
Monday, 21 November 2022
SEA ANEMONE NURSERY
Most actinarians are sessile; that is, they live attached to rocks or other substrates and do not move, or move only very slowly by contractions of the pedal disk. A number of anemones burrow into sand, and a few can even swim short distances, by bending the column back and forth or by "flapping" their tentacles. In all, there are about 1000 species of sea anemone in the world's oceans.
Sea anemones breed by liberating sperm and eggs through their mouth into the sea. The fertilized eggs develop into planula larvae which, after being planktonic for a while, settle on the seabed and develop directly into juvenile polyps. Sea anemones can also breed asexually, by breaking in half or into smaller pieces which regenerate into polyps.
They are sometimes kept in reef aquariums; the global trade in marine ornamentals is expanding and threatens sea anemone populations in some localities, as the trade depends on collection from the wild. Most Actiniaria do not form hard parts that can be recognized as fossils, but a few fossils of sea anemones do exist; Mackenzia, from the Stephen Formation, Middle Cambrian Burgess Shale of Canada, is the oldest fossil identified as a sea anemone.
Some fossil sea anemones have also been found from the Lower Cambrian of China. The new find lends support to genetic data that suggests anthozoans — anemones, corals, octocorals and their kin — were one the first Cnidarian groups to diversify.
Reference: Conway Morris, S. (1993). "Ediacaran-like fossils in Cambrian Burgess Shale–type faunas of North America". Palaeontology. 36 (31–0239): 593–635.
Sunday, 20 November 2022
HERMIT CRAB: XALA'IS GUGWIS
This little cutie is a hermit crab and he is wearing a temporary home borrowed from one of our mollusc friends.
His body is a soft, squishy spiral that he eases into the perfect size shell time and time again as he grows. His first choice is always the empty shell of a marine snail but will get inventive in a pinch — nuts, wood, serpulid worm tubes, aluminium cans or wee plastic caps.
They are inventive, polite and patient. I think of them as I hunt for elusive parking in Kitsilano and watch friends lining up for scarce apartment rentals.
You see, a hermit crabs' desire for the perfect bit of real estate will have them queueing beside larger shells — shells too large for them — to wait upon a big hermit crab to come along, discard the perfect home and slip into their new curved abode. This is all done in an orderly fashion with the hermit crabs all lined up, biggest to smallest to see who best fits the newly available shell.
There are over 800 species of hermit crab — decapod crustaceans of the superfamily Paguroidea. Their lineage dates back to the Jurassic, 200 million years ago. Their soft squishy, weakly calcified bodies do not fossilize all that often but when they do the specimens are spectacular.Think of all the species of molluscs these lovelies have had a chance to try on — including ammonites — and all the shells that were never buried in sediment to become fossils because they were harvested as homes.
On the shores of British Columbia, the hermit crab I come across the most is the Grainyhand hermit crab, Pagurus granosimanus. These wee fellows have tell-tale orange-brown antennae and olive green legs speckled with blue or white dots.
In the Kwak̓wala language of the Kwakiutl or Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest and my family, a shell is known as x̱ala̱'is and gugwis means house on the beach. I do not know the Kwak’wala word for hermit crab, so I will think of these cuties as x̱ala̱'is gugwis — envisioning them finding the perfect sized shell on the surf worn shores of Tsax̱is, Fort Rupert, Vancouver Island.
Saturday, 19 November 2022
EUSTHENOPTERON FORDI: DEVONIAN FISH
If you look closely at this specimen, you can see the remarkable 3-D and soft-bodied preservation. This fish specimen reminds me of the ray-finned fossil fish you see in carbonate concretion from Lower Cretaceous deposits in the Santana Formation, Brazil.
Eusthenopteron would have shared our ancient seas with the first ammonites and primitive sharks, along with well-established fauna including the trilobites, brachiopods, coral reefs and a whole host of interesting arthropods.
Miguasha National Park / Parc National de Miguasha, is a protected area near Carleton-sur-Mer on the Gaspé Peninsula along the south side of the Saint Lawrence River to the east of the Matapedia Valley in Quebec, Canada. It was created in 1985 by the Government of Quebec and designated as a World Heritage Site in 1999 in honour of paleontological significance for Devonian fish, flower and spore fossils.
These fossils represent five of the six main fossil fish groups recorded from the Devonian (370 million years ago) including specimens of the lobe-finned fish and tetrapods. We see the placoderms, armoured prehistoric fish, in their heyday, dominating almost every known aquatic environment. The Devonian is known as the 'Age of Fishes,' but it could have equally been called the 'Age of Spores,' as this was a time of significant adaptive radiation of terrestrial biota and free-sporing vascular plants. Immense forests carpeted the continents and we see the first of the plant groups evolving leaves, true roots and seeds.
The site was discovered in 1842 by a local geologist and medical doctor, Abraham Gesner. He shared much of his collection with both the British Museum and Royal Scottish Museum for further study. Other names for this site are the Miguasha Fossil Site, the Bay of Escuminac Fossil Site, the Upper Devonian Escuminac Formation, and the Hugh-Miller Cliffs. It is also sometimes referred to on fossil specimens as 'Scaumenac Bay' or 'Scaumenac Bay P.Q. Photo credit to the deeply awesome John Fam
Friday, 18 November 2022
THE EVOLUTION OF FISH
When we envision fish, we generally picture large eyes, gills, a well-developed mouth. The earliest animals that we classify as fish appeared as soft-bodied chordates who lacked a true spine. While they were spineless, they did have notochords, a cartilaginous skeletal rod that gave them more dexterity than the cold-blooded invertebrates who shared those ancient seas and evolved without a backbone. Fish would continue to evolve throughout the Paleozoic, diversifying into a wide range of forms. Several forms of Paleozoic fish developed external armour that protected them from predators. The first fish with jaws appeared in the Silurian period, after which many species, including sharks, became formidable marine predators rather than just the prey of arthropods.
Fishes in general respire using gills, are most often covered with bony scales and propel themselves using fins. There are two main types of fins, median fins and paired fins. The median fins include the caudal fin or tail fin, the dorsal fin, and the anal fin. Now there may be more than one dorsal, and one anal fin in some fishes.
The paired fins include the pectoral fins and the pelvic fins. And these paired fins are connected to, and supported by, pectoral and pelvic girdles, at the shoulder and hip; in the same way, our arms and legs are connected to and supported by, pectoral and pelvic girdles. This arrangement is something we inherited from the ancestors we share with fishes. They are homologous structures.
When we speak of early vertebrates, we're often talking about fishes. Fish is a term we use a lot in our everyday lives but taxonomically it is not all that useful. When we say, 'fish' we generally mean an ectothermic, aquatic vertebrate with gills and fins.
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Eohiodon Fish Fossil / McAbee |
There are fragments of bone-like tissues from as early as the Late Cambrian with the oldest fossils that are truly recognizable as fishes come from the Middle Ordovician from North America, South America and Australia. At the time, South America and Australia were part of a supercontinent called Gondwana. North America was part of another supercontinent called Laurentia and the two were separated by deep oceans.
Thursday, 17 November 2022
FOSSIL AMPHIBIANS OF NOVA SCOTIA
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Dendrerpeton acadianum, an extinct amphibian |
These little cuties belong to an extinct genus of amphibians who loved wet, swampy wetlands similar to those we find in the bayous of Mississippi today.
Dendrerpeton is the primitive sister-group to a clade of Temnospondyls that includes Trimerorhachoids, the Eryopoids — Ervops, Parioxys, & Sclerocephalus — Zatracheids & Dissorophoids.
This little guy along with finding the first true reptile, Hylonomus lyelli, ancestor of all dinosaurs that would rule the Earth 100 million years later serve as the reference point where animals finally broke free of the water to live on land. This evolutionary milestone recorded at Joggins remains pivotal to understanding the origins of all vertebrate life on land, including our own species.
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Joggins records life in a once a wet, swampy wetland |
Wednesday, 16 November 2022
FOSSILS FROM TURTLE ISLAND'S EASTERN COASTLINE
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Pennsylvanian Coal Age Ecosystem, 300-Million-Years-Old |
References & further reading:
Joggins Fossil Cliffs: https://jogginsfossilcliffs.net/cliffs/history/
Image: Hylonomus lyelli, Una ricostruzione di ilonomo by Matteo De Stefano/MUSEThis file was uploaded by MUSE - Science Museum of Trento in cooperation with Wikimedia Italia., CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=48143186
Image: Arthropleura: Par Tim Bertelink — Travail personnel, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=48915156
Joggins Map: Joggins Fossil Cliffs: https://jogginsfossilcliffs.net/cliffs/history/
Tuesday, 15 November 2022
GULLS ON THE FORESHORE: T'SIK'WI
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A gull cries in protest at not getting his share of a meal |
Monday, 14 November 2022
FIRST DINOSAUR FROM VANCOUVER ISLAND
Hadrosaurs lived as part of a herd, dining on pine needles, horsetails, twigs and flowering plants.
Hadrosaurs are ornithischians — an extinct clade of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. They are close relatives and possibly descendants of the earlier iguanodontid dinosaurs.
At their emergence in the fossil record, they were quite small, roughly three meters long. That's slightly smaller than an American bison. They evolved during the Cretaceous with some of their lineage reaching up to 20 meters or 65 feet.
Hadrosaurs are very rare in British Columbia but a common fossil in our provincial neighbour, Alberta, to the east. Here, along with the rest of the world, they were more abundant than sauropods and a relatively common fossil find. They were common in the Upper Cretaceous of Europe, Asia, and North America.
There are two main groups of Hadrosaurs, crested and non-crested. The bony crest on the top of the head of the hadrosaurs was hollow and attached to the nasal passages. It is thought that the hollow crest was used to make different sounds. These sounds may have signalled distress or been the hadrosaur equivalent of a wolf whistle used to attract mates. Given their size it would have made for quite the trumpeting sound.
This beautiful specimen graces the back galleries of the Courtenay and District Museum on Vancouver Island, British Columbia, Canada. I was very fortunate to have a tour this past summer with the deeply awesome Mike Trask joined by the lovely Lori Vesper. The museum houses an extensive collection of palaeontological and archaeological material found on Vancouver Island, many of which have been donated by the Vancouver Island Palaeontological Society.
Dan Bowen, Chair of the Vancouver Island Palaeontological Society, shared the photo you see here of the first partly articulated dinosaur from Vancouver Island ever found. The vertebrate photo and illustration are from a presentation by Dr. David Evans at the 2018 Paleontological Symposium in Courtenay. The research efforts of the VIPS run deep in British Columbia and this new very significant find is no exception. A Hadrosauroid dinosaur is a rare occurrence and further evidence of the terrestrial influence in the Upper Cretaceous, Nanaimo Group, Vancouver Island — outcrops that we traditionally thought of as marine from years of collecting well-preserved marine fossil fauna.
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CDM 002 / Hadrosauroid Caudal Vertebrae |
Mike was leading a fossil expedition on the Trent River. While searching through the Upper Cretaceous shales, the group found an articulated mass of bones that looked quite promising.
Given the history of the finds in the area, the bones were thought to be from a marine reptile.
Since that time, we've found a wonderful terrestrial helochelydrid turtle, Naomichelys speciosa, but up to this point, the Trent had been known for its fossil marine fauna, not terrestrial. Efforts were made to excavate more of the specimen, and in all more than 25 associated vertebrae were collected with the help of some 40+ volunteers. Identifying fossil bone is a tricky business. Encased in rock, the caudal vertebrae were thought to be marine reptile in origin. Some of these were put on display in the Courtenay Museum and mislabeled for years as an unidentified plesiosaur.
In 2016, after years of collecting dust and praise in equal measure, the bones were reexamined. They didn't quite match what we'd expect from a marine reptile. Shino Sugimoto, Fossil Preparator, Vertebrate Palaeontology Technician at the Royal Ontario Museum was called in to work her magic — painstakingly prepping out each caudal vertebrae from the block.
Drawing of Trent River Hadrosauroid Caudal Vertebrae |
There are well-defined long, raked neural spines that expand distally — up and away from the acoelous centrum.
This fellow has kissing cousins over in the state of New Jersey where this species is the official state fossil. The first of his kind was found by John Estaugh Hopkins in New Jersey back in 1838. Since that time, we've found many hadrosaurs in Alberta, particularly the Edmontosuaurs, another member of the subfamily Hadrosaurine.
In 1978, Princeton University found fifteen juvenile hadrosaurs, Maiasaura ("good mother lizard") on a paleontological expedition to the Upper Cretaceous, Two Medicine Formation of Teton County in western Montana.
Photo One: Fossil Huntress / Heidi Henderson, VIPS
Sunday, 13 November 2022
Saturday, 12 November 2022
FOSSILS OF THE LONDON CLAY
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Birds, Snakes & Mammals, London Clay |
The London Clay Formation is a marine geological formation of Ypresian (early Eocene Epoch, c. 56–49 Ma) age which outcrops in the southeast of England.
The exposures are well-known for their variety of fossil fauna. The fossils from the lower Eocene sections tell us about a moderately warm, tropical to subtropical climate.
It was with the greatest pleasure that I came across some of the wonderful fossil specimens found by Martin Rayner and his father over the better part of 40-years worth of dedicated collecting. These excellent examples of the London Clay fauna hail from Sheppey, Seasalter and Tankerton.
You may recall that Martin is a co-author of London Clay Fossils of Kent and Essex. The book is a collectors' guide to the fossil animals and plants of the London Clay from river and coastal exposures in Kent and Essex. It is known locally as the Fossil Bible.
This superb book is published by the Medway Fossil and Mineral Society and was written by four of the Society members, David Rayner, Tony Mitchell, Martin Rayner and Fred Clouter.It the essential field guide for use by both beginners and the more experienced — and likely the definitive work on the subject for many years to come.
The book includes when to collect, equipment, cleaning, preparation and preservation of specimens, sieving, storage and cataloguing, geology and a list of fourteen collecting sites — six with site location maps, access details and collecting techniques.
There is a hugely useful identification section and comprehensive terminology for the invertebrates, vertebrates and plants of the London Clay. Here you'll find all of the yummy foraminifera, bryozoa, worms, trace fossils, corals, barnacles, lobsters, stomatopods, crabs, insects, brachiopods, bivalves, scaphopods, gastropods, nautili, coleoids, crinoids, echinoids and starfish. Also included are the sharks, rays, chimaera, bony fish, otoliths, turtles, snakes, crocodiles, birds, mammals and plant material.
If you fancy picking up a copy, here is the UKGE link: https://www.ukge.com/en-ie/London-Clay-Fossils-of-Kent-and-Essex__p-3291.aspx
Photo One: Martin Rayner: Snake, Bird and Mammal finds from the London Clay, mostly from Sheppey and Seasalter, UK
Photo Two: Martin Rayner: A rare skull from the remains of the sea snake Palaeophis toliapicus.
Friday, 11 November 2022
TARANTULAS AND AMMONOIDS OF NEVADA
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.
Thursday, 10 November 2022
AMMONOIDS, LIMESTONE AND SALT: HALLSTATT
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Hallstatt Salt Mines, Austria / Permian Salt Diapir |
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.
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.
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Hallstatt and the Hallstatt Sea, Austria |
The Hallstatt mine exploits a Permian salt diapir that makes up some of this area’s oldest rock.
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.
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.
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Hallstatt Beinhaus Ossuary, Hallstatt, Austria |
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.
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.
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Hallstatt, Salzkammergut region, Austria |
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.
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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
Wednesday, 9 November 2022
TRACKING THROUGH THE TRIASSIC
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Grambergia sp. Middle Triassic Ammonoid of BC, Canada |
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.
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.
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Triassic ammonoids, West Humboldt Mountains, Nevada, USA |
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.
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Middle Triassic (Anisian/Ladinian) Fauna |
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.
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.
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Juvavites sp. Geological Survey of Canada. Photo: John Fam |
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.
At the end of the Rhaetian (part of the Triassic period), most of the ammonites had died out. These are the lovely coiled molluscs you often see in museums and gift shops that sell fossils. They are a particular favourite of mine and they are both beautiful and useful to tell us much about deep time. 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 |
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
Tuesday, 8 November 2022
FROM RUSSIA WITH LOVE: CADOCHAMOUSSETIA
This beautiful — fully Бомба — specimen is courtesy of Emil Black and one of the finest in his collection.
In the last decade, the Siberian zonal scale of the Callovian has been considerably revised because of new ammonite collections from the Callovian reference sections in Siberia. Species of Cadoceratinae thought of as exclusively European were recorded for the first time in Siberia.
The genus Cadochamoussetia (Mitta, 1996) was established in European Russian (Gerasimov et al., 1996) and later in England (Navarro et al., 2005).
In the lower Callovian of European Russia, beds with Cadochamoussetia were originally considered part of the Cadochamoussetia subpatruus upper subzone of the Cadoceras elatmae Zone (Mitta, 2000).
Photos: Cadochamoussetia tschernyschewi (12 cm) graciously shared by the deeply awesome of Emil Black. He has shared many wonderful specimen photos and stories with me over the years and I am honoured by his generosity in doing so. It is because of him that I am able to share these with all of you! So a collective, Спасибо, мой друг. Spasibo, moy drug.
- The Early Callovian genus Сadochamoussetia (Ammonoidea, Cardioceratidae) in the lower reaches of the Anabar River, Northern Central Siberia; Original Russian Text © V.G. Kniazev, S.V. Meledina, A.S. Alifirov, B.L. Nikitenko, 2017, published in Stratigrafiya, Geologicheskaya Korrelyatsiya, 2017, Vol. 25, No. 4, pp. 26–41.
- Kniazev, V.G., Meledina, S.V., Alifirirov, A.S., and Kutygin, R.V., The Middle Callovian stage of evlution of Siberian cardioceratids, in Sovremennye problemy izucheniya golovonogikh mollyuskov. Morfologiya, sistematika, evolyutsiya, ekologiya i biostratigrafiya. Vyp. 4 (Current Problems in Study of Cephalopods: Morphology, Systematics, Evolution, Ecology, and Biostratigraphy. Iss. 4), Moscow: Paleontol. Inst. Ross. Akad. Nauk, 2015, pp. 40–45.
- Meledina, S.V, Correlation of the Bajocian and Bathonian zones in light of new paleontological data, Stratigr. Geol. Correl., 2014, vol. 22, no. 6, pp. 594–605.
- Kniazev, V.G., Meledina, S.V., Alifirirov, A.S., and Kutygin, R.V., The Middle Callovian stage of evlution of Siberian cardioceratids, in Sovremennye problemy izucheniya golovonogikh mollyuskov. Morfologiya, sistematika, evolyutsiya, ekologiya i biostratigrafiya. Vyp.
- If you do not speak Russian that roughly translates to: Current Problems in Study of Cephalopods: Morphology, Systematics, Evolution, Ecology, and Biostratigraphy. Iss. 4, Moscow: Paleontol. Inst. Ross. Akad. Nauk, 2015, pp. 40–45.
- Meledina, S.V, Correlation of the Bajocian and Bathonian zones in light of new paleontological data, Stratigr. Geol. Correl., 2014, vol. 22, no. 6, pp. 594–605.
- Treatise on Invertebrate Paleontology. Pt. L. Mollusca 4, Cephalopoda, Ammonoidea, N.Y. Lawrence: Geol. Soc. Amer., Univ. Kansas Press, 1957, vol. 4. TSCreatorProvisualization of Enhanced Geologic Time Scale 2004 database (Vers. 6.2, 2014). http://www.tscreator. org, 2014.
- Treatise on Invertebrate Paleontology. Pt. L. Mollusca 4, Cephalopoda, Ammonoidea, N.Y. Lawrence: Geol. Soc. Amer., Univ. Kansas Press, 1957, vol. 4. TSCreatorProvisualization of Enhanced Geologic Time Scale 2004 database (Vers. 6.2, 2014). http://www.tscreator. org, 2014.
Monday, 7 November 2022
OH, SHINY. FOSSILS PRESERVED IN PYRITE
Sometimes folk add a coating of brass to increase the aesthetic appeal — a practice is frowned upon in paleontological communities.
Pyrite, sometimes called Fool's Gold, is a brass-yellow mineral with a bright metallic lustre. I popped a photo of some pyrite below so you can see the characteristic shape of its cubic crystal system.
Fool's Gold has a chemical composition of iron sulfide (FeS2) and is the most common sulfide mineral. It forms at high and low temperatures usually in small quantities, in igneous, metamorphic, and sedimentary rocks. If these sulfide minerals are close at hand when a fossil is forming, they can infuse specimens, replacing their mineral content to beautiful effect.
When we find a fossil preserved with pyrite, it tells us a lot about the conditions on the seabed where the organism died. Pyrite forms when there is a lot of organic carbon and not much oxygen in the vicinity.
The reason for this is that bacteria in sediment usually respire aerobically (using oxygen), however, when there is no oxygen, they respire without oxygen (anaerobic) typically using sulphate.
Sulphate is a polyatomic anion with the empirical formula SO2−4. It is generally highly soluble in water. Sulfate-reducing bacteria, some anaerobic microorganisms, such as those living in sediment or near deep-sea thermal vents, use the reduction of sulfates coupled with the oxidation of organic compounds or hydrogen as an energy source for chemosynthesis.
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The sulfide mineral Pyrite, FeS2 |
So, when we find a fossil preserved in pyrite, we know that it died and was buried in sediment with low quantities of oxygen and high quantities of organic carbon.
If you have pyrite specimens and want to stop them from decaying, you can give them a 'quick' soak in water (hour max) then wash them off, dry thoroughly in a warm oven.
Cool, then soak in pure acetone for a couple of days. Then soak in paraloid, a thermoplastic resin surface coating or acetone for a couple of days. Keep in a sealed container with a desiccant pack afterwards to keep them dry — or leave them out on display to enjoy knowing that the decay will come in time. We do this with cut flowers so why not fossils sometimes.
I have a friend who gives her pyrite fossils on display a quick thumb wipe with vasoline or petroleum jelly. I'm not sure if the hydrocarbons there will play nice over time but it will act as a protective barrier.