved ribbing—including hallmark variocostate and ataxioceratoid ornamentation—researchers Terence P. Poulton and colleagues demonstrated that the Canadian ammonite does not belong in Titanites. 

Their work (Volumina Jurassica, 2023) established Corbinites as a brand-new genus, with C. occidentalis as its type and only known species.

These specimens—one exceeding a metre, another about 64 cm—confirm a resident ammonite population within this basin. And as of now, these giants are unique to Western Canada.

A Journey Up Coal Mountain

If you’re keen to meet Corbinites occidentalis in the wild, you’ll want to head to Fernie, in southeastern British Columbia, close to the Alberta border. 

As your feet move up the hillside, you can imagine this land 10,000 years ago, rising above great glaciers. Where footfalls trace the steps of those that came before you. This land has been home to the Yaq̓it ʔa·knuqⱡi ‘it First Nation and Ktunaxa or Kukin ʔamakis First Nations whose oral history have them living here since time immemorial. Like them, take only what you need and no more than the land offers — packing out anything that you packed in. 

Active logging in the area since 2021 means that older directions are now unreliable—trailheads have shifted, and a fair bit of bushwhacking is the price of admission. Though clear-cutting reshaped the slope, loggers at CanWel showed admirable restraint: they worked around the fossil, leaving it untouched.

The non-profit Wildsight has been championing efforts to protect the ammonite, hoping to establish an educational trail with provincial support and possible inclusion under the Heritage Conservation Act—where the fossil’s stewardship could be formally recognised.

HIKING TO THE FERNIE AMMONITE (IMPORTANT UPDATE: TRAIL CLOSED)

From the town of Fernie, British Columbia, you would traditionally head east along Coal Creek Road toward Coal Creek, with the ammonite site sitting 3.81 km from the road’s base as the crow flies. 

The classic approach begins at a roadside exposure of dark grey to black Cretaceous plant fossils, followed by a creek crossing and a steep, bushwhacking ascent.

However — and this is critical — the trail is currently closed.

The entire access route runs straight through an area of active logging, and conditions on the slope are extremely dangerous. Between heavy equipment, unstable cutblocks, and altered drainages, this is not a safe place for hikers right now.

Conservation groups, including Wildsight, continue working toward restoring safe public access and formalising the site under the Heritage Conservation Act. 

Their long-term goal is to reopen the trail as a designated educational hike with proper signage, but at present, the route should not be attempted. 

Once logging operations move out of the area and safety assessments are done, the possibility of reopening may return.

For now, the safest—and strongly recommended—way to view this iconic fossil is via the excellent cast on display at the Courtenay & District Museum on Vancouver Island, or at the Visitor Information Centre in Sparwood.

Photo credit: Vince Mo Media. Vince is an awesome photographer and drone operator based in Fernie, BC. Check out his work (and hire him!) by visiting his website at vmmedia.ca.

SPIRALING BEAUTY: AMMONITES AS INDEX FOSSILS

Argonauticeras besairei, Collection of José Juárez Ruiz.

An exceptional example of fractal building of an ammonite septum, in this clytoceratid Argonauticeras besairei from the awesome José Juárez Ruiz.

Ammonites were predatory, squid-like creatures that lived inside coil-shaped shells.

Like other cephalopods, ammonites had sharp, beak-like jaws inside a ring of squid-like tentacles that extended from their shells. 

They used these tentacles to snare prey, — plankton, vegetation, fish and crustaceans — similar to the way a squid or octopus hunt today.

Catching a fish with your hands is no easy feat, as I'm sure you know. But the Ammonites were skilled and successful hunters. 

They caught their prey while swimming and floating in the water column. Within their shells, they had a number of chambers, called septa, filled with gas or fluid that were interconnected by a wee air tube. By pushing air in or out, they were able to control their buoyancy in the water column.

They lived in the last chamber of their shells, continuously building new shell material as they grew. As each new chamber was added, the squid-like body of the ammonite would move down to occupy the final outside chamber.

They were a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. 

These molluscs, commonly referred to as ammonites, are more closely related to living coleoids — octopuses, squid, and cuttlefish) than they are to shelled nautiloids such as the living Nautilus species.

The Ammonoidea can be divided into six orders:

• Agoniatitida, Lower Devonian - Middle Devonian
• Clymeniida, Upper Devonian
• Goniatitida, Middle Devonian - Upper Permian
• Prolecanitida, Upper Devonian - Upper Triassic
• Ceratitida, Upper Permian - Upper Triassic
• Ammonitida, Lower Jurassic - Upper Cretaceous

Ammonites have intricate and complex patterns on their shells called sutures. The suture patterns differ across species and tell us what time period the ammonite is from. 

If they are geometric with numerous undivided lobes and saddles and eight lobes around the conch, we refer to their pattern as goniatitic, a characteristic of Paleozoic ammonites.

If they are ceratitic with lobes that have subdivided tips; giving them a saw-toothed appearance and rounded undivided saddles, they are likely Triassic. For some lovely Triassic ammonites, take a look at the specimens that come out of Hallstatt, Austria and from the outcrops in the Humboldt Mountains of Nevada.

Hoplites bennettiana (Sowby, 1826).

If they have lobes and saddles that are fluted, with rounded subdivisions instead of saw-toothed, they are likely Jurassic or Cretaceous. 

If you'd like to see a particularly beautiful Lower Jurassic ammonite, take a peek at Apodoceras. Wonderful ridging in that species.

One of my favourite Cretaceous ammonites is the ammonite, Hoplites bennettiana (Sowby, 1826). This beauty is from Albian deposits near Carrière de Courcelles, Villemoyenne, near la région de Troyes (Aube) Champagne in northeastern France.

At the time that this fellow was swimming in our oceans, ankylosaurs were strolling about Mongolia and stomping through the foliage in Utah, Kansas and Texas. 

Bony fish were swimming over what would become the strata making up Canada, the Czech Republic and Australia. Cartilaginous fish were prowling the western interior seaway of North America and a strange extinct herbivorous mammal, Eobaatar, was snuffling through Mongolia, Spain and England.

In some classifications, these are left as suborders, included in only three orders: Goniatitida, Ceratitida, and Ammonitida. Once you get to know them, ammonites in their various shapes and suturing patterns make it much easier to date an ammonite and the rock formation where is was found at a glance.

Ammonites first appeared about 240 million years ago, though they descended from straight-shelled cephalopods called bacrites that date back to the Devonian, about 415 million years ago, and the last species vanished in the Cretaceous–Paleogene extinction event.

They were prolific breeders that evolved rapidly. If you could cast a fishing line into our ancient seas, it is likely that you would hook an ammonite, not a fish. 

They were prolific back in the day, living (and sometimes dying) in schools in oceans around the globe. We find ammonite fossils (and plenty of them) in sedimentary rock from all over the world.

In some cases, we find rock beds where we can see evidence of a new species that evolved, lived and died out in such a short time span that we can walk through time, following the course of evolution using ammonites as a window into the past.

For this reason, they make excellent index fossils. An index fossil is a species that allows us to link a particular rock formation, layered in time with a particular species or genus found there. Generally, deeper is older, so we use the sedimentary layers rock to match up to specific geologic time periods, rather the way we use tree-rings to date trees. A handy way to compare fossils and date strata across the globe.

References: Inoue, S., Kondo, S. Suture pattern formation in ammonites and the unknown rear mantle structure. Sci Rep 6, 33689 (2016). https://doi.org/10.1038/srep33689
https://www.nature.com/articles/srep33689?fbclid=IwAR1BhBrDqhv8LDjqF60EXdfLR7wPE4zDivwGORTUEgCd2GghD5W7KOfg6Co#citeas

Photo: Hoplites Bennettiana from near Troyes, France. Collection de Christophe Marot

Explore more ammonites in the Fossil Huntress Guide to Ancient Oceans.

BACK IN THE USSR: KEPPLERITES

This glorious chocolate block contains the creamy grey ammonite Kepplerites gowerianus (Sowerby 1827) with a few invertebrate friends, including two brachiopods: Ivanoviella sp., Zeilleria sp. and the deep brown gastropod Bathrotomaria sp. 

There is also a wee bit of petrified wood on the backside.

These beauties hail from Jurassic, Lower Callovian outcrops in the Quarry of Kursk Magnetic Anomaly (51.25361,37.66944), Kursk region, Russia. Diameter ammonite 70мм. 

In the mid-1980s, during the expansion and development of one of the quarries, an unusual geological formation was found. This area had been part of the seafloor around an ancient island surrounded by Jurassic Seas. 

The outcrops of this geological formation turned out to be very rich in marine fossil fauna. This ammonite block was found there years ago by the deeply awesome Emil Black. 

In more recent years, the site has been closed to fossil collecting and is in use solely for the processing and extraction of iron ore deposits. Kursk Oblast is one of Russia's major producers of iron ore. The area of the Kursk Magnetic Anomaly has one of the richest iron-ore deposits in the world. Rare Earth minerals and base metals also occur in commercial quantities in several locations. Refractory loam, mineral sands, and chalk are quarried and processed in the region. 

The Kursk Magnetic Anomaly Quarry is not far from the Sekmenevsk Formation or Sekmenevska Svita in Russian, a Cretaceous (Albian to Cenomanian) terrestrial geologic formation where Pterosaur fossils have been found in the sandstones. 

OIL IN WATER BEAUTY: FOSSILS OF FOLKSTONE

Sheer beauty — a beautiful Euhoplites ammonite from Folkstone, UK. I've been really enjoying looking at all oil-in-water colouring and chunkiness of these ammonites.

Euhoplites is an extinct ammonoid cephalopod from the Lower Cretaceous, characterized by strongly ribbed, more or less evolute, compressed to inflated shells with flat or concave ribs, typically with a deep narrow groove running down the middle.

In some, ribs seem to zigzag between umbilical tubercles and parallel ventrolateral clavi. In others, the ribs are flexious and curve forward from the umbilical shoulder and lap onto either side of the venter.

Its shell is covered in the lovely lumps and bumps we associate with the genus. The function of these adornments are unknown. I wonder if they gave them greater strength to go deeper into the ocean to hunt for food. 

They look to have been a source of hydrodynamic drag, likely preventing Euhoplites from swimming at speed. Studying them may give some insight into the lifestyle of this ancient marine predator. Euhoplites had shells ranging in size up to a 5-6cm. 

We find them in Lower Cretaceous, middle to upper Albian age strata. Euhoplites has been found in Middle and Upper Albian beds in France where it is associated respectively with Hoplites and Anahoplites, and Pleurohoplites, Puzosia, and Desmoceras; in the Middle Albian of Brazil with Anahoplites and Turrilites; and in the Cenomanian of Texas.

This species is the most common ammonite from the Folkstone Fossil Beds in southeastern England where a variety of species are found, including this 37mm beauty from the collections of José Juárez Ruiz.

QUENSTEDTOCERAS WITH PATHOLOGY

What you are seeing here is a protuberance extruding from the venter of Quenstedtoceras cf. leachi (Sowerby). It is a pathology in the shell from hosting immature bivalves that shared the seas with these Middle Jurassic, Upper Callovian, Lamberti zone fauna from the Volga River basin. 

The collecting site is the now inactive Dubki commercial clay quarry and brickyard near Saratov, Russia. 

The site has produced thousands of ammonite specimens. A good 1,100 of those ended up at the Black Hills Institute of Geological Research in Hill City, South Dakota. 

Roughly 1,000 of those are Quenstedtoceras (Lamberticeras) lamberti and the other 100 are a mix of other species found in the same zone. These included Eboraciceras, Peltoceras, Kosmoceras, Grossouvria, Proriceras, Cadoceras and Rursiceras. 

What is especially interesting is the volume of specimens — 167 Quenstedtoceras (Lamberticeras) lamberti and 89 other species in the Black Hills collection — with healed predation injuries. It seems Quenstedtoceras (Lamberticeras) lamberti are the most common specimens found here and so not surprisingly the most common species found injured. 

Of the 1,000, 655 of the Quenstedtoceras (Lamberticeras) lamberti displayed some sort of deformation or growth on the shell or had grown in a tilted manner. 

Again, some of the Q. lamberti had small depressions in the centre likely due to a healed bite and hosting infestations of the immature bivalve Placunopsis and some Ostrea. 

The bivalves thrived on their accommodating hosts and the ammonites carried on, growing their shells right up and over their bivalve guests. 

This relationship led to some weird and deformities of their shells. They grow in, around, up and over nearly every surface of the shell and seem to have lived out their lives there. It must have gotten a bit unworkable for the ammonites, their shells becoming warped and unevenly weighted. 

Over time, both the flourishing bivalves and the ammonite shells growing up and over them produced some of the most interesting pathology specimens I have ever seen.    

In the photo here from Emil Black, you can see some of the distorted shapes of Quenstedtoceras sp. 

Look closely and you see a trochospiral or flattened appearance on one side while they are rounded on the other. 

All of these beauties hail from the Dubki Quarry near Saratov, Russia. The ammonites were collected in marl or clay used in brick making. The clay particles suggest a calm, deep marine environment. 

One of the lovely features of the preservation here is the amount of pyrite filling and replacement. It looks like these ammonites were buried in an oxygen-deficient environment. 

The ammonites were likely living higher in the water column, well above the oxygen-poor bottom. An isotopic study would be interesting to prove this hypothesis. 

There's certainly enough of these ammonites that have been recovered to make that possible. It's estimated that over a thousand specimens have been recovered from the site but that number is likely much higher. But these are not complete specimens. We mostly find the phragmocones and partial body chambers. Given the numbers, this may be a site documenting a mass spawning death over several years or generations.

If you fancy a read on all things cephie, consider picking up a copy of Cephalopods Present and Past: New Insights and Fresh Perspectives edited by Neil Landman and Richard Davis. Figure 16.2 is from page 348 of that publication and shows the hosting predation quite well. 

Photos: Courtesy of the deeply awesome Emil Black. These are in his personal collection that I hope to see in person one day. 

It was his sharing of the top photo and the strange anomaly that had me explore more about the fossils from Dubki and the weird and wonderful hosting relationship between ammonites and bivalves. Thank you, my friend!