UNRAVELLING THE CARNIAN-NORIAN BOUNDARY

Berlin-Ichthyosaur State Park

The Berlin-Ichthyosaur State Park in central Nevada is an important locality for our understanding of the Carnian-Norian boundary (CNB) in North America.

The area is also known worldwide as one of the most important ichthyosaur Fossil-Lagerstätte because of the sheer volume of remarkably well-preserved, fully articulated specimens of Shonisaurus popularis.

Rich ammonoid faunas outcrop in the Upper Triassic (Early Norian, Kerri zone), Luning Formation, West Union Canyon, Nevada. They were studied by N. J. Silberling (1959) and provide support for the definition of the Schucherti and Macrolobatus zones of the latest Carnian — which are here overlain by well-preserved faunas of the earliest Norian Kerri Zone. 

The genus Gonionotites, very common in the Tethys and British Columbia, is for the moment, unknown in Nevada. The Upper Carnian faunas are dominated by Tropitidae, while Juvavitidae are conspicuously lacking. 

Middle Triassic Ammonoids

Despite its importance, no further investigations had been done at this site for a good 50 years. That changed in 2010 when Jim Haggart, Mike Orchard and Paul Smith — all local Vancouverites — collaborated on a project that took them down to Nevada to look at the conodonts and ammonoids. They did a bed-by-bed sampling of ammonoids and conodonts in West Union Canyon during October of that year.

October is an ideal time to do fieldwork in this area. There are a few good weeks between screaming hot and frigid cold. It is also tarantula breeding season so keep your eyes peeled. Those sweet little burrows you see are not from rodents but rather largish arachnids. 

The eastern side of the canyon provides the best record of the Macrolobatus Zone, which is represented by several beds yielding ammonoids of the Tropites group, together with Anatropites div. sp. 

Conodont faunas from both these and higher beds are dominated by ornate metapolygnthids that would formerly have been collectively referred to Metapolygnathus primitius, a species long known to straddle the CNB. Within this lower part of the section, they resemble forms that have been separated as Metapolygnathus mersinensis. Slightly higher, forms close to Epigondolella' orchardi and a single Orchardella n. sp. occur. This association can be correlated with the latest Carnian in British Columbia.

Higher in the section, the ammonoid fauna shows a sudden change and is dominated by Tropithisbites. Few tens of metres above, but slightly below the first occurrence of Norian ammonoids Guembelites jandianus and Stikinoceras, two new species of conodonts (Gen et sp. nov. A and B) appear that also occur close to the favoured Carnian/Norian boundary at Black Bear Ridge, British Columbia. Stratigraphically higher collections continue to be dominated by forms close to M. mersinensis and E. orchardi after BC's own Mike Orchard.

The best exposure of the Kerri Zone is on the western side of the West Union Canyon. Ammonoids, dominated by Guembelites and Stikinoceras div. sp., have been collected from several fossil-bearing levels. Conodont faunas replicate those of the east section. The collected ammonoids fit perfectly well with the faunas described by Silberling in 1959, but they differ somewhat from coeval faunas of the Tethys and Canada. 

The ammonoid fauna paints a compelling picture of Tethyan influence with a series of smoking guns. We see an abundance of Tropitidae in the Carnian, a lack of Pterosirenites in the Norian, copious Guembelites, the Tethyan species G. philostrati, the stratigraphic position of G. clavatus and the rare occurrence of Gonionotites. Their hallelujah moment was likely finding an undescribed species of the thin-shelled bivalve Halobia similar to Halobia beyrichi — the clincher that perhaps seals this deal on Tethyan influence. 

I'll take a boo to see what Christopher McRoberts published on the find. A jolly good idea to have him on this expedition as it would have been easy to overlook if the focus remained solely on the conodonts and ammonoids. McRoberts has published on the much-studied Pardonet Formation up in the Willison Lake Area of Northeastern, British Columbia. He knows a thing or two about Upper Triassic Bivalvia and the correlation to coeval faunas elsewhere in the North American Cordillera, and to the Boreal, Panthalassan and Tethyan faunal realms. 

If you fancy a read, they published a paper: "Towards the definition of the Carnian/Norian Boundary: New data on Ammonoids and Conodonts from central Nevada," which you can find in the proceedings of the 21st Canadian Paleontology Conference; by Haggart, J W (ed.); Smith, P L (ed.); Canadian Paleontology Conference Proceedings no. 9, 2011 p. 9-10.

Fig. 1. Location map of Berlin-Ichthyosaur State Park

Marco Balini, James Jenks, Riccardo Martin, Christopher McRoberts, along with Mike Orchard and Norman Siberling, did a bed by bed sampling in 2013 and published on The Carnian/Norian boundary succession at Berlin-Ichthyosaur State Park (Upper Triassic, central Nevada, USA) and published in January 2014 in Paläontologische Zeitschrift 89:399–433. That work is available for download from ResearchGate. The original is in German, but there is a translation available.

After years of reading about the correlation between British Columbia and Nevada, I had the very great pleasure of walking through these same sections in October 2019 with members of the Vancouver Paleontological Society and Vancouver Island Palaeontological Society. It was with that same crew that I'd originally explored fossil sites in the Canadian Rockies in the early 2000s. Those early trips led to paper after paper and the exciting revelations that inspired our Nevada adventure.

If you plan your own adventure, you'll want to keep an eye out for some of the other modern fauna — mountain lions, snakes, lizards, scorpions, wolves, coyotes, foxes, ground squirrels, rabbits, falcons, hawks, eagles, bobcats, sheep, deer and pronghorns.

Figure One: Location map of Berlin-Ichthyosaur State Park. A detailed road log with access information for this locality is provided in Lucas et al. (2007).

CEPHALOPODS OF HALLSTATT

This beautiful slab of well-preserved Triassic, Carnian, upper Tuvalian ammonoids hails limestone outcrops near the salt-mining town of Hallstatt, Salzburgerland, Austria.

This area of the world boasts one of the richest deposits of Triassic ammonite units — more than five hundred magnificent ammonite species are found here along with a diversified selection of cephalopod fauna  — orthoceratids, nautiloids, ammonoids — we also see gastropods, bivalves (including lovely halobiids), brachiopods, crinoids and a few corals. For microfauna, we see conodonts, foraminifera, sponge spicules, radiolaria, floating crinoids and holothurian sclerites —  polyp-like, soft-bodied "wormy" invertebrate echinozoans. On the left, you can see two specimens of Jovites bosniensis MOJS. The ammonoid in the middle of the plate is Juvavites sp. The right side of the block shows two Hypocladiscites subtornatus MOJS.

The larger specimen (15cm) is a phragmocone. Within its badly crushed body chamber (removed during prep) there are two washed in specimens of Disotropites plinii (MOJS.) You can see them visible in the side view on the top right. The Disotropites plinii subzone is the lower ammonoid subzone of the Tuvalian III.

The second picture here shows Hypocladiscites subtornatus from when it was first described as Arcestes subtornatus, in Mojs, 1873.

In the North American literature (after Tim Tozer) the Tuvalian is split into three Zones; starting with the Dilleri Zone, then the Welleri Zone and finally the Macrolobatus Zone on the very top.

The Dilleri zone is characterized by the rise of the genus Tropites sp. together with later members of the genus Neoprotrachyceras sp.

In the Welleri zone, Neoprotrachyceras sp. disappears and Tropites becomes a very common faunal element. The Macrolobatus zone is named after Klamathites macrolobatus, an endemic ammonite of the North American strata. Other genera of this zone are comparable to the time frame of the latest Tuvalian and the earliest Norian of the Alps. In the Hallstatt (Tethys) realm the following Division is made:

Dilleri Zone= Tuvalian I (literature gives little evidence for this zone). Subbullatus Zone = Tuvalian II — corresponding in most parts to the North American Welleri Zone. These are followed by the Anatropites Zone or Tuvalian III — corresponding in part to the North American Macrolobatus Zone.

In the Alps, the strata are divided between Tuvalian II and Tuvalian III. It is up for debate if all three North American zones can be included in these two alpine zones. It has been postulated by Spatzenegger that there is little evidence for a time gap in the lower Tuvalian of the Alpine strata.

Discotropites sandlingense is in the North America zone — a clear Dilleri faunal element. In the Alps, it is ranged into Tuvalian II (Welleri Zone). The same is true for the genus Traskites sp. — corresponding to alpine Sandlingites sp. Some ammonites of the upper part of the Macrolobatus zone are also placed within the alpine Norian stage. The correlation between the North American and Alpine zones is problematic and matching up the Tuvalian fauna is a tricky business.

Sirenites sp., Upper Triassic, Lower Carnian Julian Zone

Tuvalian 1 is recognizable in the Alps by the composition of the faunal spectrum — the quantity of some special genera. We see more of some, less of others, and this gives us a general sense of time.

In some strata, Trachysagenites sp. Sagenites inermis, Sandlingites sp. occur frequently together, with scarce Tropites sp. and Sirenites sp. and (very rarely) Neoprotrachyceras cf. thyrae.

The transition from Tuvalian to the Norian is confirmed only in one location in the Hallstatt limestone. Clustered onto blocks, the ammonoids show us the faunal mix and allow us to place them in time. The bedded profile of Tuvalian fauna (which is overlain by a Norian fauna) hails from the Feuerkogel near Hallstatt. Here we also find the lower transition of Julian to Tuvalian. Not far from this site are limestone outcrops that show the transition between the Carnian and Norian. Here the latest Tuvalian and lowermost Norian are confirmed only by the microfossil fauna.

The Hallstatt Limestone is the world's richest Triassic ammonite unit, yielding specimens of more than 500 ammonite species. Along with diversified cephalopod fauna — orthoceratids, nautiloids, ammonoids — we also see gastropods, bivalves (esp. halobiids), brachiopods, crinoids and a few corals.

Along with an amazing assortment of macrofossils, we see microfauna that are incredibly helpful in teasing out the geologic history of the area. Fossil conodonts, foraminifera, sponge spicules, radiolaria, floating crinoids and the bizarre holothurian sclerites — polyp-like, soft-bodied invertebrate echinozoans often referred to as sea cucumbers because of their similarities in size, elongate shape, and tough skin over a soft interior — can be found here.

Eduard Suess, Gondwana / Tethys Sea

Franz Ritter von Hauer’s exhaustive 1846 tome describing Hallstatt ammonites inspired renowned Austrian geologist Eduard Suess’s detailed study of the area’s Mesozoic history.

That work was instrumental in Suess being the first person to recognize the supercontinent of Gondwana (proposed in 1861) and the existence of the Tethys Sea, which he named in 1893 after the sister of Oceanus, the Greek god of the ocean.

Suess Land in Greenland, as well as the lunar crater Suess and Suess crater on Mars, are named after him.

The Hallstatt-Meliata Ocean was one such back-arc basin. As it continued to expand and deepen during the Triassic, evaporation ceased and reefs flourished; thick limestone deposits accumulated atop the salt. When the Hallstatt-Meliata Ocean closed in the Late Jurassic, the compression squeezed the low-density salt into a diapir that rose buoyantly, injecting itself into the Triassic limestones above.

This area has a rich and interesting geological and human history. I'm sure more studies will be done on the fossil marine fauna to untangle and standardize the Carnian subdivisions. For now, we'll muddle along with regional stratigraphies employing a two-substage subdivision, the Julian and Tuvalian. Others will continue to employ a three-substage organization of the stage: Cordevolian, Julian and Tuvalian. 

As I've pieced together this interesting Tuvalian tale, I have to thank Andreas Spatzenegger from Salzburg, Austria for his insights, work and amazing photos of the area. Kudos to you, my friends. I'd be mesmerized but still well confused about the Carnian subdivisions if not for you!

The genus Hypocladiscites ranges from the base Carnian to the lower Norian stage of the Upper Triassic. Photos and collection of the deeply awesome Andreas Spatzenegger of Salzburg, Austria.

Superfamilia: Arcestaceae MOJSISOVICS, 1875; Familia: Cladiscitidae ZITTEL, 1884; Subfamilia: Cladiscites GAMSJÄGER, 1982; Genus: Hypocladiscites MOJSISOVICS, 1896

Photo: A spectacular example of Sirenites sp., Upper Triassic, Lower Carnian, Julian Zone of Trachyceras aonoides. From Hallstatt Limestone of Austria. This specimen is about 5cm. Photo and collection of the deeply awesome Andreas Spatzenegger.

Photo: Eduard Suess (1831–1914), lithograph by Josef Kriehuber (1800–1876) c. 1869 by Josef Kriehuber - File:Eduard Sueß.jpg (cropped), Public Domain https://commons.wikimedia.org/w/index.php?curid=31526345

TRIASSIC EPIGYMNITES OF HALLSTATT

Epigymnites arthaberi (MOJS.) and Epigymnites moelleri (MOJS.) Photo: Andreas

It was the Austrian geologist, Alexander Bittner, a contemporary of Mojsisovics, who introduced the term Ladinian into literature. 

The name Ladinian was chosen by Bittner after the Ladinian folk of the Southern Alps/Dolomites. At the time, this area was part of the Austrian-Hungarian monarchy with its capital in Vienna. The “Vienna school” of thinking dominated the palaeontology institutions there at the time.

Bittner's introduction of the name Ladinian arose from his recognition of many of the false assumptions of Mojsisovics — assumptions which led to misguided views regarding the ammonoid zones within the Norian timescale well into the 20th century. It was the lovely Tim Tozer who took the time to correct these long lasting errors through his work teasing out the North American Triassic timescale. Tozer used North American, mainly Canadian Triassic ammonoid locations as the basis for his work. Once complete, a correlation with the European Triassic timescale was finally realized.

 

HALLSTATT LIMESTONE AND SALT

Hallstatt Salt Mines, Austria / Permian Salt Diapir

The Hallstatt Limestone is the world's richest Triassic ammonite unit, yielding specimens of more than 500 ammonite species.

Along with diversified cephalopod fauna  — orthoceratids, nautiloids, ammonoids — we also see gastropods, bivalves, especially the late Triassic pteriid bivalve Halobia (the halobiids), brachiopods, crinoids and a few corals. We also see a lovely selection of microfauna represented. 

For microfauna, we see conodonts, foraminifera, sponge spicules, radiolaria, floating crinoids and holothurian sclerites —  polyp-like, soft-bodied invertebrate echinozoans often referred to as sea cucumbers because of their similarities in size, elongate shape, and tough skin over a soft interior. 

Franz von Hauer’s exhaustive 1846 tome describing Hallstatt ammonites inspired renowned Austrian geologist Eduard Suess’s detailed study of the area’s Mesozoic history. That work was instrumental in Suess being the first person to recognize the former existence of the Tethys Sea, which he named in 1893 after the sister of Oceanus, the Greek god of the ocean. As part of the Northern Limestone Alps, the Dachstein rock mass, or Hoher Dachstein, is one of the large karstic mountains of Austria and the second-highest mountain in the Northern Limestone Alps. It borders Upper Austria and Styria in central Austria and is the highest point in each of those states.

Parts of the massif also lie in the state of Salzburg, leading to the mountain being referred to as the Drei-Länder-Berg or three-state mountain. Seen from the north, the Dachstein massif is dominated by the glaciers with the rocky summits rising beyond them. By contrast, to the south, the mountain drops almost vertically to the valley floor. The karst limestones and dolomites were deposited in our Mesozoic seas. The geology of the Dachstein massif is dominated by the Dachstein-Kalk Formation — the Dachstein limestone — which dates back to the Triassic.

Hallstatt and the Hallstatt Sea, Austria

There were several phases of mountain building in this part of the world pushing the limestone deposits 3,000 metres above current sea level. The rock strata were originally deposited horizontally, then shifted, broken up and reshaped by the erosive forces of ice ages and erosion.

The Hallstatt mine exploits a Permian salt diapir that makes up some of this area’s oldest rock. 

The salt accumulated by evaporation in the newly opened, and hence shallow, Hallstatt-Meliata Ocean. This was one of several small ocean basins that formed in what is now Europe during the late Paleozoic and early Mesozoic when the world’s landmasses were welded together to form the supercontinent Pangea. 

Pangea was shaped like a crescent moon that cradled the famous Tethys Sea. Subduction of Tethyian oceanic crust caused several slivers of continental crust to separate from Pangea, forming new “back-arc basins” (small oceans formed by rifting that is associated with nearby subduction) between the supercontinent and the newly rifted ribbon continents.

The Hallstatt-Meliata Ocean was one such back-arc basin. As it continued to expand and deepen during the Triassic, evaporation ceased and reefs flourished; thick limestone deposits accumulated atop the salt. When the Hallstatt-Meliata Ocean closed in the Late Jurassic, the compression squeezed the low-density salt into a diapir that rose buoyantly, injecting itself into the Triassic limestones above.

The Hallstatt salt diapir and its overlying limestone cap came to rest in their present position in the northern Austrian Alps when they were shoved northward as nappes (thrust sheets) during two separate collision events, one in the Cretaceous and one in the Eocene, that created the modern Alps. It is from the Hallstatt salt diapir that Hallstatt, like so many cities and towns, gets its name.

Deposits of rock salt or halite, the mineral name of sodium chloride with the chemical formula of NaCl, are found and mined around the globe. These deposits mark the dried remains of ancient oceans and seas. Names of rivers, towns and cities in Europe — Salzburg, Halle, Hallstatt, Hallein, La Salle, Moselle — all pay homage to their connection to halite and salt production. The Greek word for salt is hals and the Latin is sal. The Turkish name for salt is Tuz, which we see in the naming of Tuzla, a salt-producing region of northeastern Bosnia-Herzegovina and in the names of towns that dot the coast of Turkey where it meets the Black Sea. Hallstatt with its salt diapir is no exception.

The salt-named town of Hallstatt sits on the shores of the idyllic Hallstätter Sea at the base of the Dachstein massif. Visiting it today, you experience a quaint traditional fishing village built in the typical upper Austrian style. Tourism drives the economy as much as salt as this area of the world is picture-perfect from every angle.

Space is at a minimum in the town. For centuries, every ten years the local cemetery exhumes the bones of those buried there and moves them to an ossuary to make room for new burials. The Hallstatt Ossuary is called Karner, Charnel House, or simply Beinhaus (Bone House). Karners are places of secondary burials. They were once common in the Eastern Alps, but that custom has largely disappeared.

Hallstatt Beinhaus Ossuary, Hallstatt, Austria

A collection of over 700 elaborately decorated skulls rest inside the ossuary. They are lined up on rows of wooden shelves that grace the walls of the chapel. Another 500 undecorated skulls, bare and without any kind of adornment, are stacked in the corners.

Each is inscribed and attached to a record with the deceased's name, profession and date of death. The Bone House is located in a chapel in the basement of the Church of Saint Michael. The church dates from the 12th century CE. 

Decorating the skulls was traditionally the job of the local gravedigger and an honour granted to very few. At the family's request, garlands of flowers were painted on the skulls of deceased as decorative crowns if they were female. The skulls of men and boys were painted wreaths of oak or ivy.

Every building in Hallstatt looks out over the Hallstätter Sea. This beautiful mountain lake considered one of the finest of Austria's Salzkammergut region. It lies at the northern foot of the Dachstein mountain range, sitting eight-and-a-half kilometres long and two kilometres wide. The shoreline is dotted by the villages of  Obertraun, Steeg, and Hallstatt.

The region is habitat to a variety of diverse flora and fauna, including many rare species such as native orchids, in the wetlands and moors in the south and north.

Linked by road to the cities of Salzburg and Graz, Hallstatt and its lake were declared one of the World Heritage sites in Austria in 1997 and included in the Hallstatt-Dachstein Salzkammergut Alpine UNESCO World Heritage Site. The little market village of Hallstatt takes its name from the local salt mine.

Hallstatt, Salzkammergut region, Austria

The town is a popular tourist destination with its quaint shops and terraced cafes. In the centre of town, the 19th-century Evangelical Church of Hallstatt with its tall, slender spire is a lakeside landmark. You can see it here in the photo on the left.

Above the town are the Hallstatt Salt mines located within the 1,030-meter-tall Salzburg Salt Mountain. They are accessible by cable car or a three-minute journey aboard the funicular railway. There is also a wonderful Subterranean Salt Lake.

In 1734, there was a corpse found here preserved in salt. The fellow became known as the Man in Salt. Though no archaeological analysis was performed at the time — the mummy was respectfully reburied in the Hallstatt cemetery — based on descriptions in the mine records, archaeologists suspect the miner lived during the Iron Age. This Old Father, Senos ph₂tḗr, 'ɸatīr 'father' may have been a local farmer, metal-worker, or both and chatted with his friends and family in Celtic or Proto-Celtic.

Salt mining in the area dates back to the Neolithic period, from the 8th to 5th Centuries BC. This is around the time that Roman legions were withdrawing from Britain and the Goths sacked Rome. In Austria, agricultural settlements were dotting the landscape and the alpine regions were being explored and settled for their easy access to valuable salt, chert and other raw materials.

The salt-rich mountains of Salzkammergut and the upland valley above Hallstatt were attractive for this reason. The area was once home to the Hallstatt culture, an archaeological group linked to Proto-Celtic and early Celtic people of the Early Iron Age in Europe, c.800–450 BC.

Bronze Age vessel with cow and calf

In the 19th century, a burial site was discovered with 2,000 individuals, many of them buried with Bronze Age artefacts of amber and ivory.

It was this find that helped lend the name Hallstatt to this epoch of human history. The Late Iron Age, between around 800 and 400 BC, became known as the Hallstatt Period.

For its rich history, natural beauty and breathtaking mountainous geology, Hallstatt is a truly irresistible corner of the world.

Salzbergstraße 1, 4830 Hallstatt.  https://www.salzwelten.at/en/home/

Photo: Bronze vessel with cow and calf, Hallstatt by Alice Schumacher - Naturhistorisches Museum Wien - A. Kern – K. Kowarik – A. W. Rausch – H. Reschreiter, Salz-Reich. 7000 Jahre Hallstatt, VPA 2 (Wien, 2008) Seite 133 Abbildung 6. Hallstatt Village & Ossuary Photos: P. McClure Photography ca. 2015.

Bernoulli D, Jenkyns HC (1974) Alpine, Mediterranean, and Central Atlantic Mesozoic facies in relation to the early evolution of the Tethys. Soc Econ Paleont Mineral Spec Publ 19:129–160

Bernoulli D, Jenkyns H (2009) Ancient oceans and continental margins of the Alpine-Mediterranean Tethys: deciphering clues from Mesozoic pelagic sediments and ophiolites. Sedimentology 56:149–190

PAMPHAGOSIRENTIES OF HALLSTATT

 

INDOSPHINCTES OF RUSSIA

Stunning preservation on this lovely microconch of the ammonite, Indosphinctes (Elatmites) aff. submutatus (Nikitin, 1881), from Jurassic, Middle Callovian outcrops of the Kosmoceras jason zone near the Oka River. The exposures are near the city of Elatma in the Ryazan Region of central Russia. 

This specimen is 70 mm at the widest part of the ammonite and is the smaller male form of this species. 

Ryazan Oblast borders Vladimir Oblast (N), Nizhny Novgorod Oblast (NE), the Republic of Mordovia (E), Penza Oblast (SE), Tambov Oblast (S), Lipetsk Oblast (SW), Tula Oblast (W), and Moscow Oblast (NW).

Ryazan Oblast lies in the central part of the Russian Plain between the Central Russian and Volga uplands. The terrain is flat — with the highest point being no more than 300 m above sea level. The soils here are podzolic and boggy on the banks of the Oka. further to the south, they become more fertile with podzolic and leached black earth. This specimen is in the collection of the deeply awesome Emil Black. 

DORSOPLANITES: FROM RUSSIA WITH LOVE

Golden light shines on the ammonite, Dorsoplanites dorsoplanus (Vischniakoff, 1882), Upper Jurassic, Volgian Stage, Panderi Zone. If you wanted to visit this beauty today, she is in the collections of the deeply awesome Emil Black. 

If you wanted to travel to the outcrop where she was found, you would want to head to eastern Europe then search through the rock dumps along the new subway in the city of Moscow along the Moskva River in Central Russia.

Eight biohorizons, four of which were previously distinguished in Central Poland and four new ones have been identified as — contradictionis, pommerania, kuteki, and pilicensis, — were identified in the Dorsoplanites panderi zone of the Upper Jurassic Middle Volgian Substage of the European part of Russia on the basis of the succession of ammonites of the Zaraiskites genus. If that sounds like Greek to you, no worries. Just know that they are actively being studied and those geeking out on the finds are happy as clams.

The peculiarities of variations of the ammonite complexes in space and time testify to the stepwise warming during the Panderi Chron and the occurrence of the significant latitudinal temperature gradient in the Middle Russian Sea. Collection & photo of the awesome Emil Black. 

FREE SCIENCE TEACHER RESOURCES

Hello you! Are you a teacher or student looking for information or images for an educational project? You are more than welcome to use any of the images on this site that have the Fossil Huntress logo on them. The only catch is that they must be for school projects and not be printed more than 500,000 times. 

In the past, I have found finding images that you need to complete a project can be a bit tricky. 

Short of purchasing or borrowing off the internet, teachers and students do not have that many interesting resources available. I have started to include the logo so you can know for sure it is okay to use. If I credit the photo to someone, you would need to ask them first before using it. 

I also post over on the Fossil Huntress Facebook page and will begin putting together teaching sets by album of related content. It is mostly palaeontology, earth history, earth science and natural history. Feel free to use what works best for you. Head on over to Fossil Huntress headquarters at www.fossilhuntress.com for links to all sorts of educational goodness. Good luck!

DECAPODA: CHITIN

Crabs are decapod crustaceans of the Phylum Arthropoda. They inhabit all the world's oceans, sandy beaches, many of our freshwater lakes and streams, and a few prefer to live in forests.

Crabs build their shells from highly mineralized chitin — and chitin gets around. It is the main structural component of the exoskeletons of many of our crustacean and insect friends. Shrimp, crab, and lobster all use it to build their exoskeletons.

Chitin is a polysaccharide — a large molecule made of many smaller monosaccharides or simple sugars, like glucose. It's handy stuff, forming crystalline nanofibrils or whiskers. Chitin is actually the second most abundant polysaccharide after cellulose. It is interesting as we usually think of these molecules in the context of their sugary context but they build many other very useful things in nature — not the least of these are the hard shells or exoskeletons of our crustacean friends.

OH PFEILSCHWANZKREBS!

I was thinking this week about horseshoe crabs. David Appleton shared a lovely trackway earlier this week that may very well record the ancient route of one of these classic living fossils. 

Horseshoe crabs are marine and brackish water arthropods of the order Xiphosura — a slowly evolving, conservative taxa.

Much like (slow) Water Striders (Aquarius remigis), (relatively sluggish) Coelacanth (Latimeria chalumnae) and (the current winner on really slow evolution) Elephant Sharks (Callorhinchus milii), these fellows have a long history in the fossil record with very few anatomical changes. But slow change provides loads of great information. It makes our new friend, Yunnanolimulus luoingensis, an especially interesting and excellent reference point for how this group evolved. We can examine their genome today and make comparisons all the way back to the Middle Triassic (with this new find) and other specimens from further back in the Ordovician.

The evolution of their exoskeleton is well-documented by fossils, but appendage and soft-tissue preservation are extremely rare. A new study analyzes details of the appendage and soft-tissue preservation in Yunnanolimulus luoingensis, a Middle Triassic (ca. 244 million years old) horseshoe crab from Yunnan Province, SW China. The remarkable anatomical preservation includes the chelicerae, five pairs of walking appendages, opisthosomal appendages with book gills, muscles, and fine setae permits comparison with extant horseshoe crabs.

The close anatomical similarity between the Middle Triassic horseshoe crabs and their recent analogues documents anatomical conservatism for over 240 million years, suggesting persistence of lifestyle.

The occurrence of Carcinoscorpius-type claspers on the first and second walking legs in male individuals of Y. luoingensis indicates that simple chelate claspers in males are plesiomorphic for horseshoe crabs, and the bulbous claspers in Tachypleus and Limulus are derived.

As an aside, if you hadn't seen an elephant shark before and were shown a photo, you'd likely say, "that's no freaking shark." You would be wrong, of course, but it would be a very clever observation. Callorhinchus milii look nothing like our Great White friends and they are not true sharks at all. Rather, they are ghost sharks that belong to the subclass Holocephali (chimaera), a group lovingly known as ratfish. They diverged from the shark lineage about 400 million years ago.

If you have a moment, do a search for Callorhinchus milii. The odd-looking fellow with the ironic name, kallos, which means beautiful in Greek, sports black blotches on a pale silver elongate body. And their special feature? It is the fishy equivalent of business in the front, party in the back, with a dangling trunk-like projection at the tip of their snout and well-developed rectal glands near the tail.

As another small point of interest with regards to horseshoe crabs, John McAllister collected several of these while working on his MSc to see if they had microstructures similar to trilobites (they do) and whether their cuticles were likewise calcified. He found no real calcification in their cuticles, in fact, he had a rather frustrating time getting anything measurable to dissolve in acid in his hunt for trace elements. 

Likewise, when looking at oxygen isotopes (16/18) to get a handle on water salinity and temperature, his contacts at the University of Waterloo had tons of fun getting anything at all to analyze. It made for some interesting findings. Sadly, for a number of reasons, he abandoned the work, but you can read his very interesting thesis here: https://dr.library.brocku.ca/handle/10464/1959

Photo: CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=719594

Ref: Hu, Shixue & Zhang, Qiyue & Feldmann, Rodney & Benton, Michael & Schweitzer, Carrie & Huang, Jinyuan & Wen, Wen & Zhou, Changyong & Xie, Tao & Lü, Tao & Hong, Shuigen. (2017). Exceptional appendage and soft-tissue preservation in a Middle Triassic horseshoe crab from SW China. Scientific Reports. 7. 10.1038/s41598-017-13319-x.

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!

WEE BABY EURYPTERID

This adorable wee baby with his teeny aquatic mittens on is a eurypterid from exposures in New York, USA. 

This cutie is one of my favourites. I imagine him wearing mittens but that, of course, is not the case at all.  

This fellow is just under a centimetre in length but his cousins grew larger than a human. Eurypterids were the largest known arthropods to ever live. 

The largest, Jaekelopterus, reached 2.5 meters (8.2 ft) in length — significantly larger than some of his very tiny cousins — most growing to less than 20 centimetres (8 inches) in length. 

More commonly known as sea scorpions, the now-extinct eurypterids were arthropods that lived during the Paleozoic Era. We saw the first of their brethren during the Ordovician and the last of them during the End-Permian Mass Extinction Event. In between, they thrived and irradiated out to every niche within our ancient seas and many later forms survived and thrived in brackish and freshwater. 

The group Arthropoda includes invertebrate animals with exoskeletons, segmented bodies, and paired joint appendages. Eurypterids had six sets of appendages. You can clearly see the segmented body on this cutie, which is one of the defining characteristics of arthropods. The first set was modified into pinchers which are used for feeding. The largest appendage visible in this fossil is a broad paddle that E. tetragonophthalmus used to swim.

This first eurypterid, Eurypterus remipes, was discovered in New York in 1818. It is an iconic fossil for this region and was chosen as the state's official fossil in 1984. An excellent choice as most of the productive eurypterid-bearing outcrops are within the state's boundaries. Most of the fossils we find from them, whether body fossils or trace fossils are from fossil sites in North America and Europe This is because the group lived primarily in the waters around and within the ancient supercontinent of Euramerica. 

Only a handful of eurypterid groups spread beyond the confines of Euramerica and a few genera, such as Adelophthalmus — the longest lived of all known eurypterid genera — and the giant predatory Pterygotus, achieved a cosmopolitan distribution so we find their fossil remains worldwide today. 

Interestingly, the type species, Pterygotus anglicus, was first through to be the remains of a massive fish by Swiss naturalist Louis Agassiz who described it in 1839 — hence the poorly chosen name Pterygotus, which translates to "winged fish. He did catch that embarrassing error five years later, but the name remains and will for all time.

SEA SCORPIONS: PREDATORS OF ANCIENT SEAS

About two dozen families of eurypterids “sea scorpions” are known from the fossil record.

Although these ancient predators have a superficial similarity, including a defensive needle-like spike or telson at their tail end, they are not true scorpions. They are an extinct group of arthropods related to spiders, ticks, mites and other extant creepy crawlies.

Eurypterids hunted fish in the muddy bottoms of warm shallow seas some 460 to 248 million years ago before moving on to hunting grounds in fresh and brackish water during the latter part of their reign. Their numbers diminished greatly during the Permian-Triassic extinction, becoming extinct by 248 million years ago.

Eurypterids are found in Canada, most notably at the Ridgemount Quarry near Niagara Falls. This near-perfect specimen of Eurypterus remipes — held by my cousin Sivert, hand-model extraordinaire — was named the official state fossil of New York in 1984.

EURYPTERUS SEA SCORPIONS

The impressive homeotype specimen of Eurypterus lacustris from Late Silurian deposits in New York. UCMP Berkeley's palaeontological collections.

Eurypterus is by far the most well-studied and well-known eurypterid and its fossil specimens probably represent more than 90% of all known eurypterid specimens.

About two dozen families of eurypterids “sea scorpions” are known from the fossil record. Although these ancient predators have a superficial similarity, including a defensive needle-like spike or telson at their tail end, they are not true scorpions. They are an extinct group of arthropods related to spiders, ticks, mites and other extant creepy crawlies.

The first fossil of Eurypterus was found in 1818 by S. L. Mitchill, a fossil collector. It was recovered from the Bertie Formation of New York, near Westmoreland, Oneida County. Mitchill interpreted the appendages on the carapace as barbels arising from the mouth. He consequently identified the fossil as a catfish of the genus Silurus. In 1825, American zoologist James Ellsworth De Kay identified the fossil correctly as an arthropod. He named it Eurypterus remipes and established the genus Eurypterus in the process. The name means "wide wing" or "broad paddle", referring to the swimming legs, from Greek εὐρύς (eurús, wide) and πτερόν (pteron, wing).

However, De Kay thought Eurypterus belonged to branchiopods, a group of crustaceans that includes water fleas. Soon after, Eurypterus lacustris was also discovered in New York in 1835 by the palaeontologist Richard Harlan. Another species was discovered in Estonia in 1858 by Jan Nieszkowski. He considered it to be of the same species as the first discovery (E. remipes); though it has since been renamed Eurypterus tetragonophthalmus.

Jan Nieszkowski's 1858 dissertation

These specimens from Estonia are often of extraordinary quality, retaining the actual cuticle of their exoskeletons. In 1898, the Swedish palaeontologist Gerhard Holm separated these fossils from the bedrock with acids. Holm was then able to examine the almost perfectly preserved fragments under a microscope. His remarkable study led to the modern breakthrough in eurypterid morphology.

More fossils were recovered in great abundance in New York in the 19th century, and elsewhere in eastern Eurasia and North America. Today, Eurypterus remains one of the most commonly found and best-known eurypterid genera, comprising more than 95% of all known eurypterid fossils.

Eurypterids hunted fish in the muddy bottoms of warm shallow seas some 460 to 248 million years ago before moving on to hunting grounds in fresh and brackish water during the latter part of their reign. Their numbers diminished greatly during the Permian-Triassic extinction, becoming extinct by 248 million years ago.

Image: Dorsal and ventral aspects of Eurypterus tetragonophthalmus, from Jan Nieszkowski's 1858 dissertation; By Jan Nieszkowski (1833-1866) - Nieszkowski J. De euryptero remipede: dissertatio inauguralis. Dorpat: H. Laakmann, 1858, Public Domain, https://commons.wikimedia.org/w/index.php?curid=11225856

HADROSAUR TOOTH FROM ALBERTA

A rare and very beautifully preserved Cretaceous Hadrosaur Tooth. This lovely specimen is from one of our beloved herbivorous "Duck-Billed" dinosaurs from 68 million-year-old outcrops near Drumheller, Alberta, Canada, and is likely from an Edmontosaurus.

When you scour the badlands of southern Alberta, most of the dinosaur material you'll find are from hadrosaurs. These lovely tree-less valleys make for excellent-searching grounds and have led us to know more about hadrosaur anatomy, evolution, and paleobiology than for most other dinosaurs.

We have oodles of very tasty specimens and data to work with. We've got great skin impressions and scale patterns from at least ten species and interesting pathological specimens that provide valuable insights into hadrosaur behaviour. Locally, we have an excellent specimen you can visit in the Courtenay and District Museum on Vancouver Island, Canada. The first hadrosaur bones were found on Vancouver Island a few years back by Mike Trask, VIPS, on the Trent River near Courtenay.

The Courtenay hadrosaur is a first in British Columbia, but our sister province of Alberta has them en masse. Given the ideal collecting grounds, many of the papers on hadrosaurs focus on our Canadian finds. These herbivorous beauties are also found in Europe, South America, Mexico, Mongolia, China, and Russia. Hadrosaurs had teeth arranged in stacks designed for grinding and crushing, similar to how you might picture a cow munching away on the grass in a field. These complex rows of "dental batteries" contained up to 300 individual teeth in each jaw ramus. But even with this great number, we rarely see them as individual specimens.

They didn't appear to shed them all that often. Older teeth that are normally shed in our general understanding of vertebrate dentition, were resorped, meaning that their wee osteoclasts broke down the tooth tissue and reabsorbed the yummy minerals and calcium.

As the deeply awesome Mike Boyd notes, "this is an especially lucky find as hadrosaurs did not normally shed so much as a tooth, except as the result of an accident when feeding or after death. Typically, these fascinating dinosaurs ground away their teeth... almost to nothing."

In hadrosaurs, the root of the tooth formed part of the grinding surface as opposed to a crown covering over the core of the tooth. And curiously, they developed this dental arrangement from their embryonic state, through to hatchling then full adult.

There's some great research being done by Aaron LeBlanc, Robert R. Reisz, David C. Evans and Alida M. Bailleul. They published in BMC Evolutionary Biology on work that looks at the histology of hadrosaurid teeth analyzing them through cross-sections. Jon Tennant did a nice summary of their research. I've included both a link to the original journal article and Jon Tennant's blog below.

LeBlanc et al. are one of the first teams to look at the development of the tissues making up hadrosaur teeth, analyzing the tissue and growth series (like rings of a tree) to see just how these complex tooth batteries formed.

They undertook the first comprehensive, tissue-level study of dental ontogeny in hadrosaurids using several intact maxillary and dentary batteries and compared them to sections of other archosaurs and mammals. They used these comparisons to pinpoint shifts in the ancestral reptilian pattern of tooth ontogeny that allowed hadrosaurids to form complex dental batteries.

References:

LeBlanc et al. (2016) Ontogeny reveals function and evolution of the hadrosaurid dinosaur dental battery, BMC Evolutionary Biology. 16:152, DOI 10.1186/s12862-016-0721-1 (OA link)

To read more from Jon Tennant, visit: https://blogs.plos.org/paleocomm/2016/09/14/all-the-better-to-chew-you-with-my-dear/

Photo credit: Derrick Kersey. For more awesome fossil photos like this from Derrick, visit his page: https://www.facebook.com/prehistoricexpedition/

CASTLE PEAK: JET RANGER

If you look closely, you can see a wee jet ranger helicopter hovering over a very chilly Castle Peak in the southern Chilcotin Range, British Columbia, Canada. 

Castle Peak was our glorious landmark and loadstone of basalt that marked the spot on our Jurassic/Triassic palaeo adventures collecting about 7000 ft. The peak itself reaches higher still to around 8,176 ft.

The late Hettangian ammonite fauna from Taseko Lakes is diverse and relatively well‐preserved. Over three field seasons from 2001-2003, thirty-five taxa from the Mineralense and Rursicostatum zones were studied and three new species discovered and named: Fergusonites hendersonae, Eolytoceras constrictum and Pseudaetomoceras victoriense. This material is very important as it greatly expands our understanding of the fauna and ranges of ammonites currently included in the North American regional ammonite zonation. 

I had the very great honour of having the newly named, Fergusonites hendersonae, a new species of nektonic carnivorous ammonite, named after me by palaeontologist Louse Longridge from the University of British Columbia. 

I had met Louise as an undergrad and was pleased as punch to hear that she would be continuing the research by Dr. Howard Tipper, the authority on this area of the Chilcotins and Haida Gwaii — which he dearly loved. 

"Tip" was a renowned Jurassic ammonite palaeontologist and an excellent regional mapper who mapped large areas of the Cordillera. He made significant contributions to Jurassic paleobiogeography and taxonomy in collaboration with Dr. Paul Smith, Head of Earth and Ocean Science at the University of British Columbia. 

Tip’s regional mapping within BC has withstood the test of time and for many areas became the regions' base maps for future studies. The scope of Tip’s understanding of Cordilleran geology and Jurassic palaeontology will likely never be matched. He passed away on April 21, 2005. His humour, knowledge and leadership will be sorely missed. 

Before he left us, he shared that knowledge with many of whom would help to secure his legacy for future generations. We did several trips over the years up to the Taseko Lake area of the Rockies joined by many wonderful researchers from Vancouver Island Palaeontological Society and Vancouver Paleontological Society, as well as the University of British Columbia. Both Dan Bowen and John Fam were instrumental in planning those expeditions and each of them benefited greatly from the knowledge of Dr. Howard Tipper. 

If not for Tipper's early work in the region, our shared understanding and much of what was accomplished in his last years and after his passing would not have been possible. 

Over the course of three field seasons, we endured elevation sickness, rain, snow, grizzly bears and very chilly nights  — we were sleeping right next to a glacier at one point — but were rewarded by the enthusiastic crew, helicopter rides — which really cut down the hiking time — excellent specimens including three new species of ammonites, along with a high-spired gastropod and lobster claw that have yet to be written up. This area of the world is wonderful to hike and explore — a stunningly beautiful country. We were also blessed with access as the area is closed to all fossil collecting except with a permit.

LATE HETTANGIAN TO EARLY SINEMURIAN FAUNA OF NEVADA

Hiking the hills of Nevada looking for David Taylor's faunal succession based on ammonoids established for the Late Hettangian to Early Sinemurian interval in the Western Cordillera.

The land here is free of trees with low only low groupings of gnarly scrub to work through to get to the bedrock below. 

Our work here was in October, which is a time when Nevada is cool in the mornings and evenings, but still surprisingly hot during the day. It is also tarantula breeding season and my first glimpse of these spiders in volume at field sites. 

It was a tremendous experience to walk through time and compare the fossil assemblages here with our own in the Canadian Rockies. Here the faunal sequence consists of one zone and four informal biochronologic units or assemblages and was outlined by Taylor as follows: Paracaloceras morganense assemblage, Badouxia oregonensis assemblage, Canadensis Zone, Metophioceras trigonatum assemblage and Coroniceras involutum. They matched up to specimens we collected over three field seasons to similar faunal outcrops of Late Hettangian to Early Sinemurian of the Last Creek and Tyaughton area of the Canadian Rockies.

The succession also correlates with the interval delineated by the Northwest European Angulata Zone through the Lyra Subzone. Two new genera (Guexiceras and Tipperoceras) are described along with 23 new species. 

The phylogenetic relationships of the earliest Jurassic ammonite superfamilies indicate that it is useful to include under the Psiloceratida, the Psilocerataceae and their derivatives including the Lytocerataceae. 

The Arietitaceae were derived from Hettangian Lytocerataceans. There is still much work to be done to work out the finer points of comparison between British Columbia's Triassic fauna and those that lived and died in what is now Nevada, USA, but enjoyable work it it.

TRACKING THROUGH THE TRIASSIC

Grambergia sp. Middle Triassic Ammonoid of  BC, Canada

In the early 1980s, Tim Tozer, Geological Survey of Canada was looking at the spread of marine invertebrate fauna in the Triassic of North America. 

In the western terranes of the Cordillera, marine faunas from southern Alaska and Yukon to Mexico are known from the parts that are obviously allochthonous with regard to the North American plates.

Lower and upper Triassic faunas of these areas, as well as some that are today up to 63 ° North, have the characteristics of the lower palaeo latitudes. In the western Cordillera, these faunas of the lower paleo latitudes can be found up to 3,000 km north of their counterparts on the American plate. This indicates a tectonic shift of significant magnitude. There are marine triads on the North American plate over 46 latitudes from California to Ellesmere Island. 

For some periods, two to three different faunal provinces can be distinguished. The differences in faunal species are linked, not surprisingly, to their palaeolatitude. They are called LPL, MPL, HPL (lower, middle, higher palaeolatitude).

Nevada provides the diagnostic features of the lower (LPL); northeastern British Columbia that of the middle (MPL) and Sverdrup Basin, the large igneous province on Axel Heiberg Island and Ellesmere Island, Nunavut, Canada near the rifted margin of the Arctic Ocean, that of the higher palaeolatitude (HPL).

A distinction between the provinces of the middle and the higher palaeo-situations can not be made for the lower Triassic and lower Middle Triassic (anise). However, all three provinces can be seen in the deposits of Ladin, Kam and Nor.

In the early 2000s, as part of a series of joint UBC, VIPS and VanPS fossil field trips (and then Chair of the VanPS), I explored much of the lower faunal outcrops of northeastern British Columbia. It was my first time seeing many of British Columbia's Triassic outcrops. Years later, and fueled by seeing paper after paper correlating the faunal assemblages of BC to those of Nevada, I had the very great pleasure of walking through the Nevada strata with John Fam (VanPS, Vice-Chair), Dan Bowen (VIPS, Chair) and Betty Franklin (VIPS, Goddess of Everything and BCPA, Treasurer) — and witnessing first-hand the correlation between the Nevada fauna and those from the Triassic of British Columbia, Canada.

Triassic ammonoids, West Humboldt Mountains, Nevada, USA

The Nevada faunal assemblages are a lovely match. The quality of preservation at localities like Fossil Hill in the Humboldt Mountains of Nevada, perhaps the most famous and important locality for the Middle Triassic (Anisian/Ladinian) of North America, is truly outstanding.

Aside from sheer beauty and spectacular preservation, the ammonoids and belemnites were tucked in cozily with very well preserved ichthyosaur remains.

Tozer's interest in our marine invert friends was their distribution. How and when did certain species migrate, cluster, evolve — and for those that were prolific, how could their occurrence — and therefore significance — aide in an assessment of plate and terrane movements that would help us to determine paleolatitudinal significance. I share a similar interest but not exclusive to our cephalopod fauna. The faunal collection of all of the invertebrates holds appeal.

Middle Triassic (Anisian/Ladinian) Fauna

This broader group held an interest for J.P. Smith who published on the marine fauna in the early 1900s based on his collecting in scree and outcrops of the West Humboldt Mountains, Nevada. He published his first monograph on North American Middle Triassic marine invertebrate fauna in 1914.

N. J. Siberling from the US Geological Survey published on these same Nevada outcrops in 1962. His work included nearly a dozen successive ammonite faunas, many of which were variants on previously described species. Both their works would inform what would become a lifelong piecing together of the Triassic puzzle for Tozer.

If one looks at the fauna and the type of sediment, the paleogeography of the Triassic can be interpreted as follows: a tectonically calm west coast of the North American plate that bordered on an open sea; in the area far from the coast, a series of volcanic archipelagos delivered sediment to the adjacent basins. Some were lined or temporarily covered with coral wadding and carbonate banks. Deeper pools were in between. The islands were probably within 30 degrees of the triadic equator. They moved away from the coast up to about 5000 km from the forerunner of the East Pacific Ridge. The geographical situation west of the back was probably similar.

Jurassic and later generations of the crust from near the back have brought some of the islands to the North American plate; some likely to South America; others have drifted west, to Asia. There are indications that New Guinea, New Caledonia and New Zealand were at a northern latitude of 30 ° or more during the Triassic period.

The terranes that now form the western Cordillera were probably welded together and reached the North American plate before the end of the Jurassic period.

Marine Triassic occurs on the North American Plate over a latitudinal spread of 46 degrees, from California to Ellesmere Island. At some intervals of time faunas on the Plate permit the discrimination of two or three provinces with distinctively different coeval faunas. The faunal differences are evidently related to paleolatitude and the provinces are designated LPL, MPL, HPL (low, mid, high paleolatitude). Nevada provides the diagnostic characters of the LPL province; northeastern British Columbia the MPL; the Sverdrup Basin the HPL. In the Lower Triassic and early Middle Triassic (Anisian), the distinction between the MPL and HPL provinces cannot be made. All three provinces are recognized in the Ladinian, Carnian and Norian deposits.

Juvavites sp. Geological Survey of Canada. Photo: John Fam

In the western tracts of the Cordillera, the part formed of suspect terranes, apparently allochthonous with respect to the North American Plate, marine faunas are known all the way from southern Alaska and Yukon to Mexico.

Lower and Upper Triassic faunas from these terranes, including some which today are at 63 degrees north, have the characters of the LPL province.

Middle Triassic faunas from the terranes, as presently known, do not contribute significant data. In the terranes of the Western Cordillera, LPL faunas were now up to 3,000 km north of their counterparts on the American Plate. Through the fossil fauna assemblages, we can see this level of tectonic displacement.

Taking into account the faunas and the nature of the rocks, the Triassic paleogeography is interpreted as a tectonically quiet west shore for the North American Plate, bordered by an open sea or ocean; then, well off-shore, a series of volcanic archipelagos shedding sediment into adjacent basins. Some were fringed or intermittently covered by coralline shoals and carbonate banks. Deeper basins were in between. The islands probably were within 30 degrees of the Triassic equator and extended offshore for about 5000 km, to the spreading ridge directly ancestral to the East Pacific Rise. The geography west of the spreading ridge was probably comparable.

Jurassic and later generation of crust at the ridge had driven some of the islands into the North American Plate; some probably to South America; others have gone west to Asia. Evidence is given that northern New Guinea, New Caledonia and New Zealand may have been at a north latitude of 30 degrees or more in the Triassic. The terranes now forming the Western Cordillera had probably amalgamated, and reached the North American Plate, before the end of the Jurassic.

At the end of the Rhaetian (part of the Triassic period), most of the ammonites had died out. The Hettangian, a rather poorly understood 3 million year time interval followed the Triassic-Jurassic mass extinction event.

During the Hettangian, the new or  Neoammonites developed quite quickly. Within a million years, a fairly large, diverse selection of genera and species had risen to fill the void. The gap created by the Triassic-Jurassic extinction event was re-filled and our ability to "read the rocks' to understand their continued movement through tectonic plate shifting recommenced.

Alsatites proaries, Hettangian Ammonite

It is during the Hettangian that the smooth shelled ammonite genus Psiloceras first appears. They span the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). For my European friends, the Hettangian is the time span in which the marine limestone, shales and clay Lias of western Europe were deposited.

This Hettangian ammonite, Alsatites proaries, is a lovely example of the cephalopods cruising our ancient oceans at that time. Alsatites is an extinct genus of cephalopod belonging to the Ammonite subclass. They lived during the Early Jurassic, Hettangian till the Sinemurian and are generally extremely evolute, many whorled with a broad keel. Or, as described by one of my very young friends, he looks like a coiled snake you make in pottery class.

The Hettangian is an interesting little period of our history. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). For my European friends, the Hettangian is the time in which the marine limestone, shales and clay Lias of western Europe were deposited. In British Columbia, Canada, we see the most diverse middle and late Hettangian (Early Jurassic) ammonite assemblages in the Queen Charlotte Islands (Haida Gwaii), an archipelago about 50 km off British Columbia's northern Pacific coast. In total, 53 ammonite taxa are described of which Paradasyceras carteri, Franziceras kennecottense, Pleuroacanthites charlottensis, Ectocentrites pacificus and Curviceras haidae are new.

In general, North American Early Jurassic ammonites are of Tethyan affinity or endemic to the eastern Pacific. For this reason, a separate zonation for the Hettangian and Sinemurian of the Western Cordillera of North America was established. Taylor et al. (2001), wrote up and published on much of this early research though, at the time, very little Canadian information was included.

Longridge, L. M., et al. “Three New Species of the Hettangian (Early Jurassic) Ammonite Sunrisites from British Columbia, Canada.” Journal of Paleontology, vol. 82, no. 1, 2008, pp. 128–139. JSTOR, www.jstor.org/stable/20144175. Accessed 27 Jan. 2020.

Tozer, ET (Tim): Marine Triassic faunas of North America: Their significance for assessing plate and terrane movements. Geol Rundsch 71, 1077-1104 (1982). https://doi.org/10.1007/BF01821119

Danner, W. (Ted): Limestone resources of southwestern British Columbia. Montana Bur. Mines & Geol., Special publ. 74: 171-185, 1976.

Davis, G., Monger, JWH & Burchfiel, BC: Mesozoic construction of the Cordilleran “collage”, central British Columbia to central California. Pacific Coast Paleography symposium 2, Soc. Economic Paleontologists and Mineralogists, Los Angeles: 1-32, 1978.

Gibson, DW: Triassic rocks of the Rocky Mountain foothills and front ranges of northeastern British Columbia and west-central Alberta. Geol. Surv. Canada Bull. 247, 1975.

Photo of the large belemnite (Atractites sp?) and ammonites (Sunrisites & Badouxia) from the Lower Jurassic (Late Hettangian), Last Creek Formation (Castle Pass member), Taseko Lakes area, British Columbia, Canada in the collection of the deeply awesome John Fam.

Photo: A drawer of Juvavites sp. in the collections of the Geological Survey of Canada. These rarely seen Upper Triassic (Carnian to Norian) ammonoids were collected over many decades by geologists of the Geological Survey of Canada from Northeastern British Columbia. Photo care of the deeply awesome John Fam.

Photo: Grambergia sp. from the Early Anisian (Middle Triassic) ammonoid biostratigraphy of northeastern British Columbia, Canada. Collection of Fossil Huntress.

Photo: Alsatites proaries, Coll. Reiter, Neoammoniten, 30 July 2011, 19:26:10

NEVADA: AMMONOIDS AND CONODONTS

Nevada is a wonderful place to explore our palaeontological history. The state spans a broad spectrum of exposures showcasing the depth of geologic time. It is an interesting cross-section of young and old — and interestingly, a lovely comparison to the Triassic outcrops in British Columbia.

Exposures of the Upper Triassic, Early Norian, Kerri zone, Luning formation, West Union Canyon, just outside Berlin-Ichthyosaur State Park, Nevada.

The Berlin-Ichthyosaur State Park in central Nevada is a very important locality for the understanding of the Carnian-Norian boundary (CNB) in North America.

Rich ammonoid faunas from this site within the Luning Formation were studied by Silberling (1959) and provided support for the definition of the Schucherti and Macrolobatus zones of the latest Carnian, which are here overlain by well-preserved faunas of the earliest Norian Kerri Zone. Despite its importance, no further investigations have been done at this site during the last 50 years.

Jim Haggart, Mike Orchard and Paul Smith collaborated on a project that took them down to Nevada to look at the conodonts and ammonoids; the group then published a paper, "Towards the definition of the Carnian/Norian Boundary: New data on Ammonoids and Conodonts from central Nevada," which you can find in the proceedings of the 21st Canadian Paleontology Conference; by Haggart, J W (ed.); Smith, P L (ed.); Canadian Paleontology Conference Proceedings no. 9, 2011 p. 9-10.

They conducted a bed-by-bed sampling of ammonoids and conodonts in West Union Canyon during October 2010. The eastern side of the canyon provides the best record of the Macrolobatus Zone, which is represented by several beds yielding ammonoids of the Tropites group, together with Anatropites div. sp. conodont faunas from both these and higher beds are dominated by ornate 'metapolygnthids' that would formerly have been collectively referred to Metapolygnathus primitius, a species long known to straddle the CNB. Within this lower part of the section, they resemble forms that have been separated as Metapolygnathus mersinensis. Slightly higher, forms close to 'Epigondolella' orchardi and a single 'Orchardella' n. sp. occur. This association can be correlated with the latest Carnian in British Columbia.

Ammonoids of the Luning Formation

Higher in the section, the ammonoid fauna shows a sudden change and is dominated by Tropithisbites. Few tens of metres above, but slightly below the first occurrence of Norian ammonoids Guembelites jandianus and Stikinoceras, two new species of conodonts (Gen et sp. nov. A and B) appear that also occur close to the favoured Carnian/Norian boundary at Black Bear Ridge, British Columbia. Stratigraphically higher collections continue to be dominated by forms close to M. mersinensis and 'E.' orchardi.

The best exposure of the Kerri Zone is on the western side of the West Union Canyon. Ammonoids, dominated by Guembelites and Stikinoceras div. sp., have been collected from several fossil-bearing levels. Conodont faunas replicate those of the east section. The collected ammonoids fit perfectly well with the faunas described by Silberling in 1959, but they differ somewhat from the coeval faunas of the Tethys and Canada.

The genus Gonionotites, very common in the Tethys and British Columbia, is for the moment unknown in Nevada. More in general, the Upper Carnian faunas are dominated by Tropitidae, while Juvavitidae are lacking.

After years of reading about the correlation between British Columbia and Nevada, I had the very great pleasure of walking through these same sections in October 2019 with members of the Vancouver Paleontological Society and Vancouver Island Palaeontological Society. It was with that same crew that I had originally explored fossil sites in the Canadian Rockies in the early 2000s. Those early trips led to paper after paper and the exciting revelations that inspired our Nevada adventure.

LOWER PLIENSBACHIAN: ANDROGYNOCERAS

This gorgeous Lower Pliensbachian macroconch of the ammonite Androgynoceras lataecosta was found as a nodule from the Green Ammonite beds, Lower Pliensbachian, Stonebarrow Marl Member, Charmouth Mudstone Formation (190 MYA) at Charmouth Beach, Dorset Coast in the summer of 2020. 

This specimen was found, prepped and photographed by the lovely and talented folk at Stonebarrow Fossils. 

And what a delightful surprise! The large macroconch specimen here is 12 cm but is cuddled in with her is a lovely grouping of  the diminutive male microconchs of Androgynoceras (Hyatt, 1867) if you are lucky — sometimes a Tragophylloceras loscombi (Sowerby, 1814) — or nothing at all if you are not. 

We see a great variation in this species and the ammonite species that make up this population. Murray Edmunds from Chipping Norton, UK shared some of his insights on why we see such variation and how a phylogenetic species concept may be masking a continuum that tells a very different story.  

We are starting to recognise that these could all be variants of one interbreeding population — with a highly variable duration of a juvenile Capricorn stage. Palaeontologists use a phylogenetic species concept as you cannot test reproductive isolation in any but the most recent of fossils.

By definition, individuals within an interbreeding population cannot belong to different species, let alone different genera. In palaeontology, we can only interpret what we see with reference to what we understand of biology. 

In the Davoei Zone Liparoceratidae, we have a single lineage that evolves into Oistoceras. The microconchs (putative males) are small Capricorns, and the macroconchs (putative females) are very variable: they have a Capricorn juvenile stage that can be expressed for only a few mm (or not at all), or for many cm. But eventually, the adult macroconch body chamber acquires liparoceratid ornament — inflated and bipinnate with numerous secondary ribs. 

Unfortunately, the green ammonite beds at Charmouth preserve only juvenile macroconchs so we do not get to appreciate the similarity and differences of the mature adult shell form. These beauties can look very different from one another but are all the same species. 

Historically, this difference in appearance led to all the individuals — both micro and macroconchs — with prolonged Capricorn morphology being assigned to Androgynoceras and those macroconchs lacking the juvenile Capricorn stage (as is typical in their Ibex zone ancestors) to be Liparoceras. 

Different species were named for different variants. But this is a purely morphological approach to nomenclature and does not reflect the taxonomy used for extant organisms where we try to reflect phylogeny.

But as more and more examples are collected, we start to see that these specimens form a continuum. And as we follow them up through time, we see that all of them (microconchs and macroconchs, regardless of the extent of the Capricorn stage — although that tends to become more prolonged through time — simultaneously evolve progressively forwardly projected ribs across the venter, culminating in Oistoceras. 

This simultaneous evolutionary change across the entire Liparoceratid population more or less proves that we have a single interbreeding clade. And that it is separate from Becheiceras – through that’s another story! And they all go extinct simultaneously too, whereas Becheiceras carries on into the Margaritatus Zone. If you're a grad student looking to do your thesis, there is a very interesting story you could tell.

If you fancy a web stroll through some beautifully prepped specimens from Jurassic Coast, UK, or if you'd like to get some prepped, you can check out Stonebarrow Fossils here: https://www.stonebarrowfossils.co.uk/  / Photos: Stonebarrow Fossils

If you like podcasts, check out the Fossil Huntress — Palaeo Sommelier Podcast at https://anchor.fm/fossil-huntress / Spotify / Google Play / Apple Podcasts