KING OF THE TRILOBITES: UNEARTHING ISOTELUS REX

Isotelus rex, the King of Trilobites

In the remote limestone flats of northern Manitoba, a remarkable fossil lay undisturbed for nearly half a billion years. Sunken in gray stone, its broad armored body preserved in exquisite detail, it waited silently—until a team of Canadian paleontologists happened upon it during a summer field expedition in 1999.

What they uncovered would change the story of trilobites forever.

Meet Isotelus rex, the largest complete trilobite ever discovered—a 70-centimetre-long prehistoric titan from the Ordovician seas. It's more than just a big trilobite. It’s a window into an ancient world and a landmark find in Canadian paleontology.

A Fossil Giant in a Forgotten Sea

Trilobites, extinct marine arthropods, are among the most iconic fossils in the world. Their hard, segmented exoskeletons and alien-like eyes make them favorites among collectors and scientists alike. They first appeared more than 520 million years ago and thrived in Earth’s oceans for over 270 million years before vanishing in the Permian extinction.

Many trilobites are palm-sized or smaller. But Isotelus rex was something else entirely.

Discovered near William Lake in the Hudson Bay Lowlands of Manitoba, Isotelus rex was preserved in limestone laid down when central Canada was submerged beneath a warm, shallow sea. That sea teemed with life—brachiopods, nautiloids, sea lilies, and trilobites like Isotelus, which would have cruised the muddy bottom looking for food.

With its broad, paddle-shaped tail, deeply segmented body, and large compound eyes, Isotelus rex was a slow-moving but imposing presence on the seafloor.

The Paleontologists Behind the Discovery

The discovery was made by a team of seasoned Canadian researchers: Dr. David Rudkin of the Royal Ontario Museum, Dr. Graham Young and Edward Dobrzanske of the Manitoba Museum, and Dr. Robert Elias from the University of Manitoba. 

All were participating in a joint field expedition to study the fossil-rich limestone of the Churchill River Group, near Churchill in northern Manitoba.

Dr. Rudkin is one of Canada’s leading experts on Paleozoic arthropods, with a particular passion for trilobites and other ancient sea creatures. 

His work at the Royal Ontario Museum has helped bring the stories of long-extinct animals to life through detailed study and public exhibition.

Dr. Young, curator of geology and paleontology at the Manitoba Museum, specializes in ancient marine ecosystems—piecing together how life functioned and interacted in prehistoric oceans. 

Dr. Elias, a geologist and paleontologist at the University of Manitoba, focuses on Paleozoic reefs and ancient sedimentary environments. Dobrzanske, a collections technician and field expert, brought deep practical knowledge to the fieldwork.

It was the perfect blend of expertise and passion.

One overcast morning, while surveying outcrops of Ordovician limestone, the team spotted a familiar ripple in the rock—a faint curve suggesting a trilobite’s cephalon, or head shield. As they slowly and carefully uncovered more of the fossil, its remarkable size and completeness became apparent.

The mostly complete holotype specimen of Isotelus rex, from the Churchill River Group, measures a staggering 720 millimetres (28 inches) in length, 400 millimetres (16 inches) in maximum width across the cephalon, and 70 millimetres (3 inches) in height at the posterior midpoint of the head. It remains the largest complete trilobite ever found.

“We thought it might be a fluke,” Rudkin later recalled. “A fragment from a large individual. But as we kept going—it just kept going. That was when we realized we were looking at something truly extraordinary.”

Perfect Conditions for Preservation

Unlike many trilobite fossils, which are found in fragments or disarticulated pieces, Isotelus rex was remarkably well-preserved—fully articulated, lying in life position.

Paleontologists believe it was buried rapidly by fine carbonate mud, likely during a sudden underwater event like a storm or sediment slump. The seafloor at the time was likely anoxic—lacking oxygen—which would have prevented decay and scavenging, allowing the trilobite’s body to remain intact as minerals slowly fossilized it over millions of years.

“It’s one of the most complete large trilobites ever found anywhere in the world,” said Young. “It offers a rare look at what these creatures really looked like, in full form.”

While its size is headline-grabbing, Isotelus rex offers deeper scientific insights. It shows that trilobites—already known for their diversity—could grow far larger than previously thought. Its presence in northern Manitoba also highlights how much of Canada’s paleontological richness remains underexplored.

The fossil was later transported to Winnipeg, where it became a highlight of the Manitoba Museum’s paleontology collection. A custom case was built to display it—regular trilobite mounts just wouldn’t do for a specimen of this scale.

The name Isotelus rex—Latin for “equal end king”—reflects both its classification and its grandeur.

Today, Isotelus rex is more than just a museum centerpiece. It’s a reminder of the power of curiosity, collaboration, and exploration. It represents a frozen moment from 450 million years ago, when trilobites were the dominant animals of Earth’s seas.

And thanks to the eyes, hands, and minds of Rudkin, Elias, Young, and Dobrzanske, we now know what the king of trilobites looked like and he is an impressive specimen, indeed!

Image credit: Isotelus rex TMP 2009.003.0003 (cast). 445 million years old, late Ordovician, Churchill River Group, Churchill, Manitoba. At the Royal Tyrrell Museum of Palaeontology. Bloopityboop

GENAL SPINES A GO GO

Cibelella Coronata / Photo: Alexei Molchanov

A spectacular creamy toned specimen of the trilobite Cibelella Coronata striking a very animated pose. 

The Genal spines give this fellow a bit of a starship look as though taking off in flight. 

This beauty is from upper Ordovician deposits along the Neva River at the head of the Gulf of Finland on the Baltic Coast, Saint Petersburg, Russia.

HOLLARDOPS: LE MAÎTRE

Hollardops sp. Devonian Trilobite

Hollardops is a genus of trilobite in the order Phacopida that lived during the Eifelian of the Middle Devonian. It was described by Le Maître in 1952 under type species Metacanthina mesocristata. 

The genus underwent reclassification in 1997 and emerged as Hollardops. We find this extinct arthropod in present-day Morocco. They share similarities with Greenops of New York and Canada but are generally larger than most Greenops species.

Hollardops have schizochroal eyes and a glabella that is slightly raised on the surface of the cephalon. Genal spines extend from the cephalon and extend to approximately the 6th thoracic segment.

Hollardops has eleven thoracic segments and also has five pairs of spines extending from the segments of the pygidium. Length ranges from approximately 3 to 9 cm.

Palaeo Coordinates — If you are a keen bean to head out in search of this lovely yourself, head to the Tazoulait Formation at Jbel (Jebel) Oufatène 30.8374368°N 4.9018067°W and Issimour 30.9669834°N 5.0373266°W SE of Alnif, western of Oued Alnif, Ma'ider region, Morocco.

BRONZE BEAUTY: EIFELIAN PARALEJURUS

This bronzed beauty is the Middle Devonian, Eifelian (~395 mya) trilobite, Paralejurus rehamnanus (Alberti, 1970) from outcrops near Issoumour, Alnif, Morocco in North Africa. 

It was the colour of this amazing trilobite that captured the eye of David Appleton in whose collection it now resides. He is an avid collector and coming into his own as a macro photographer. I have shared three of his delightful photos for you here.

It initially thought that the gold we see here was added during prep, particularly considering the colouration of the matrix, but macro views of the surface show mineralization and the veins running right through the specimen into the matrix. There is certainly some repairs but that is common in the restoration of these specimens. Many of the trilobites I have seen from Morocco have bronze on black colouring but not usually this pronounced. Even so, there is a tremendous amount of fine anatomy to explore and enjoy in this wonderfully preserved specimen.  

Paralejurus is a genus of trilobite in the phylum Arthropoda from the Late Silurian to the Middle Devonian of Africa and Europe. These lovelies grew to be up to nine centimetres, though the fellow you see here is a wee bit over half that size at 5.3 cm. 

Paralejurus specimens are very pleasing to the eye with their long, oval outline and arched exoskeletons. 

Their cephalon or head is a domed half circle with a smooth surface.  The large facet eyes have very pleasing crescent-shaped lids. You can see this rather well in the first of the photos here. The detail is quite remarkable.

As you move down from his head towards the body, there is an almost inconspicuous occipital bone behind the glabella in the transition to his burnt bronze thorax.

The body or thorax has ten narrow segments with a clearly arched and broad axial lobe or rhachis. The pygidium is broad, smooth and strongly fused in contrast to the genus Scutellum in the family Styginidae, which has a pygidium with very attractive distinct furrows that I liken to the look of icing ridges on something sweet — though that may just be me and my sweet tooth talking. In Paralejurus, they look distinctly fused — or able to fuse — to add posterior protection against predators with both the look and function of Roman armour.

In Paralejurus, the axillary lobe is rounded off and arched upwards. It is here that twelve to fourteen fine furrows extend radially to complete the poetry of his body design. 

Trilobites were amongst the earliest fossils with hard skeletons and they come in many beautiful forms. While they are extinct today, they were the dominant life form at the beginning of the Cambrian. 

As a whole, they were amongst some of the most successful of all early animals — thriving and diversifying in our ancient oceans for almost 300 million years. The last of their brethren disappeared at the end of the Permian — 252 million years ago. Now, we enjoy their beauty and the scientific mysteries they reveal about our Earth's ancient history.

Photos and collection of the deeply awesome David Appleton. Specimen: 5.3 cm. 

THE DUDLEY BUG: ROLLED TRILOBITE

A lovely rolled trilobite, Calymene blumenbachii,  from outcrops in the UK. This wee beauty is in the collections of the deeply awesome Theresa Paul Spink Dunn — or perhaps in her daughter Layla's collections as she is quite the budding palaeontologist. This Silurian beauty is from the Homerian, Wenlock Series, Wrens Nest, Dudley, UK.

Calymene blumenbachii, sometimes erroneously spelled blumenbachi, is a species of trilobite found in the limestone quarries of the Wren's Nest in Dudley, England.

Nicknamed the Dudley Bug or Dudley Locust by an 18th-century quarryman, it became a symbol of the town and featured on the Dudley County Borough Council coat-of-arms. Calymene blumenbachii is commonly found in Silurian rocks (422.5-427.5 million years ago) and is thought to have lived in the shallow waters of the Silurian, in low energy reefs.

This particular species of Calymene — a fairly common genus in the Ordovician-Silurian — is unique to the Wenlock series in England and comes from the Wenlock Limestone Formation in Much Wenlock and the Wren's Nest in Dudley. 

These sites seem to yield trilobites more readily than any other areas on the Wenlock Edge, and the rock here is dark grey as opposed to yellowish or whitish as it appears on other parts of the Edge, just a few miles away, in Church Stretton and elsewhere suggesting local changes in the environment in which the rock was deposited. 

The Wenlock Edge quarry is closed now to further collecting but may be open to future research projects. We shall have to wait and see.

HOLLARDOPS: LE MAÎTRE

Hollardops sp. Devonian Trilobite

Hollardops is a genus of trilobite in the order Phacopida that lived during the Eifelian of the Middle Devonian. It was described by Le Maître in 1952 under type species Metacanthina mesocristata. 

The genus underwent reclassification in 1997 and emerged as Hollardops. We find this extinct arthropod in present-day Morocco. They share similarities with Greenops of New York and Canada but are generally larger than most Greenops species.

Hollardops have schizochroal eyes and a glabella that is slightly raised on the surface of the cephalon. Genal spines extend from the cephalon and extend to approximately the 6th thoracic segment.

Hollardops has eleven thoracic segments and also has five pairs of spines extending from the segments of the pygidium. Length ranges from approximately 3 to 9 cm.

Palaeo Coordinates — If you are a keen bean to head out in search of this lovely yourself, head to the Tazoulait Formation at Jbel (Jebel) Oufatène 30.8374368°N 4.9018067°W and Issimour 30.9669834°N 5.0373266°W SE of Alnif, western of Oued Alnif, Ma'ider region, Morocco.

BUENELLUS HIGGINSI FROM GREENLAND

An exceptional example of the Lower Cambrian trilobite Buenellus higginsi from the Sirius Passet Biota, Buen Formation which borders the Arctic Sea along the northernmost coast of Greenland, an island country that is part of the Kingdom of Denmark located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. If you look closely, you can see that this specimen shows preservation of gut.

Buenellus higginsi averages around 5 centimeters or 2 inches. There have been some interesting studies done on these trilobites regarding predation. 

The predation scars are typically arcuate and show evidence of repair, with distortion of the healed area

It is a prominent member of the Sirius Passet fauna. If you find one, you find oodles of them in the outcrop. Buenellus higginsi is the only known species in the genus Buenellus as the genus is monotypic.

LYSAKER MEMBER TRILOBITE

Niobe schmidti (Balashova, 1976)

This gorgeous trilobite is an exceptionally well-preserved Niobe schmidti (Balashova, 1976) from middle Ordovician limestone deposits of the Huk Formation, Lysaker member near Oslo, Norway. 

The limestones of the Huk Formation have an extreme geological history and fossils from this formation are usually very difficult to prepare. 

The beige/grey limestones are often heavily cemented to the shelly material, which can be quite fragile.

The rich chocolate coloured specimen you see here was no exception. It presented many challenges in its 26 hours of preparation but each of these was overcome by the patience and skill of Paul Freitag Wolvers at Freitag Fossils. 

I have added a link below with a series of photos so you can walk through the preparation process step by step with Paul. If you have a special specimen you would like prepped, I highly recommend you contact him. His work is outstanding.

Superb prep of this Niobe schmidti (Balashova, 1976)

The shell was partly hollow, very fragile and stuck firmly to the matrix. The positive was assembled from two pieces and much of the shell of the left half of the trilobite had to be transferred over from the negative — no small feat. 

Despite these challenges, the final result is superb. This Niobe schmidti is a museum-quality specimen with exquisite preservation. You can clearly see the lovely terrace lines, pores and eye lenses are excellent to study.  

This specimen hails from the middle Ordovician. The Ordovician lasted almost 45 million years, beginning 488.3 million years ago and ending 443.7 million years ago. 

It was the time in our Earth's history when the area north of the tropics was almost entirely underwater and most of the world's land was collected into the southern supercontinent of Gondwana. Throughout the Ordovician, Gondwana slowly shifted towards the South Pole and much of it remained submerged under an ancient ocean.

Niobe schmidti (Balashova, 1976)

At the time that this fellow was making a living in our ancient seas, he would have been joined by a diverse community of marine invertebrates —graptolites, fellow trilobites, brachiopods and the early vertebrate conodonts. 

These marine communities were joined by red and green algae, primitive fish, cephalopods, corals, crinoids, and gastropods. 

We also find stunning tetrahedral spores similar to those of primitive land plants which tell us who was living on the land at the time.

One of the first specimens of this lovely species I had the pleasure to see was from the Voybokalo Quarry near St. Petersburg in Russia. These outcrops are part of the Kunda Horizon, Lower Ordovician, Asaphus expansus zone and run roughly 468 million years old. 

From the Lower to Middle Ordovician, the Earth was enjoying a mild, humid climate — the weather was warm and the atmosphere contained a significant amount of moisture. 

Once Gondwana finally settled on the South Pole during the Upper Ordovician, massive glaciers formed. These drained the shallow seas and ocean levels dropped. By the end of the Ordovician, 60% of all marine invertebrates and 25% of all life on Earth disappeared as part of the Ordovician mass extinction event. We enjoy many of those species now only as fossils and if we are lucky, preserved in remarkable detail.

Photos & collection: Mark Wolvers. Preparation: Paul Freitag, Freitag Fossils. Specimen: 5.5 cm (2.16 inches). You can see some amazing photos of the transformation of this trilobite throughout Paul's preparation process here: https://freitag-fossils.com/en/niobe-schmidti/

If you click on any of the images, you can see them enlarged to take in all the wonderful detail. 

Reference: UCMP Berkeley / https://ucmp.berkeley.edu

ANCIENT LIFE IN THE EAST KOOTENAYS: ORYGMASPIS SPINULA

Orygmaspis (Parabolinoides) spinula

This calcified beauty is Orygmaspis (Parabolinoides) spinula (Westrop, 1986) an Upper Cambrian trilobite from the McKay Group near Tanglefoot Mountain in the Kootenay Rockies. 

Orygmaspis is a genus of asaphid trilobite with an inverted egg-shaped outline, a wide headshield, small eyes, long genal spines, 12 spined thorax segments and a small, short tail shield, with four pairs of spines.

The outline of the exoskeleton Orygmaspis is inverted egg-shaped, with a parabolic headshield — or cephalon less than twice as wide as long. 

The glabella, the well-defined central raised area excluding the backward occipital ring, is ¾× as wide as long, moderately convex, truncate-tapering, with 3 pairs of shallow to obsolete lateral furrows. 

The occipital ring is well defined. The distance between the glabella and the border (or preglabellar field) is ±¼× as long as the glabella. This fellow had small to medium-sized eyes, 12-20% of the length of the cephalon. These were positioned between the front and the middle of the glabella and about ⅓ as far out as the glabella is wide. 

The remaining parts of the cephalon, the fixed and free cheeks — or fixigenae and librigenae — are relatively flat. The fracture lines or sutures — that separate the librigenae from the fixigenae in moulting — are divergent just in front of the eyes. These become parallel near the border furrow and strongly convergent at the margin. 

From the back of the eyes, the sutures bend out, then in, diverging outward and backward at approximately 45°, cutting the posterior margin well within the inner bend of the spine — or opisthoparian sutures. 

The thorax or articulating middle part of the body has 12 segments. The anteriormost segment gradually narrows into a sideward directed point, while further to the back the spines are directed outward and the spine is of increasing length up until the ninth spine, while the spine on the tenth segment is abruptly smaller, and 11 and 12 even more so. 

This fellow has a wee pygidium or tail shield that is only about ⅓× as wide as the cephalon. It is narrowly transverse about 2× wider than long. Its axis is slightly wider than the pleural fields to each side, and has up to 4 axial rings and a terminal and almost reaches the margin. Up to 4 pleural segments with obsolete interpleural grooves and shallow pleural furrows. The posterior margin has 3 or 4 pairs of spines, getting smaller further to the back. 

References:

Chatterton, Brian D. E.; Gibb, Stacey (2016). Furongian (Upper Cambrian) Trilobites from the McKay Group, Bull River Valley, Near Cranbrook, Southeastern British Columbia, Canada; Issue 35 of Palaeontographica Canadiana; ISBN: 978-1-897095-79-9

Moore, R.C. (1959). Arthropoda I - Arthropoda General Features, Proarthropoda, Euarthropoda General Features, Trilobitomorpha. Treatise on Invertebrate Paleontology. Part O. Boulder, Colorado/Lawrence, Kansas: Geological Society of America/University of Kansas Press. pp. O272–O273. ISBN 0-8137-3015-5.

ANCIENT FOSSIL TRACKWAYS

Trilobite and Sea Scorpion Fossil Trackways

This is a very interesting block with wee trace fossil trackways from our Mississippian seas some 359.2 million to 318.1 million years ago. 

It shows a nice combination of Cruziana fossil trilobite trackway and eurypterid (sea scorpion) or horseshoe crab trackway on the same matrix. 

When we use the term Cruziana, we are not referring to the trilobite species, but to the particular shape and form of the trackway. 

In this case, elongate, bilaterally symmetrical burrows preserved along the bedding plane with repeated striations that are mostly oblique to the long dimension. I like to picture a teeny, tiny painter or sculpture with a small putty knife making angled cuts along a line or a wave motion to create a small curved line. Very showy skate skiing is another good visual. Sadly, neither is the case. While a Cruziana trace fossil is most often associated with trilobites, it can be made by other arthropods. 

When we see trace fossils — preserved tracks or other signs of behaviour from our marine friends living on the seafloor — they are generally from their furrowing, resting, emerging, walking or striding. They provide a glimpse of how these ancient sea creatures moved about to make a living. 

Trilobite and Sea Scorpion Fossil Trackways

This busy 4 1/2" x 3 1/2" x 1 1/4" block hails from the Tar Springs Formation in Perry County, Indiana, USA, and is in the collections of the deeply awesome David Appleton.

The Tar Springs Formation is recognized on the surface from southwestern Orange County to the Ohio River and is known in the subsurface from central Martin County southwestward (Gray, 1970, 1986).

In Indiana, the Tar Springs Formation is primarily shale, but it also contains scattered thin beds of limestone and massive local lenses of sandstone that on outcrop are differentiated as the Tick Ridge Sandstone Member (Gray, 1986). The formation ranges in thickness from about 70 ft (21 m) to more than 150 ft (46 m) in central Posey County and in southwestern Gibson County (Droste and Keller, 1995). Commonly sandstone predominates in those areas where the Tar Springs is as much as 150 ft (46 m) thick (Droste and Keller, 1995).

TRACKING THROUGH THE CAMBRIAN

Pterocephalia norfordi, McKay Group

A lovely Pterocephalia norfordi trilobite from Upper Cambrian, Furongian strata of the McKay Group, East Kootenay Region, southeastern British Columbia, Canada. 

The McKay Group has been explored extensively these past few years by Chris New and Chris Jenkins of Cranbrook, British Columbia. 

Together, these two avid trilobite enthusiasts have opened up considerable knowledge on the exposures, collaborating with researchers Brian Chatterton and Rudy Lerosey-Aubril. They have unearthed many new specimens and several new species. 

Pterocephalia from this region are relatively common. We also find Wujiajiania lyndasmithae along with a host of other Upper Cambrian goodies. 

I collected dozens of well-preserved fully articulated specimens over the course of a week in August 2020, walking in the sacred lands of the Ktunaxa or Kukin ʔamakis First Nations. 

My eyes were good enough to find the specimens themselves, but not as refined as those of Chris Jenkins who spotted the unusual preservation of the embedded gut tract. Brian Chatterton et al. published on it in 1994 and have been following it up year upon year with paper after paper out of these localities. 

Rudy Lerosey-Aubril published a paper in 2017 on phosphatized gut remains — relatively common in this taxon at this site. Lerosey-Aubril’s paper was on an aglaspidid, a combjelly, and the gut of another trilobite. 

Skeletal remains of trilobites are abundant in Palaeozoic rock but soft parts are rarely preserved. 

There have been a few papers on trilobite gut remains from Canada and on abundant trilobite faunas of the Kaili Formation of Guizhou, China. 

The Kaili contains one of the earliest middle Cambrian Burgess Shale-type deposits, sharing many faunal elements with the older Chengjiang Biota (Chen 2004; Hou et al. 2004) and the younger Burgess Shale Biota (Briggs et al. 1994). 

The biota, facies description, and regional stratigraphy of the Kaili Biota were discussed and reviewed in Zhao et al. (2002, 2005) and Lin et al. (2005). 

Their colleagues (Zhao et al. 1994b, 1996, 1999, 2001, 2002) have beautifully illustrated many Kaili arthropods with soft-part preservation, but most of their systematic descriptions are yet complete.

References: Chatterton BD, Johanson Z, Sutherland G. 1994. Journal of Paleontology 68:294-305. 

Lin, Jih-Pai. (2007). Preservation of the gastrointestinal system in Olenoides (Trilobita) from the Kaili Biota (Cambrian) of Guizhou, China. Memoirs of the Association of Australasian Palaeontologists. 33. 179-189. 

Top Photo: This specimen was collected by Dan Bowden and photographed by the Huntress. It has been checked for the dark telltale signs of phosphatized gut remains — sadly no luck!

Middle Photo: Warm summer light atop the mountains and my temporary home-sweet-home. Bottom Photo: Upper Cambrian collecting beds beneath Tanglefoot Mountain, McKay Group, East Kootenay Region, British Columbia, Canada.

LOWER CAMBRIAN EAGER FORMATION

This specimen of a mature olenellid trilobite, Wanneria dunnae, is from the Lower Cambrian Eager Formation of British Columbia. 

He is from the Rifle Range outcrop near Cranbrook where you can find numerous fragments and complete specimens of the olenellid trilobites Ollenellus sp. and the larger, more robust Wanneria sp. you see here. 

The site outcrops at a few locations as you head east out of Cranbrook towards Fort Steele. 

The first trilobites were discovered with the building of the Kootenay Highway connecting Cranbrook to Fort Steele and beyond. Several other localities, including the outcrops at the Silhouette Rife Range — which is literally on a Rifle Range where folks go to shoot at things — is a shade older than the Middle Cambrian Burgess Shale but the fauna here is much less varied. 

The site has been known and collected since the 1920s. Back in the day, fossil collecting was a family affair with folks heading out in their lightly coloured finery to picnic and surface collect the eroding exposures. Cranbrook local, Clement Hungerford Pollen was an engineer and avocational palaeontologist. 

He promoted collecting the exposures of the Eager Formation around 1921. As a pedigreed Englishman of considerable means, he had invested in the Kootenay Central Railway, revitalizing the town by opening up railway access within the region.

Olenellus ricei, Eager Formation

Olenellus is an extinct genus of redlichiid trilobites, with species of average size (about 5 centimetres or 2.0 inches long). He lived during the Botomian and Toyonian stages, Olenellus-zone, 522 to 510 million years ago, in what is currently North America, part of the paleocontinent Laurentia.

These extinct arthropods are common in Early Cambrian rocks — 542 million to 521 million years old — and thus a useful guide fossil for the Early Cambrian. 

Olenellus had a well-developed semi-circular head, large and crescentic eyes, and a poorly developed, small tail. Telltale features are his fifteen body segments with the third being much longer than the others. The fellow you see had a bit of his tail crushed as he turned to stone.

Trilobites were amongst the earliest fossils with hard skeletons. While they are extinct today, they were the dominant life form at the beginning of the Cambrian and it is what we find as the primary fossil fauna in the Eager Formation. The Eager Formation has produced many beautifully preserved Wanneria, abundant Olellenus and a handful of rare and treasured Tuzoia. The shale matrix lends itself to amazing preservation. The specimens of Wanneria from here are large. Some are up to thirteen centimetres long and ten centimetres wide. You find a mixture of complete specimens and head impressions from years of perfectly preserved moults.

NIOBE SCHMIDTI OF NORWAY

Niobe schmidti (Balashova, 1976)

This gorgeous trilobite is an exceptionally well-preserved Niobe schmidti (Balashova, 1976) from middle Ordovician limestone deposits of the Huk Formation, Lysaker member near Oslo, Norway. 

The limestones of the Huk Formation have an extreme geological history and fossils from this formation are usually very difficult to prepare. 

The beige/grey limestones are often heavily cemented to the shelly material, which can be quite fragile.

The rich chocolate coloured specimen you see here was no exception. It presented many challenges in its 26 hours of preparation but each of these was overcome by the patience and skill of Paul Freitag Wolvers at Freitag Fossils. 

I have added a link below with a series of photos so you can walk through the preparation process step by step with Paul. If you have a special specimen you would like prepped, I highly recommend you contact him. His work is outstanding.

Superb prep of this Niobe schmidti (Balashova, 1976)

The shell was partly hollow, very fragile and stuck firmly to the matrix. The positive was assembled from two pieces and much of the shell of the left half of the trilobite had to be transferred over from the negative — no small feat. 

Despite these challenges, the final result is superb. This Niobe schmidti is a museum-quality specimen with exquisite preservation. You can clearly see the lovely terrace lines, pores and eye lenses are excellent to study.  

This specimen hails from the middle Ordovician. The Ordovician lasted almost 45 million years, beginning 488.3 million years ago and ending 443.7 million years ago. 

It was the time in our Earth's history when the area north of the tropics was almost entirely underwater and most of the world's land was collected into the southern supercontinent of Gondwana. Throughout the Ordovician, Gondwana slowly shifted towards the South Pole and much of it remained submerged under an ancient ocean.

Niobe schmidti (Balashova, 1976)

At the time that this fellow was making a living in our ancient seas, he would have been joined by a diverse community of marine invertebrates —graptolites, fellow trilobites, brachiopods and the early vertebrate conodonts. 

These marine communities were joined by red and green algae, primitive fish, cephalopods, corals, crinoids, and gastropods. 

We also find stunning tetrahedral spores similar to those of primitive land plants which tell us who was living on the land at the time.

One of the first specimens of this lovely species I had the pleasure to see was from the Voybokalo Quarry near St. Petersburg in Russia. These outcrops are part of the Kunda Horizon, Lower Ordovician, Asaphus expansus zone and run roughly 468 million years old. 

From the Lower to Middle Ordovician, the Earth was enjoying a mild, humid climate — the weather was warm and the atmosphere contained a significant amount of moisture. 

Once Gondwana finally settled on the South Pole during the Upper Ordovician, massive glaciers formed. These drained the shallow seas and ocean levels dropped. By the end of the Ordovician, 60% of all marine invertebrates and 25% of all life on Earth disappeared as part of the Ordovician mass extinction event. We enjoy many of those species now only as fossils and if we are lucky, preserved in remarkable detail.

Photos & collection: Mark Wolvers. Preparation: Paul Freitag, Freitag Fossils. Specimen: 5.5 cm (2.16 inches). You can see some amazing photos of the transformation of this trilobite throughout Paul's preparation process here: https://freitag-fossils.com/en/niobe-schmidti/

If you click on any of the images, you can see them enlarged to take in all the wonderful detail. 

Reference: UCMP Berkeley / https://ucmp.berkeley.edu

CRUZIANA TRILOBITE AND ANCIENT FOSSIL TRACKWAYS

Trilobite and Sea Scorpion Fossil Trackways

This is a very interesting block with wee trace fossil trackways from our Mississippian seas some 359.2 million to 318.1 million years ago. 

It shows a nice combination of Cruziana fossil trilobite trackway and eurypterid (sea scorpion) or horseshoe crab trackway on the same matrix. 

When we use the term Cruziana, we are not referring to the trilobite species, but to the particular shape and form of the trackway. 

In this case, elongate, bilaterally symmetrical burrows preserved along the bedding plane with repeated striations that are mostly oblique to the long dimension. I like to picture a teeny, tiny painter or sculpture with a small putty knife making angled cuts along a line or a wave motion to create a small curved line. Very showy skate skiing is another good visual. Sadly, neither is the case. While a Cruziana trace fossil is most often associated with trilobites, it can be made by other arthropods. 

When we see trace fossils — preserved tracks or other signs of behaviour from our marine friends living on the seafloor — they are generally from their furrowing, resting, emerging, walking or striding. They provide a glimpse of how these ancient sea creatures moved about to make a living. 

Trilobite and Sea Scorpion Fossil Trackways

This busy 4 1/2" x 3 1/2" x 1 1/4" block hails from the Tar Springs Formation in Perry County, Indiana, USA, and is in the collections of the deeply awesome David Appleton.

The Tar Springs Formation is recognized on the surface from southwestern Orange County to the Ohio River and is known in the subsurface from central Martin County southwestward (Gray, 1970, 1986).

In Indiana, the Tar Springs Formation is primarily shale, but it also contains scattered thin beds of limestone and massive local lenses of sandstone that on outcrop are differentiated as the Tick Ridge Sandstone Member (Gray, 1986). The formation ranges in thickness from about 70 ft (21 m) to more than 150 ft (46 m) in central Posey County and in southwestern Gibson County (Droste and Keller, 1995). Commonly sandstone predominates in those areas where the Tar Springs is as much as 150 ft (46 m) thick (Droste and Keller, 1995).

TRILOBITES: DARLINGS OF THE FOSSIL RECORD

Trilobites are the darlings of most fossil collectors. These diverse beauties are an extinct group of marine arthropods that first appeared in the Early Cambrian. 

They left many beautifully preserved examples of their three-lobed exoskeletons in the fossil record.

Trilobites — in all their many wonderful forms — lived in our ancient oceans for more than 270 million years. The last of their lineage went extinct at the end of the Permian, 252 million years ago. 

MEET ACICULOLENUS ASKEWI: A NEW UPPER CAMBRIAN TRILOBITE

A new species of trilobite from the upper Cambrian McKay Group was introduced in March of 2020: Aciculolenus askewi.  The species is named after Don Askew, an avid fossil hunter of Upper Cambrian trilobites from Cranbrook, British Columbia, Canada, who has discovered several new species in the East Kootenays. 

Don was the first to brave the treacherous cliffs up the waterfall on the west side of the ravine below Tanglefoot mountain. That climb led to his discovery of one of the most prolific outcrops in the McKay Group with some of the most exciting and best-preserved trilobites from the region. 

The faunal set are similar to those found at site one — the first of the trilobite outcrops discovered by Chris New and Chris Jenkins — an hours hike through grizzly bear country.

The specimens found at the top of the waterfall are not in calcite wafers, as they are elsewhere, instead, these exceptionally preserved specimens are found complete with a thin coating of matrix that must be prepped down to the shell beneath. 

Askew was also the skill preparator called upon to tease out the details from the 'gut trilobite' recently published from the region. In all, this area has produced more than 60 new species — many found by Askew — and not all of which have been published yet.

I caught up with Don last summer on a trip to the region. He was gracious in openly sharing his knowledge and a complete mountain goat in the field — a good man that Askew. 

Not surprising then that Brian Chatterton would do him the honour of naming this new species after him. 

Chatterton, Professor Emeritus at the University of Alberta, is an invertebrate palaeontologist with a great sense of humour and a particular love of trilobites. Even so, his published works span a myriad of groups including conodonts, machaeridians, sponges, brachiopods, corals, cephalopods, bivalves, trace fossils — to fishes, birds and dinosaurs.

Brian Chatterton has been visiting the East Kootenay region for many years. In 1998, he and Rolf Ludvigsen published the pivotal work on the "calcified trilobites" we had begun hearing about in the late 1990s. There were tales of blue trilobites in calcified layers guarded by a resident Grizzly. This was years before logging roads had reached this pocket of paleontological goodness and hiking in — bear or no bear — was a daunting task. 

In his Cambridge University Press paper, Chatterton describes the well-preserved fauna of largely articulated trilobites from three new localities in the Bull River Valley. 

The Dream Team at Fossil Site #15, East Kootenays, August 2, 2020

All the trilobites from these localities are from the lower or middle part of the Wujiajiania lyndasmithae Subzone of the Elvinia Zone, lower Jiangshanian, in the McKay Group. 

Access is via a bumpy ride on logging roads 20 km northeast of Fort Steele that includes fording a river (for those blessed with large tires and a high wheelbase) and culminating in a hot, dusty hike and death-defying traipse down 35-degree slopes to the localities.

Two new species were proposed with types from these localities: Aciculolenus askewi and Cliffia nicoleae. 

The trilobite (and agnostid) fauna from these localities includes at least 20 species that read like a who's who of East Kootenay palaeontology: 

Aciculolenus askewi n. sp., Agnostotes orientalis (Kobayashi, 1935), Cernuolimbus ludvigseni Chatterton and Gibb, 2016, Cliffia nicoleae n. sp., Elvinia roemeri (Shumard, 1861), Grandagnostus? species 1 of Chatterton and Gibb, 2016, Eugonocare? phillipi Chatterton and Gibb, 2016, Eugonocare? sp. A, Housia vacuna (Walcott, 1912), Irvingella convexa (Kobayashi, 1935), Irvingella flohri Resser, 1942, Irvingella species B Chatterton and Gibb, 2016, Olenaspella chrisnewi Chatterton and Gibb, 2016, Proceratopyge canadensis (Chatterton and Ludvigsen, 1998), Proceratopyge rectispinata (Troedsson, 1937), Pseudagnostus cf. P. josepha (Hall, 1863), Pseudagnostus securiger (Lake, 1906), Pseudeugonocare bispinatum (Kobayashi, 1962), Pterocephalia sp., and Wujiajiania lyndasmithae Chatterton and Gibb, 2016.

Chris New, pleased as punch atop Upper Cambrian Exposures

It has been the collaborative efforts of Guy Santucci, Chris New, Chris Jenkins, Don Askew and Stacey Gibb that has helped open up the region — including finding and identifying many new species or firsts including Pseudagnostus securiger, a widespread early Jiangshanian species not been previously recorded from southeastern British Columbia. 

Other interesting invertebrate fossils from these localities include brachiopods, rare trace fossils, a complete silica sponge (Hyalospongea), and a dendroid graptolite. 

The species we find here are more diverse than those from other localities of the same age in the region — and enjoy much better preservation. 

The birth of new species into our scientific nomenclature takes time and the gathering of enough material to justify a new species name.

Fortunately for Labiostria gibbae, specimens had been found of this rare species had been documented from the upper part of Wujiajiania lyndasmithae Subzone — slightly younger in age. 

Combined with an earlier discovery, they provided adequate type material to propose the new species — Labiostria gibbae — a species that honours Stacey Gibb and which will likely prove useful for biostratigraphy.

Reference: https://www.cambridge.org/core/journals/journal-of-paleontology/article/abs/midfurongian-trilobites-and-agnostids-from-the-wujiajiania-lyndasmithae-subzone-of-the-elvinia-zone-mckay-group-southeastern-british-columbia-canada/E8DBC8BD635863E840715122C05BB14A#

Photo One: Aciculolenus askewi by Chris Jenkins, Cranbrook, British Columbia

Photo Two: L to R: Dan Bowden, Guy Santucci, Chris Jenkins, Dan Askew and John Fam at Fossil Site #15, East Kootenay Region, British Columbia, Canada, August 2, 2020.

Photo Three: Chris New pleased as punch atop of Upper Cambrian Exposures in the East Kootenay Region, British Columbia, Canada

GUT TRILOBITE: TAGMOSIS IN AGLASPIDID ARTHROPODS

Orygmaspis (Parabolinoides) contracta with gut structure

This specimen lovely chocolate brown trilobite specimen is Orygmaspis (Parabolinoides) contracta — one of the most exciting trilobites to come out of the McKay Group in the East Kootenay Region of British Columbia, Canada.

And what is most exciting about this specimen is that there is clear preservation of some of the gut structures preserving this trilobite's last meal.

Documentation of non- or weakly biomineralizing animals that lived during the Furongian is essential for a comprehensive understanding of the diversification of metazoans during the early Palaeozoic. 

Biomineralization, biologically controlled mineralization, occurs when crystal morphology, growth, composition, and location is completely controlled by the cellular processes of a specific organism. Examples include the shells of invertebrates, such as molluscs and brachiopods. The soft bits of those same animals tend to rot or be scavenged long before mineralization or fossilization can occur — hence, we find less of them.

So, not surprisingly, the fossil record of soft-bodied metazoans is particularly scarce for this critical time interval. To date, the fossils we do have are relatively rare and scattered at a dozen or so localities worldwide. 

Location and stratigraphy of the Fossil Locality

This is one of the reasons that the soft gut structures from this Orygmaspis contracta trilobite are particularly exciting. 

This specimen was found in Upper Cambrian exposures in the Clay Creek section at the top of the left fork of the ravine below Tanglefoot Mountain, 20 km northeast of Fort Steele. 

It was the keen eyes of Chris Jenkins who noticed the interesting structures worthy of exploration.

Lerosey-Aubril along with colleagues, Patterson, Gibb and Chatterton, published a great study on this trilobite in Gondwana Research, February 2017. 

Their work looked at this new occurrence of exceptional preservation in Furongian (Jiangshanian) strata of the McKay Group near Cranbrook, British Columbia, Canada. Their study followed up on the work of Chatterton et al. studying trilobites with phosphatised guts in this same 10-m-thick interval. 

Lerosey-Aubril et al.'s paper looked at two stratigraphically higher horizons with soft-tissue preservation. One yielded a ctenophore and an aglaspidid arthropod, the other a trilobite with a phosphatised gut belonging to a different species than the previously described specimens. 

Undetermined ctenophore

The ctenophore represents the first Furongian record of the phylum and the first reported occurrence of Burgess Shale-type preservation in the upper Cambrian of Laurentia. 

The aglaspidid belongs to a new species of Glypharthrus, and is atypical in having twelve trunk tergites and an anteriorly narrow ‘tailspine’. These features suggest that the tailspine of aglaspidids evolved from the fusion of a twelfth trunk segment with the telson. 

They also confirm the vicissicaudatan affinities of these extinct arthropods. Compositional analyses suggest that aglaspidid cuticle was essentially organic with a thin biomineralised (apatite) outer layer. 

Macro imagery of the trilobite reveals previously unknown gut features — medial fusion of digestive glands — possibly related to enhanced capabilities for digestion, storage, or the assimilation of food. 

These new fossils show that conditions conducive to soft-tissue preservation repeatedly developed in the outer shelf environment represented by the Furongian strata near Cranbrook. Future exploration of the c. 600-m-thick, mudstone-dominated upper part of the section is ongoing by Chris New, Chris Jenkins and Don Askey. There work and collaboration will likely result in more continued discoveries of exceptional fossils.

Glypharthrus magnoculus sp.

The specimen you see here was expertly prepped by Don Askew of Cranbrook, British Columbia. It now resides in collections at the Royal BC Museum.

Photo One: Orygmaspis (Parabolinoides) contracta (Trilobita) from the Jiangshanian (Furongian) part of the McKay Group, Clay Creek section, near Cranbrook, British Columbia, Canada. A–D, specimen RBCM.EH2016.031.0001.001, complete dorsal exoskeleton preserved dorsum-down and showing ventral features, such as the in situ hypostome and phosphatised digestive structures. 

A, general view, specimen immersed under ethanol; B, detail of the digestive structures, specimen under ethanol; C, same as B, electron micrograph; D, same as B and C, interpretative drawing with digestive tract in blue-purple and digestive glands in pink. 

Abbreviations: Dc 1 and 2, cephalic digestive glands 1 and 2, Dt1 and 5, thoracic digestive glands 1 and 5, hyp, hypostome, L2, glabellar lobe 2, LO, occipital lobe, T1 and 5, thoracic segments 1 and 5. Scale bars represent 2 mm (A) and 1 mm (B–D). For interpretation of the references to the colours in this figure legend, you'll want to read the full article in the link below. 

Photo Two:  Undetermined ctenophore from the Jiangshanian (Furongian) part of the McKay Group, Clay Creek section, near Cranbrook, British Columbia, Canada. A, B, specimen UA 14333, flattened body fragment with oral-aboral axis oriented parallel to bedding; specimen photographed immersed under dilute ethanol with presumed oral region facing to the bottom. A, general view. B, detailed view showing comb rows and ctene. Scale bars represent 1 cm (A) and 5 mm (B). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)  

Photo Three: Glypharthrus magnoculus sp. nov. from the Jiangshanian (Furongian) part of the McKay Group, Clay Creek section, near Cranbrook, British Columbia, Canada. A–H, holotype, UA 14332, almost complete dorsal exoskeleton; photographs (A–C) and electron micrographs (D, backscattered; E–H, secondary) of the specimen in dorsal view with anterior facing to the top. A, B, general view in normal (A) and inverted (B) colours; C, D, detail of posterior trunk region, showing T12 and its contacts with T11 and the spiniform telson (arrows); the core of the fossil is made of a clay mineral and was initially entirely covered by an apatitic thin layer (white areas on D); E, left eye; F, right posterolateral glabellar lobe; G, rounded tubercles on right posterior border of cephalon; H, triangular tubercles pointing backwards (bottom right corner) on trunk axial region. Scale bars represent 5 mm (A, B), 1 mm (C, D), 500 μm (E, F), and 100 μm (G, H).

Link to the paper: https://www.researchgate.net/publication/309549546_Exceptionally-preserved_late_Cambrian_fossils_from_the_McKay_Group_British_Columbia_Canada_and_the_evolution_of_tagmosis_in_aglaspidid_arthropods

PTEROCEPHALIA FROM THE MCKAY GROUP

A lovely Pterocephalia trilobite from Upper Cambrian, Furongian strata of the McKay Group, Kootenay Rockies. 

The McKay Group has been explored extensively these past few years by Chris New and Chris Jenkins of Cranbrook, British Columbia. 

Together, these two avid trilobite enthusiasts have opened up considerable knowledge on the exposures, collaborating with researchers such as Brian Chatterton and Rudy Lerosey-Aubril. They have unearthed many new specimens and several new species. 

Pterocephalia from this region are relatively common. It was the keen eyes of Chris Jenkins that spotted the unusual preservation of the gut tract that led to the publication by Chatterton et al. in 1994. 

Rudy Lerosey-Aubril published a paper in 2017 on phosphatized gut remains — relatively common in this taxon at this site. Lerosey-Aubril’s paper was on an aglaspidid, a combjelly, and the gut of another trilobite. 

Skeletal remains of trilobites are abundant in Palaeozoic rock but soft parts are rarely preserved. There have been a few papers on trilobite gut remains from Canada and on abundant trilobite faunas of the Kaili Formation of Guizhou, China. The Kaili contains one of the earliest middle Cambrian Burgess Shale-type deposits, sharing many faunal elements (see http://hdl.handle.net/1811/24227) with the older Chengjiang Biota (Chen 2004; Hou et al. 2004) and the younger Burgess Shale Biota (Briggs et al. 1994). 

The biota, facies description, and regional stratigraphy of the Kaili Biota were discussed and reviewed in Zhao et al. (2002, 2005) and Lin et al. (2005). Chinese colleagues (Zhao et al. 1994b, 1996, 1999, 2001, 2002) have illustrated many Kaili arthropods with soft-part preservation, but most of their systematic descriptions are yet to be completed.

References: Chatterton BD, Johanson Z, Sutherland G. 1994. Journal of Paleontology 68:294-305. 

Lin, Jih-Pai. (2007). Preservation of the gastrointestinal system in Olenoides (Trilobita) from the Kaili Biota (Cambrian) of Guizhou, China. Memoirs of the Association of Australasian Palaeontologists. 33. 179-189. 

Photo: This specimen was collected by Dan Bowden and photographed by the Huntress. It has been checked for the dark telltale signs of phosphatized gut remains, but sadly no luck!

THE DUDLEY BUG

Calymene blumenbachii, Theresa Paul Spink Dunn

A lovely example of the trilobite Calymene blumenbachii from outcrops in the UK. This wee rolled beauty is in the collections of Theresa Paul Spink Dunn. This Silurian trilobite is from the Homerian, Wenlock Series, Wrens Nest, Dudley, UK.

Calymene blumenbachii, sometimes erroneously spelled blumenbachi, are found in the limestone quarries of the Wren's Nest in Dudley, England. This locality name was charmingly highjacked by an 18th-century quarryman birth the nickname the Dudley Bug — both a symbol of the town and a key feature on the Dudley County Borough Council Coat-of-Arms. Calymene blumenbachii is commonly found in Silurian rocks — 422.5-427.5 million years ago — that formed near shallow water, low energy reefs.

This particular species of Calymene — a fairly common genus in the Ordovician-Silurian — is unique to the Wenlock series in England and comes from the Wenlock Limestone Formation in Much Wenlock and the Wren's Nest in Dudley. These sites seem to yield trilobites more readily than any other areas on the Wenlock Edge. The rock here is dark grey and quite fossiliferous. Just a few miles away in Church Stretton and along other parts of the Edge, it is yellowish or whitish — an indication that there were local changes in the environment in which the rock was deposited. The Wenlock Edge quarry is closed to further collecting but may reopen for future research projects.

HYPODICRANOTUS STRIATULUS OF ONTARIO

Hypodicranotus striatulus

Take a gander at this unusual trilobite, Hypodicranotus striatulus (Walcott, 1875), with his gloriously bulbous head shield. Missing from this specimen is the wonderful forked hypostome from the dorsal exoskeleton that marks him as H. striatulus.

He’s from outcrops in the Verulam Formation, Bowmanville, Ontario, Canada. He lived in a deep subtidal environment as a nektobenthic deposit feeder some 460.9 to 449.5 million years ago.

These extinct pelagic trilobites are in the order Asaphida in the family Remopleuridae. Specimens have been found in Middle Ordovician marine outcrops from Ontario, Canada (this fellow is from here), the Northwest Territories, Quebec and in New York State, United States. Some of his sister taxa also in Remopleurididae (Hawle and Corda, 1847)  have been found in the Northwest Territories, Quebec, the UK and in Iowa, Wisconsin and Nevada. Collection of the awesome Marc R. Hänsel