THE LURE OF THE SEA

Our dear penguins, seals, sea lions, walruses, whales, crocodiles and sea turtles were once entirely terrestrial. Yes, they lived mostly or entirely on land. 

Many of these once land-dwelling animals returned to the sea throughout evolutionary history. We have beautifully documented cases from amphibians, reptiles, birds and mammals from over 30 different lineages over the past 250 million years.

Some dipped a toe or two into freshwater ponds, but make no mistake, they were terrestrial. Each of these animals had ancestors that tried out the sea and decided to stay. They evolved and employed a variety of adaptations to meet their new saltwater challenges. Some adapted legs as fins, others became more streamlined, and still, others developed specialized organs to extract dissolved oxygen from the water through their skin or gills. The permutations are endless.

Returning to the sea comes with a whole host of benefits but some serious challenges as well. Life at sea is very different from life on land. Water is denser than air, impacting how an animal moves, sees and hears. More importantly, it impacts an air-breathing animal's movement on a pretty frequent basis. If you need air and haven't evolved gills, you need to surface frequently. Keeping your body temperature at a homeostatic level is also a challenge as water conducts heat much better than air. Even with all of these challenges, the lure of additional food sources and freedom of movement kept those who tried the sea in the sea and they evolved accordingly.

Most major animal groups appear for the first time in the fossil record half a billion years ago. We call this flourishing of species the Cambrian Explosion. While this was a hugely intense period of species radiation, the evolutionary origins of animals are likely to be significantly older. About 700 million years ago the Earth was covered in ice and snow. This was an ice age so intense we refer to this time in our ancient history as Snowball Earth. Once that ice receded, it exposed rocks that contained a variety of weird and wonderful fossils that speak to ancient animals that are only now being studied.

Dr Frankie Dunn, a palaeontologist and an Early Career Research Fellow at the Oxford University Museum of Natural History and Merton College is one of the folks who are examining this early history of some of our first animals. Her research focuses on the origin and early evolution of animals and particularly on the fossil record of the late Ediacaran Period (570 – 540 million years ago).  Dr Dunn's research is exploring ancient species like the long-extinct Rangeomorpha to help understand how animal body plans evolved in deep time well before the divergence of the extant (living) animal lineages.

VERTEBRATES AND INVERTEBRATES

You and I are vertebrates, we have backbones. Having a backbone or spinal column is what sets apart you, me and almost 70,000 species on this big blue planet.

So, which lucky ducks evolved one? Well, ducks for one. Warm-blooded birds and mammals cheerfully claim those bragging rights. They're joined by our cold-blooded, ectothermic friends, the fish, amphibians and reptiles. All these diverse lovelies share this characteristic.

And whether they now live at sea or on land, all of these lineages evolved from a marine organism somewhere down the line, then went on to develop a notochord and spinal column. Notochords are flexible rods that run down the length of chordates and vertebrates. They are handy adaptations for muscle attachment, helping with signalling and coordinating the development of the embryonic stage. The cells from the notochord play a key role in the development of the central nervous system and the formation of motor neurons and sensory cells. Alas, we often take our evolution for granted.

Let's take a moment to appreciate just how marvellous this evolutionary gift is and what it allows us to do. Your backbone gives your body structure, holds up that heavy skull of yours and connects your tasty brain to your body and organs. Eating, walking, fishing, hunting, your morning yoga class, are all made possible because of this adaptation. Pick pretty near anything you love to do and it is only possible because of your blessed spine.

And it sets us apart from our invertebrate friends.

While seventy thousand may seem like a large number, it represents less than three to five per cent of all described animal species. The rest is made up of the whopping 97%'ers, our dear invertebrates who include the arthropods (insects, arachnids, crustaceans, and myriapods), molluscs (our dear chitons, snails, bivalves, squid, and octopus), annelids (the often misunderstood earthworms and leeches), and cnidarians (our beautiful hydras, jellyfish, sea anemones, and corals). 

You will have noticed that many of our invertebrate friends occur as tasty snacks. Having a backbone provides a supreme advantage to your placement in the food chain. Not always, as you may include fish and game on your menu. But generally, having a backbone means you're more likely to be holding the menu versus being listed as an appetizer. So, enjoy your Sunday 'downward dog' and thank your backbone for the magical gift it is.

FRACTAL BUILDING: AMMONITES

Argonauticeras besairei, Collection of  José Juárez Ruiz.

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

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

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

Catching a fish with your hands is no easy feat, as I'm sure you know. But the Ammonites were skilled and successful hunters. They caught their prey while swimming and floating in the water column. Within their shells, they had a number of chambers, called septa, filled with gas or fluid that were interconnected by a wee air tube. By pushing air in or out, they were able to control their buoyancy in the water column.

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

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

The Ammonoidea can be divided into six orders:

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

Ammonites have intricate and complex patterns on their shells called sutures. The suture patterns differ across species and tell us what time period the ammonite is from. If they are geometric with numerous undivided lobes and saddles and eight lobes around the conch, we refer to their pattern as goniatitic, a characteristic of Paleozoic ammonites.

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

Hoplites bennettiana (Sowby, 1826).

If they have lobes and saddles that are fluted, with rounded subdivisions instead of saw-toothed, they are likely Jurassic or Cretaceous. If you'd like to see a particularly beautiful Lower Jurassic ammonite, take a peek at Apodoceras. Wonderful ridging in that species.

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

At the time that this fellow was swimming in our oceans, ankylosaurs were strolling about Mongolia and stomping through the foliage in Utah, Kansas and Texas. Bony fish were swimming over what would become the strata making up Canada, the Czech Republic and Australia. Cartilaginous fish were prowling the western interior seaway of North America and a strange extinct herbivorous mammal, Eobaatar, was snuffling through Mongolia, Spain and England.

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

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

They were prolific breeders that evolved rapidly. If you could cast a fishing line into our ancient seas, it is likely that you would hook an ammonite, not a fish. They were prolific back in the day, living (and sometimes dying) in schools in oceans around the globe. We find ammonite fossils (and plenty of them) in sedimentary rock from all over the world.

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

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

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

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

GORGONS OF THE GREAT KAROO

Gorgons or Gorgonopsia were sabre-toothed therapsids who roamed our ancient Earth from the Middle to Upper Permian — 265 to 252 million years ago — with their long claws, lizard eyes and massive canines. 

I learned about the Karoo, and indeed the Gorgons, by a book of the same name by the deeply awesome Peter Ward. His introduction to what life and fieldwork are like in the arid, inhospitable ancestral home of the Gorgons in South Africa made me laugh out loud. It is a highly enjoyable read. The Great Karoo was formed in a vast inland basin 320 million years ago, at a time when the part of Gondwana which would eventually become Africa lay over the South Pole. 

The Karoo records a wonderful time in our evolutionary history when the world was inhabited by interesting amphibians and mammal-like reptiles — including the apex predators of the day, the Gorgons.

The link below will take you to the Fossil Huntress Podcast where you can travel back in time to visit the Great Karoo with me. Here's the link: https://anchor.fm/.../The-Great-Karoo-of-South-Africa...

Photo: National Geographic Society

ACANTHOHOPLITES BIGOURETI

A very pleasing example of the Ammonite Acanthohoplites bigoureti (Seunes, 1887). Lower Cretaceous, Upper Aptian, from a riverbed concretion, Kurdzhips River, North Caucasus Mountains, Republic of Adygea, Russia. 

Geologically, the Caucasus Mountains belong to a system that extends from southeastern Europe into Asia and is considered a border between them. The Greater Caucasus Mountains are mainly composed of Cretaceous and Jurassic rocks with the Paleozoic and Precambrian rocks in the higher regions. 

Some volcanic formations are found throughout the range. On the other hand, the Lesser Caucasus Mountains are formed predominantly of the Paleogene rocks with a much smaller portion of the Jurassic and Cretaceous rocks. 

The evolution of the Caucasus began from the Late Triassic to the Late Jurassic during the Cimmerian orogeny at the active margin of the Tethys Ocean while the uplift of the Greater Caucasus is dated to the Miocene during the Alpine orogeny.

The Caucasus Mountains formed largely as the result of a tectonic plate collision between the Arabian plate moving northwards with respect to the Eurasian plate. As the Tethys Sea was closed and the Arabian Plate collided with the Iranian Plate and was pushed against it and with the clockwise movement of the Eurasian Plate towards the Iranian Plate and their final collision, the Iranian Plate was pressed against the Eurasian Plate. 

As this happened, the rocks that had been deposited in this basin from the Jurassic to the Miocene were folded to form the Greater Caucasus Mountains. This collision also caused the uplift and the Cenozoic volcanic activity in the Lesser Caucasus Mountains.

The preservation of this Russian specimen is outstanding. Acanthohoplites bigoureti are also found in Madagascar, Mozambique, in the Rhone-Alps of France and the Western High Atlas Mountains and near Marrakech in Morocco. This specimen measures 55mm and is in the collection of the deeply awesome Emil Black.

ANAHOPLITES PLANUS OF FRANCE

A beautiful specimen of the ammonite, Anahoplites planus (Mantell, 1822) from Albian deposits in Villemoyenne Quarry, Courcelles, Aube, north-central France. Anahoplites (Hyatt, 1900) is a genus of compressed hoplitid ammonites with flat sides, narrow, flat or grooved venters, and flexious ribs or striae arising from weak umbilical tubercles that end in fine dense ventrolateral nodes.

This lovely has attracted some roommates — an oyster, some bryozoans and worm tubes are attached to her shell.

Anahoplites is now included in the subfamily Anahoplitinae and separated from the Hoplitinae where it was placed in the older in the 1957 edition of the Treatise on Invertebrate Paleontology, Part L (Ammonoidea). Genera of the Hoplitinae tend to be more robust, with broader whorls and stronger ribs.

Anahoplites is found in Cretaceous (Middle to the Late Albian) deposits from England, through Europe, all the way to the Transcaspian Oblast region in Russia to the east of the Caspian Sea. The Aube department, named after the local river, is the type locality of the Albian stage (d'ORBIGNY, 1842). 

A. planus from the French Coast

Two formations are recognized in the clay facies (the "Gault" auct.) of the stratotype, the Argiles tégulines de Courcelles (82 m), overlain by the Marnes de Brienne (43 m). The boundary between the two formations is well-defined at the top of an indurated bed and readily identifiable in the field.

This involute (113 mm) specimen shows evidence of cohabitation by some of his marine peers. We see two different bryozoa, an oyster and some serpulids making a living and leaving trace fossils on her flat sides. The top specimen was prepared with potase by José Juárez Ruiz of Spain. 

The lovely Anahoplites planus you see here to the lower right was found by Bertus op den Dries on the French coast in Albian deposits near Wissant, P5 and measures in at 8 cm. This on edge view gives you a very good sense of the keel.

FREE RESOURCES FOR TEACHERS AND STUDENTS

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. 

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 and good luck!

GRAPTOLITES

Graptolites (Graptolita) are colonial animals. The biological affinities of the graptolites have always been debatable. Originally regarded as being related to the hydrozoans, graptolites are now considered to be related to the pterobranchs, a rare group of modern marine animals.

The graptolites are now classed as hemichordates (phylum Hemichordata), a primitive group that probably shares a common ancestry with the vertebrates.

In life, many graptolites appear to have been planktonic, drifting freely on the surface of ancient seas or attached to floating seaweed by means of a slender thread. Some forms of graptolite lived attached to the seafloor by a root-like base. Graptolite fossils are often found in shales and slates. The deceased planktonic graptolites would sink down to and settle on the seafloor, eventually becoming entombed in the sediment and are thus well preserved.

Graptolite fossils are found flattened along the bedding plane of the rocks in which they occur. They vary in shape, but are most commonly dendritic or branching (such as Dictoyonema), saw-blade like, or "tuning fork" shaped, such as Didymograptus murchisoni.

ICHTHYOSAUR VERTEBRAE

A wee ichthyosaur vertebrae from Berlin-Ichthyosaur State Park, Nevada, USA. This area in central Nevada is a very important locality for our understanding of the Carnian-Norian boundary (CNB) in North America. 

To picture our world at this time, most continents were merged into the supercontinent Pangaea, and there was a single global ocean, Panthalassa. Swimming in that ocean were the large marine reptiles we find in these Nevada exposures — and indeed worldwide — today.

On the land, we meet the earliest dinosaurs, Herrerasaurus and Eoraptor — around 230 Ma. 

The oldest well documented dinosaurian assemblage, in the Ischigualasto Formation, a Late Triassic fossiliferous formation and Lagerstätte in the Ischigualasto-Villa Unión Basin of the southwestern La Rioja Province and northeastern San Juan Province in northwestern Argentina, dates to this time as well.

If you are considering a visit to Berlin-Ichthyosaur State Park or indeed, Nevada, choose October. Not too hot, nor too cold — but it is tarantula breeding season — so step lively! 

Know Before You Go — Berlin-Ichthyosaur State Park

This is a wonderful place to explore for a very reasonable sum of $5.00 US. Open year-round (though check regarding accessibility during Covid).  

Contact information: Tel: 775-964-2440 / Email: bisp@parks.nv.gov. Pop these coordinates into your GPS to make your travel easier: HC-61 Box 61200, Austin, NV 89310

SAURAVUS: SAURAVUS COSTEI

The type species of Sauravus, Sauravus costei, is known from Blanzy, a town in the Saône-et-Loire department of France. 

This town and its adjacent community Montceau-les-Mines possess containing abundant Carboniferous fossils. These fossils are believed to have been from the Stephanian B stage of the Late Carboniferous, approximately 305 to 304 million years ago.

Sauravus cambrayi is known from Les Télots, a mine near Autun, Saône-et-Loire, France. 

Télots is the type locality of the Autunian stage, a period of time which is believed to correspond to part of the early Permian period. The geological formation to which Télots fossils belong is known as the Millery Formation. 

The specific part of the Permian to which this formation belongs to was unclear for many years. In 2014, Schneider et al. suggested that the Millery Formation dated to the middle Artinskian age, about 290 to 286 million years ago.

Sauravus spinosus is a rename of Scincosaurus spinosus, a Montceau-les-Mines scincosaurid described by C. Civet in 1982. Although that author considered the species to belong to Scincosaurus, in 1994 Jean-Michel Dutuit and D. Heyler believed considered it a species of Sauravus.

CHARIOCRINUS: FRANCE

Chariocrinus andrae, Collection: David Appleton

Crinoids are one of my favourite echinoderms. It is magical when all the elements come together to preserve a particularly lovely specimen in such glorious detail. 

This impressive block, chock full of lovely, well-preserved specimens of the crinoid, Chariocrinus andrae, hails from Bathonian outcrops in Beaune, Saône-et-Loire in the Bourgogne-Franche-Comté region of central-eastern France. They are intertwined to cover most of the surface area of the citrus coloured matrix. 

Crinoids are unusually beautiful and graceful members of the phylum Echinodermata. They resemble an underwater flower swaying in an ocean current. But make no mistake they are marine animals. Picture a flower with a mouth on the top surface that is surrounded by feeding arms. Awkwardly, add an anus right beside that mouth. That's him!

Crinoids with root-like anchors are called Sea Lilies. They have graceful stalks that grip the ocean floor. Those in deeper water have longish stalks up to 3.3 ft or a meter in length.

Then there are other varieties that are free-swimming with only vestigial stalks. They make up the majority of this group and are commonly known as feather stars or comatulids. 

Unlike the sea lilies, the feather stars can move about on tiny hook-like structures called cirri. It is these same cirri that allow crinoids to latch to surfaces on the seafloor. Like other echinoderms, crinoids have pentaradial symmetry. The aboral surface of the body is studded with plates of calcium carbonate, forming an endoskeleton similar to that in starfish and sea urchins.

These make the calyx somewhat cup-shaped, and there are few, if any, ossicles in the oral (upper) surface, an area we call the tegmen. It is divided into five ambulacral areas, including a deep groove from which the tube feet project, and five interambulacral areas between them. 

Crinoids are alive and well today. They are also some of the oldest fossils on the planet. We have lovely fossil specimens dating back to the Ordovician — if one ignores the enigmatic Echmatocrinus of the Burgess Shale. And they can be quite plentiful. Crinoid fossils, and in particular disarticulated crinoid columnals, can be so abundant that they at times serve as the primary supporting clasts in sedimentary rocks

This beautiful 7" x 6" piece was photographed in natural sunlight to help show off the amazing detail. Photo and collection of the deeply awesome David Appleton.

DELGADOCRINUS OPORTOVINUM

This exceptionally well-preserved crinoid, Delgadocrinus oportovinum, was found on October 11, 1905, by Nery Delgado during his work mapping the geology and paleontology of Portugal.

His find resulted in the creation of a new family, Delgadocrinoinidae, a new genus and a new species.

Ausich et al. published on New and Revised Occurrences of Ordovician Crinoids from Southwestern Europe in the Journal of Paleontology, November 2007. In their work, they honour Delgado. His find was the first record of an Ordovician crinoid from Portugal, Delgadocrinus oportovinum, marking it as the oldest known crinoid from the Iberian Peninsula, Arenigian/Oretanian boundary, early Darriwilian.

The team took a comprehensive look at the Ordovician crinoids of southwestern Europe, including taxa based on articulated crowns and stems. This summary incorporates new material, new localities, and a revision of some southwestern Europe occurrences and is well worth a read. The Type Specimen you see here is now housed in the Natural History Museum of Lisbon. Luis Lima shared a photo of his recent visit to their beautiful collections and kindly granted permission to share the photo.

Reference: Ausich, William & Sá, Artur & Gutiérrez-Marco, Juan. (2007). New and revised occurrences of Ordovician crinoids from southwestern Europe. Journal of Paleontology - J PALEONTOL. 81. 1374-1383. 10.1666/05-038.1.

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.