ANDROGYNOCERAS LATAECOSTA

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

This specimen was found, prepped and photographed by the lovely and talented Lizzie Hingley of Stonebarrow Fossils. 

And what a delightful surprise! It is quite a small nodule to contain a macroconch of this species. Generally, these smaller concretions contain the diminutive male microconchs of Androgynoceras (Hyatt, 1867) if you are lucky — sometimes a Tragophylloceras loscombi (Sowerby, 1814) — or nothing at all if you are not. 

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

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

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

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

Unfortunately, the green ammonite beds at Charmouth preserve only juvenile macroconchs so we don’t get to appreciate the similarity of the mature adult shell form. We see them at a size where individuals can look very different from each other. 

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

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

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

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

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

ORYGMASPIS SPINULA OF THE MCKAY GROUP

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

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

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

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

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

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

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

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

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

References:

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

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

TRIASSIC BEAUTY: ALBERTONIA

Triassic Fossil Fish, Albertonia sp. 

This beauty with the graceful sail-like fins is the Early Triassic ganoid fish, Albertonia sp., an extinct bony fish from British Columbia, Canada. 

Specimens of this lovely have been found in the Vega-Phroso Siltstone Member of the Sulphur Mountain Formation near Wapiti Lake in British Columbia and the Lower Triassic Montney Formation of Alberta. 

Early Triassic fish have been described from several outcrops in the Western Canada Sedimentary Basin of the Rocky Mountains. The best known and most prolific of these are from sites near Wapiti Lake in northeastern British Columbia. Here specimens of bony fish with their heavy ganoid and cosmoid scales are beautifully preserved. Four genera of Early Triassic fishes — the ray-finned actinopterygians Albertonia, Bobasatrania, Boreosomus, and the lobe-finned coelacanth (sarcopterygian), Whiteia — are found in abundance in the Wapiti Lake exposures.

This particular species is one of my favourites. Albertonia is a member of the ganoid fish family Parasemionotidae, which is amongst the most advanced and abundant of Triassic subholostean families of fish. The preservation here really shows the beauty of form of this species who likely died and was preserved in sediment at the bottom of an ocean with an anoxic environment. 

These fellows lived in deep marine waters, dining on plankton & other small organisms. Most specimens are 35-40cm in length. They have a large, sail-shaped dorsal fin and rather smallish ventral fins. Their pectoral fins were incredibly long compared to the rest of the body, and they too resembled sails. The preservation here is quite remarkable with each square-shaped scale preserved in minute detail.

ANCIENT ARTHROPOD FROM PAIWU

This large, showy bivalved arthropod is a Tuzoia sinesis (Pan, 1957) from Cambrian deposits of the Balang Formation. The Balang outcrops in beautiful Paiwu, northwestern Hunan Province in southern China. 

The site is intermediate in age between the Lower Cambrian Chengjiang fauna of Yunnan and the Lower to Middle Cambrian, Kaili Lagerstätten of Guizhou in southwestern China.

This specimen was collected in October 2019 and is one of the many new and exciting arthropods to come from the site. Balang has a low diversity of trilobites and many soft-bodied fossils similar in preservation to Canada's Burgess Shale. 

Some of the most interesting finds include the first discovery of anomalocaridid appendages — Appendage-F-Type. These were found along with the early arthropod Leanchoiliids — with his atypical frontal appendages and questionable phylogenetic placement — and the soft-shelled trilobite-like arthropod, Naraoiidae.

While the site is not as well-studied as the Chengjiang and Kaili Lagerstätten, it looks very promising. The exceptionally well-preserved fauna includes algae, sponges, chancelloriids, cnidarians, worms, molluscs, brachiopods, trilobites and a few non-mineralized arthropods. It is an exciting time for Cambrian palaeontology. The Balang provides an intriguing new window into our ancient seas and the profound diversification of life that flourished there.

THE DUDLEY BUG

Calymene blumenbachii, Theresa Paul Spink Dunn

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

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

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

THALASSINA ANOMALA: MUD LOBSTER

This fellow is the scorpion mud lobster, Thalassina anomala (Herbst, 1804), a species of decapod crustacean in the family Thalassinidae. He's a little sweetie with very interesting anatomy. 

Lobsters have their brains in their throats and they breathe and listen with their legs. To top all that wackiness off, they taste with their feet.

These fellows are not as desired as their larger cousins as food for us hoomins. True to their name, they taste a bit muddy. 

Thalassina anomala is an important member of the mangrove ecosystems in which they live. They are night borrowers who excavate om their search for tasty organic material to snack on. They push organic-rich soil from deep in the ground back up to the surface — creating huge mounds. Their burrowing also helps to aerate tidal waters. 

The mud mounds they build are pretty massive in scale in comparison to these fellows. The specimen you see here is 6.5 cm long but others can grow up to 30 cm and build mounds up to 3 metres in height. These mounds provide important habitat for other animals including Odontomachus malignus (an ant), termites, Episesarma singaporense (tree-climbing crab), Wolffogebia phuketensis (mangrove mud shrimp), Acrochordus granulatus (file snake), and plants such as the tree Excoecaria agallochoa and ferns.

Lobsters are members of the phylum Arthropoda, Euarthropoda. They are crustaceans, like crabs, crayfish, krill, shrimp and prawns. Crustaceans belong to the arthropods, a group of animals with an armoured external skeleton (an exoskeleton), a segmented body and jointed legs. The hard exoskeleton is the part that’s preserved as a fossil. This fellow has the typical tall, ovoid carapace and presumably, a short rostrum — though his rostrum is partially hidden in the matrix. 

The specimen you see here hails from Pleistocene deposits near Gunn Point, an outer rural locality sandwiched between the Howard and Adelaide Rivers east of Darwin in the Northern Territory of Australia. His cousins can be found burrowing in the muds of brackish mangrove swamps and estuaries of the Indian Ocean and the western Pacific Ocean today. 

HOMARUS KARELSNSIS: LOBSTER FROM LEBANON

An artfully enhanced example of Homarus hakelensis, an extinct genus of fossil lobster belonging to the family Nephrophidae. Homarus is a genus of lobsters, which include the common and commercially significant species Homarus americanus (the American lobster) and Homarus gammarus (the European lobster).

The Cape lobster, which was formerly in this genus as H. capensis, was moved in 1995 to the new genus Homarinus.

Lobsters have long bodies with muscular tails and live in crevices or burrows on the seafloor. Three of their five pairs of legs have claws, including the first pair, which are usually much larger than the others.

Highly prized as seafood, lobsters are economically important and are often one of the most profitable commodities in coastal areas they populate. Commercially important species include two species of Homarus — which looks more like the stereotypical lobster — from the northern Atlantic Ocean, and scampi — which looks more like a shrimp — the Northern Hemisphere genus Nephrops and the Southern Hemisphere genus Metanephrops. Although several other groups of crustaceans have the word "lobster" in their names, the unqualified term lobster generally refers to the clawed lobsters of the family Nephropidae.

Clawed lobsters are not closely related to spiny lobsters or slipper lobsters, which have no claws or chelae, or to squat lobsters. The closest living relatives of clawed lobsters are the reef lobsters and the three families of freshwater crayfish. This cutie was found in Cretaceous outcrops at Hâdjoula. The sub‐lithographical limestones of Hâqel and Hâdjoula, in north‐west Lebanon, produce beautifully preserved shrimp, fish, and octopus. The localities are about 15 km apart, 45 km away from Beirut and 15 km away from the coastal city of Jbail. 

PHYLLOCERAS VELLEDAE

Lovely defined sutures on this rather involute, high-whorled ammonite from the middle part of the Lower Albian in the Mahajanga Province, northwestern Madagascar. This specimen of Phylloceras velledae (Michelin) has a shell with a small umbilicus, arched, acute venter, and at some growth stage, falcoid ribs that spring in pairs from umbilical tubercles, disappearing on the outer whorls.

While the large island of Madagascar off the southeast coast of Africa is known more for exotic lemurs, rainforests & beaches, it also boasts some of the world's loveliest fossils.

This specimen is from a quarry near the top of an escarpment, 3 km to the west of the village of Ambatolafia (coordinates: Lat. 16.330 23.600 S, Long. 46.120 10.20 E). Judging from plate tectonic reconstruction (Stampfli & Borel, 2002), the area was located in middle latitudes within the tropical-subtropical climatic zone at palaeo-latitudes of 40E45.S in the late Early Cretaceous of the early Albian approximately 113.0 ± 1.0 Ma to 100.5 ± 0.9 Ma. 

Madagascar was carved off from the African-South American landmass early on. The prehistoric break-up of the supercontinent Gondwana separated the Madagascar–Antarctica–India landmass from the Africa–South America landmass around 135 million years ago. Madagascar later split from India about 88 million years ago, during the Late Cretaceous, so the native plants and animals on the island evolved in relative isolation. It is a green and lush island country with more than it's fair share of excellent fossil exposures. 

Along the length of the eastern coast runs a narrow and steep escarpment containing much of the island's remaining tropical lowland forest. If you could look beneath this lush canopy, you'd see rocks of Precambrian age stretching from the east coast all the way to the centre of the island. The western edge is made up of sedimentary rock from the Carboniferous to the Quaternary. The beauty you see here is from sedimentary exposures from northwestern Madagascar and is in my personal collection. There is an exceptionally well-preserved and unusually large specimen in the collections of João Da Costa that I'll photograph and include in a future post.

SULPHATES AND CLIMATE CHANGE

The main direct effect of sulfates on the climate involves the scattering of light, effectively increasing the Earth's albedo. The term albedo was introduced into optics by Johann Heinrich Lambert in his 1760 work Photometria.

Albedo is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that reflects all incident radiation. The average albedo of the Earth from the upper atmosphere, its planetary albedo, is 30–35% because of cloud cover, but widely varies locally across the surface because of different geological and environmental features.

This effect is moderately well understood and leads to cooling from the negative radiative forcing of about 0.4 W/m2 relative to pre-industrial values, partially offsetting the larger (about 2.4 W/m2) warming effect of greenhouse gases. The effect is strongly spatially non-uniform, being largest downstream of large industrial areas.

% of Diffusely Reflected Sunlight

The first indirect effect is also known as the Twomey effect. Sulfate aerosols can act as cloud condensation nuclei and this leads to greater numbers of smaller droplets of water. Many smaller droplets can diffuse light more efficiently than a few larger droplets. 

The second indirect effect is the further knock-on effects of having more cloud condensation nuclei. It is proposed that these include the suppression of drizzle, increased cloud height, to facilitate cloud formation at low humidities and longer cloud lifetime. Sulfate may also result in changes in the particle size distribution, which can affect the clouds radiative properties in ways that are not fully understood. 

Chemical effects such as the dissolution of soluble gases and slightly soluble substances, surface tension depression by organic substances and accommodation coefficient changes are also included in the second indirect effect.

The indirect effects probably have a cooling effect, perhaps up to 2 W/m2, although the uncertainty is very large. Sulfates are therefore implicated in global dimming. Sulfate is also the major contributor to a stratospheric aerosol formed by oxidation of sulfur dioxide injected into the stratosphere by impulsive volcanoes such as the 1991 eruption of Mount Pinatubo in the Philippines. This aerosol exerts a cooling effect on climate during its 1-2 year lifetime in the stratosphere

Diagram: The percentage of diffusely reflected sunlight relative to various surface conditions. By CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=1060378

References: 

• Lewis, Gilbert N. (1916). "The Atom and the Molecule". J. Am. Chem. Soc. 38: 762–785. doi:10.1021/ja02261a002. (See page 778.)
• Pauling, Linus (1948). "The modern theory of valency". J. Chem. Soc.: 1461–1467. doi:10.1039/JR9480001461.
• Coulson, C. A. (1969). "d Electrons and Molecular Bonding". Nature. 221: 1106. Bibcode:1969Natur.221.1106C. doi:10.1038/2211106a0.
• Mitchell, K. A. R. (1969). "Use of outer d orbitals in bonding". Chem. Rev. 69: 157. doi:10.1021/cr60258a001.

PYRITE PRESERVATION

Ammonite Preserved in Pyrite. Fossil Huntress

We sometimes find fossils preserved by pyrite. They are prized as much for their pleasing gold colouring as they are for their scientific value as windows into the past. Sometimes folk add a coating of brass to increase the aesthetic appeal. Though this practice is frowned upon in paleontological communities.

Pyrite is a brass-yellow mineral with a bright metallic lustre. It 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.

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.

High quantities of organic carbon in the sediment form a barrier to oxygen in the water. This also works to encourage anaerobic respiration. Anaerobic respiration using sulphate releases hydrogen sulphide, which is one of the major components in pyrite. 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.

AMMOLITE

Ammolite is an opal-like organic gemstone found primarily along the eastern slopes of the Rocky Mountains of North America. It is made of the fossilized shells of ammonites, which in turn are composed primarily of aragonite, the same mineral contained in nacre, with a microstructure inherited from the shell. It is one of few biogenic gemstones; others include amber and pearl.

The chemical composition of ammolite is variable, and aside from aragonite may include a mix of calcite, silica, pyrite or other minerals. The shell itself may contain a number of trace elements based on the chemical composition of the original sediments. They can include aluminium, barium, chromium, copper, iron, magnesium, manganese, strontium, titanium, and vanadium. 

Its crystallography is orthorhombic. Its hardness is 3.5–4.5, and its specific gravity is 2.60–2.85. The refractive index of Canadian material (as measured via sodium light, 589.3 nm) is as follows: α 1.522; β 1.672–1.673; γ 1.676–1.679; biaxial negative. Under ultraviolet light, ammolite may fluoresce a mustard yellow.

Ammolite comes from the fossil shells of the Upper Cretaceous disk-shaped ammonites Placenticeras meeki and Placenticeras intercalare, and to a lesser degree, the cylindrical baculite, Baculites compressus. The ammonites that form our Alberta ammolite inhabited a prehistoric, inland subtropical sea that bordered the Rocky Mountains — this area is known today as the Cretaceous or Western Interior Seaway. As the ammonites died, they sank to the bottom and were buried by layers of bentonitic mud that eventually became shale. Many gem-quality ammonites are found within siderite concretions. These sediments preserved the aragonite of the shells, preventing it from converting to calcite.

Ammolite from the Bearpaw Formation

An iridescent opal-like play of colour is shown in fine specimens, mostly in shades of green and red; all the spectral colours are possible, however. The iridescence is due to the microstructure of the aragonite: unlike most other gems, whose colours come from light absorption, the iridescent colour of ammolite comes from interference with the light that rebounds from stacked layers of thin platelets that make up the aragonite. 

The thicker the layers, the more reds and greens are produced; the thinner the layers, the more blues and violets predominate. Reds and greens are the most commonly seen colours, owing to the greater fragility of the finer layers responsible for the blues. When freshly quarried, these colours are not especially dramatic; the material requires polishing and possibly other treatments in order to reveal the colours' full potential.

Ammolite itself is very thin. It is generally 0.5–0.8 millimetres (0.02–0.03 inches) thick. This thin coating covers a matrix typically made up of grey to brown shale, chalky clay, or limestone. 

Frost shattering of these specimens is common. If left exposed to the elements the thin ammolite tends to crack and flake. Prolonged exposure to sunlight can also lead to bleaching of the generally intense colouration. The cracking results in a tessellated appearance, sometimes described as a "dragon skin" or referred to as a stained glass window pattern. 

Ammolite mined from deeper deposits may be entirely smooth or with a rippled surface. Occasionally a complete ammonite shell is recovered with its structure well-preserved: fine, convoluted lines delineate the shell chambers, and the overall shape is suggestive of a nautilus. While these shells may be as large as 90 centimetres (35.5 inches) in diameter, the iridescent ammonites (as opposed to the pyritized variety) are typically much smaller. Most fossilized shells have had their aragonite pseudomorphously replaced by calcite or pyrite, making the presence of ammolite particularly uncommon.

In 1981, ammolite was given official gemstone status by the World Jewellery Confederation (CIBJO), the same year commercial mining of ammolite began. It was designated the official gemstone of the City of Lethbridge, Alberta in 2007.

Ammolite is also known as aapoak — Kainah for "small, crawling stone" — gem ammonite, calcentine, and Korite. The latter is a trade name given to the gemstone by the Alberta-based mining company Korite. Roughly half of all ammolite deposits are contained within the Kainah (Kainaiwa) reserve, and its inhabitants play a major role in ammolite mining. Marcel Charbonneau and his business partner Mike Berisoff were the first to create commercial doublets of the gem in 1967. They went on to form Ammolite Minerals Ltd.

FOSSIL PRESERVATION: REPLACEMENT

Ancient life can be preserved as fossils in a number of ways. Replacement is one of the ways both shellfish and wood can be preserved as fossils. Replacement occurs as the original atomic composition of the living organism is replaced cell by cell by a new chemical structure. 

It is the chemical composition of the groundwater that determines what the composition of the fossil will be. A common type of replacement is silification. Silification is the process by which silica minerals such as quartz, chalcedony, and opal fill pores or replace existing minerals, rock, or wood.

Silicification occurs in the earth’s interior through the action of hydrothermal and cold water saturated with silica. As aluminosilicate rock is weathered, a great deal of silica is freed and dissolves. Much of the dissolved silica is carried to the sea, but in places, it moves downward and replaces various rock. 

Hydrothermally silicified carbonate rock is frequently associated with ores of mercury, antimony, and other nonferrous metals. At ordinary temperatures, loose rock on the bottom of lakes and seas is subject to silicification, as is solid rock; this occurs most frequently with limestones and dolomites, more rarely with clays and phosphorites. 

Accumulations of fine-grained quartz form when carbonate rocks are replaced and aggregates of quartz and chalcedony develop when clayey rock is replaced. The presence of fine-grained quartz and quartz and chalcedony aggregates in ultrabasic rock indicates that deposits of silicate ores of nickel and cobalt may be found. Excellent examples of silification are fossil molluscs and petrified forests.

AMMONITES: CHAMBERED BEAUTY

Ammonoids are 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 — octopus, squid, and cuttlefish — than they are to shelled nautiloids such as the living Nautilus species. The earliest ammonites appear during the Devonian, and the last species vanished in the Cretaceous–Paleogene extinction event. 

The chambered part of the ammonite shell is called a phragmocone. It contains a series of progressively larger chambers, called camerae — the singular is camera — that are divided by thin walls called septa —the singular is septum. You can see the interior of an ammonite with the discreet chambers in this lovely sliced Cleoniceras sp. from Madagascar.

Only the last and largest chamber, the body chamber, was occupied by the living animal at any given moment. As it grew, it added newer and larger chambers to the open end of the coil. Where the outer whorl of an ammonite shell largely covers the preceding whorls, the specimen is said to be involute. Anahoplites is a good example of this. Where it does not cover those preceding, the specimen is said to be evolute, something we see in the ammonite Dactylioceras.

A thin living tube called a siphuncle passed through the septa, extending from the ammonite's body into the empty shell chambers. Through a hyperosmotic active transport process, the ammonite emptied the water out of these shell chambers. This enabled it to control the buoyancy of the shell and thereby rise or descend in the water column.

A primary difference between ammonites and nautiloids is the siphuncle of ammonites — excepting Clymeniina — which runs along the ventral periphery of the septa and camerae — the inner surface of the outer axis of the shell — while the siphuncle of nautiloids runs more or less through the centre of the septa and camerae.

Clymenia has a closely coiled evolute shell that may be faintly ribbed. The dorsum, on the inside of the whorl, is slightly impressed, a result of the outermost whorl slightly enveloping the previous. The venter may be rounded or acute. The suture is simple, with a broad ventral saddle, broad lateral lobe, a dorsolateral saddle, and a moderately deep hidden dorsal lobe. Septal necks are usually short and do not form a continuous tube. The suture and siphuncle are characteristic of the family found in Europe and Western Australia.

If you fancy a read, check out the Treatise on Invertebrate Paleontology, Part L Ammonoidea; Geological Society of America and Univ of Kansas Press, 1964.

DINOSAURS OF THAILAND

This beautiful dinosaur track is from Kalasin Dinosaur Park in northeastern Thailand. 

Thailand boasts some of the finest Mesozoic trackways from five endemic dinosaur species.  

Since 1976, the Department of Mineral Resources with Thai-French Paleontological Project had continuously investigated the dinosaurs in the Phu Wiang mountains. The project found so many vertebrae, teeth, and footprints of the dinosaurs mainly from the sandstones of the Early Cretaceous Sao Khua Formation (about 130 million years old). These include sauropods and theropods ranging in size from adorable chickens to beasties up to 15 meters long. 

The Thai dinosaur record from the continental rocks of the Khorat Plateau is the best in Southeast Asia. The oldest footprints are those from small dinosaurs from the Middle to Late Jurassic Phra Wihan Formation. The most varied dinosaur assemblages come from the Late Jurassic Sao Khua Formation. Here we see the sauropods dominate the fossil beds interspersed with a variety of theropods. Large theropod footprints are known from the Early Cretaceous Phu Phan Formation. Theropods and the primitive ceratopsian Psittacosaurus occur in the Aptian-Albian Khok Kruat Formation. We find dinosaur material further north along the Mekong River region of Laos. Thai fossils show a close relationship to those found in China and Mongolia. 

If you'd like to go visit them, there is a rather nice display at the Phu Wiang Dinosaur Museum in the newly established Wiang Kao district about 80 kilometres to the west of the provincial capital of Khon Kaen. They have several species on display, including: Phuwiangosaurus sirindhornae, Siamosaurus suteethorni, Siamotyrannus isanensis, Kinnareemimus khonkaenensis, Compsognathus (awe, a wee vicious chicken...) and, of course, the Phu Wiang dinosaur footprints.

If you'd like to visit Kalasin Dinosaur Park, follow route 227 towards Lam Pao Dam and Dok Ket Beach. Instead of turning left towards the dam, continue up towards Sirindhorn Dinosaur Museum. You'll see it on your left about 5km before the museum. For some GPS help, pop this into Google Maps: Dinosaur Park, Ni Khom, Sahatsakhan District, Kalasin 46140, Thailand.

References: 

• Ingavat, R., Janvier, R., and Taquet, P. (1978) Decouverte en Thailande d'une portion de femur de dinosaure sauropode (Saurischia, Reptilia). C.R. Soc.Geol.France 3: 140-141
• Wickanet Songtham and Benja Sektheera (2006) Phuwiangosaurus sirindhornae Bangkok: Department of Mineral Resources: 100 pages
• Buffetaut, E., Suteethorn, V., and Tong, H. (2009) An earliest 'ostrich dinosaur' (Theropoda: Ornithomosauria) from the Early Cretaceous Sao Khua Formation of NE Thailand, pp. 229-243, in E. Buffetaut, G. Cuny, J. Le Loeuff, and V. Suteethorn (eds.), Late Palaeozoic and Mesozoic Ecosystem in SE Asia. Geological Society, London, Special Publication 315.

UPPER TRIASSIC LUNING FORMATION

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

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

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

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

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

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

After years of reading about the correlation between British Columbia and Nevada, I had the very great pleasure of walking through these same sections in October 2019 with members of the Vancouver Paleontological Society and Vancouver Island Palaeontological Society. It was with that same crew that I'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.

PARASAUROLOPHUS WALKERI OF ALBERTA

Holotype Specimen of P. walkeri, Royal Ontario Museum

Closer to home, we can find species of Parasaurolophus walkeri in the Dinosaur Park Formation of Alberta, Canada. 

The Dinosaur Park Formation is the uppermost member of the Belly River Group — also known as the Judith River Group, a major geologic unit in southern Alberta. 

It is an area rich in fossils. The formation contains dense concentrations of dinosaur skeletons, both articulated and disarticulated, often found with preserved remains of soft-tissues. Remains of other animals such as fish, turtles, and crocodilians, as well as plant remains, are also abundant. The formation has been named after Dinosaur Provincial Park, a UNESCO World Heritage Site where the formation is well-exposed in the badlands that flank the Red Deer River.

The Dinosaur Park Formation was deposited during the Campanian stage of the Late Cretaceous, between about 76.9 and 75.8 million years ago in what was an alluvial and coastal plain environment. It is bounded by the nonmarine Oldman Formation below and the marine Bearpaw Formation above.

The formation includes diverse and well-documented fauna including dinosaurs such as the horned Centrosaurus, Chasmosaurus, and Styracosaurus, fellow duckbills Gryposaurus and Corythosaurus, the mighty tyrannosaurid Gorgosaurus, and armoured Edmontonia, Euoplocephalus and Dyoplosaurus. 

Dinosaur Park Formation is interpreted as a low-relief setting of rivers and floodplains that became more swampy and influenced by marine conditions over time as the Western Interior Seaway transgressed westward. The climate was warmer than present-day Alberta, without frost, but with wetter and drier seasons. Conifers were apparently the dominant canopy plants, with an understory of ferns, tree ferns, and angiosperms.

Some of the less common hadrosaurs in the Dinosaur Park Formation of Dinosaur Provincial Park, such as Parasaurolophus, may represent the remains of individuals who died while migrating through the region. They might also have had a more upland habitat where they may have nested or fed. The presence of Parasaurolophus and Kritosaurus in northern latitude fossil sites may represent faunal exchange between otherwise distinct northern and southern biomes in Late Cretaceous North America. Both taxa are uncommon outside of the southern biome, where, along with Pentaceratops, they are predominant members of the fauna.

Photo: Holotype Specimen: The incomplete Parasaurolophus walkeri type specimen in the Royal Ontario Museum. Location: 43° 40′ 5.09″ N, 79° 23′ 40.59″ W. Shared by MissBossy.

HAREMS AND BLUEHEAD WRASSE

The Bluehead Wrasse, Thalassoma bifasciatum, live in coral reefs of the Atlantic Ocean. They range from the Caribbean Sea to the Gulf of Mexico. They are an interesting species in that they live in harems. 

When the male dies, one of the females transforms into a male and take control of the harem. It's a relatively quick takeover that happens just over a week. Taking control and exuding their maleness takes on a whole new meaning with Bluehead Wrasse. The males have a specific social system. Terminal phase males — which are the most aggressive and have the "highest" ranking among the males — and initial phase males — think horn-dog as they'll mate any chance they get in a larger group.  

When aggressive terminal phase males chase initial phase males, their colour changes to metallic green. Like flowers attracting bees, Bluehead Wrasse change colour to indicate their willingness to mate. When they are courting a female, Wrasse change to a soothing pinkish-grey (awe) and form black circles on their fins. It's the Wrassy equivalent to bring her a bouquet of flowers. Initial phase males, terminal phase males, and females all have the capability of reproducing. Tricky little bastards these Wrasse.

FLOUNDERS: BILATERAL SYMMETRY AND SHOOTING X'S

Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world. A few of their brethren call estuaries home. 

They undulate their bodies, darting from place to place, then resting on the bottom camouflaged by the muddy bottom. As a group, they belong to the families Achiropsettidae, Pleuronectidae, Paralichthyidae, and Bothidae (order Pleuronectiformes). 

Flounders are born with bilateral symmetry with an eye on each side. A few days later, they begin to lean to the side. The eye on their lower side slowly migrates so both eyes are on top. To make this work, their bodies undergo various changes in bones, nerve and muscular structure. Their undersides slowly lose colour — as who cares what colour your belly is if nobody's going to see it when you mate. But flounders face other pressures.

We complain about first world problems, but stressors in mating for our fishy friends are very real. If a genotypically female flounder is stressed during sexual development, she'll become phenotypically male — though he'll shoot all X's when it comes time to fertilize. 

CAMPANIAN OF HOKKAIDO

A very beautiful Lower Campanian block from Haroto, Hokkaido, Japan. This specimen contains an ancient undersea world at a glance.

The beautiful block you see here was prepared, photographed and is in the collections of José Juárez Ruiz. In it, you can see a lovely Pseudoxybeloceras (Parasolenoceras) soyaense (143 mm), Polyptychoceras jimboi (134 mm), Polyptychoceras sp. (114 mm), Gaudryceras mite (48 and 45 mm), Gaudryceras tenuiliratum (Hirano, 1978) at (48 and 20 mm), and a wee fragment of wood (69 mm).

Matsumoto published on the ammonites from the Campanian (Upper Cretaceous) of northern Hokkaido back in 1984, in the Palaeontological Society of Japan Special Series Papers, Number #27.

This was my first look at the glorious fauna from northern Japan. The species and preservation are truly outstanding. Since then, many of the Japanese palaeontologists have made their way over to Vancouver Island, to look at ammonites, inoceramids and coleoid jaws from the Nanaimo Group and compare them to the Japanese species.

Rick Ross and Pat Trask, both of Courtenay on Vancouver Island, collaborated with Dr. Kazushige Tanabe and Yoshinori Hikida of Japan, to produce a wonderful paper in the Journal of Paleontology, 82 (2), 2008, pp 398-408, on Late Cretaceous Octobrachiate Coleoid Lower Jaws from the North Pacific Regions. They compared eight well-preserved cephalopod jaws from Upper Cretaceous (Santonian and Campanian) deposits of Vancouver Island, Canada, and Hokkaido, Japan. Seven of these were from Santonian to lower Campanian strata of the Nanaimo Group in the northeastern region of Vancouver Island. The eighth specimen was from Santonian strata of the Yezo Group in the Nakagawa area, northern Hokkaido, Japan. 

While they were collaborating on identifying coleoid jaws from the Comox Valley, Rick was visited twice by Dr. Kazushige Tanabe who was joined by his colleague Akinori Takahashi. Takahashi is an expert on temporal species-diversity changes in Japanese Cretaceous inoceramid bivalves.

They had the very great pleasure of visiting many fossil sites and seeing personal and museum collections. If you'd like to read Matsumoto's paper, here is the link: http://www.palaeo-soc-japan.jp/download/SP/SP27.pdf  I have a pdf copy of the Coleoid paper from Rick. It has very nice photos and illustrations, including a drawing of the holotypes of Paleocirroteuthis haggerti n. gen. and Paleocirroteuithis pacifica.

Here's a link to one of Takahashi's papers: https://bioone.org/journals/paleontological-research/volume-9/issue-3/prpsj.9.217/Diversity-changes-in-Cretaceous-inoceramid-bivalves-of-Japan/10.2517/prpsj.9.217.short

MEET ANKYLORHIZA, APEX DOLPHIN

Back in the 1880s, a large fragmentary skull of an ancient toothed dolphin was described that would later be known as Ankylorhiza tiedemani. 

The newly named genus Ankylorhiza is derived from the Greek word "ankylo" meaning bound, stiff, or fused, and "rhiza", meaning root — meaning fused roots, and referring to the mostly single-rooted condition of the teeth — a surprisingly toothy grin for an early dolphin. 

We think of dolphins as the gentle, squeaky darlings of the ocean but back in the Oligocene, they were formidable predators. Picture a mug full of sharp teeth and a body designed for speed. Ankylorhiza tiedemani was the largest member of the Odontoceti, our toothed whale friends. 

More bits and pieces of this brute were unearthed in the 1970s and 1990s. We usually find just the skulls of our aquatic friends but the nearly complete skeleton that found its way to the Mace Brown Museum of Natural History at the College of Charleston included a well-preserved skull, the ribcage, most of the vertebral column and a lone flipper. These additional bits of the skeleton provided the information necessary to truly tease out this ancient tale. Together, the bones tell the story of a 4.8 m predator who would have diverged from baleen whales — but continued to evolve convergent similarities — about 35-36 million years ago. 

This beast of a dolphin hunted our ancient seas some 24 million years ago. He was a fast swimmer with a narrow tail stock, some added tail vertebra and a shorter humorous — upper arm bone — in his flippers. Some dolphins can exceed speeds of 50 km/h, a feat accomplished by thrusting the flukes while adjusting attack angle with their flippers. These movements are driven by robust axial musculature anchored to a relatively rigid torso consisting of numerous short vertebrae and controlled by hydrofoil-like flippers. 

Eocene skeletons of whales illustrate the transition from semiaquatic to aquatic locomotion, including the development of a fusiform body and reduction of hindlimbs, but the rarity of Oligocene whale skeletons has hampered efforts to understand the evolution of fluke-powered, but forelimb-controlled, locomotion. Modern whales and dolphins are superbly adapted for marine life, with tail flukes being a key innovation shared by all extant species. Did ancient dolphins have these modifications for speed? Most thought not. We have the benefit of modern species to make tentative comparisons but need ancient specimens to confirm the hypothesis. 

Kudos to Robert Boessnecker and team for their paper in the journal Current Biology. In it, they report a nearly complete skeleton of the extinct large dolphin Ankylorhiza tiedemani comb. n. from the Oligocene of South Carolina, previously known only from a partial rostrum. Its forelimb is intermediate in morphology between stem cetaceans and extant taxa, whereas its axial skeleton displays incipient rigidity at the base of the tail with a flexible lumbar region. 

The position of Ankylorhiza near the base of the odontocete radiation implies that several postcranial specializations of extant cetaceans, including a shortened humerus, narrow peduncle, and loss of radial tuberosity, evolved convergently in odontocetes and mysticetes. Craniodental morphology, tooth wear, torso vertebral morphology, and body size all suggest that Ankylorhiza was a macrophagous predator that could swim relatively fast, indicating that it was one of the few extinct cetaceans to occupy a niche similar to that of killer whales.

If you fancy a read, here's the reference:

Robert W. Boessenecker et al. Convergent Evolution of Swimming Adaptations in Modern Whales Revealed by a Large Macrophagous Dolphin from the Oligocene of South Carolina. Current Biology, published online July 9, 2020; doi: 10.1016/j.cub.2020.06.012

BOTTLENOSE DOLPHINS

These delightfully friendly and super smart fellows are Bottlenose dolphins. They are the most common members of the family Delphinidae, the family of oceanic dolphin. The genus is made up of three species: the bottlenose dolphin, Tursiops truncatus, the Indo-Pacific bottlenose dolphin, Tursiops aduncus, and the Burrunan dolphin, Tursiops australis. 

They are marine mammals who live in our world's oceans and breathe air at the surface, similar to humans. They have lungs, inhaling and exhaling through a blowhole at the top of their heads instead of a through their nose. They are social mammals and very playful. You may have seen them playing in the water, chasing boats or frolicking with one another. Humpback whales are fond of them and you'll sometimes see them hanging out together. 

Bottlenose dolphins are also choosy about who they spend time with. While they stick close to Mamma for the first three years of their lives, they like to spend time in close social groups with their friends. Males tend to choose to hang out with males resting, rubbing up against one another and being playful. Females tend to favour their female friends and their chosen quality time activity is often foraging for fish. They still move freely amongst all the members of their pod but do have favourites.

Dolphins are quite vocal, making a lot of interesting noises in the water. Dolphins engage with the world around them through sound. They squeak, squawk and use body language — leaping from the water while snapping their jaws and slapping their tails on the surface — to express themselves. 

They love to blow bubbles and will swim right up to you for a kiss and cuddle. I swam with dolphins many years ago down in the Bahamas. They are pretty fast in the water, reaching speeds of up to 35 kilometres per hour. Each individual dolphin has a signature sound, a whistle that is uniquely theirs. Dolphins use this whistle to tell one of their friends and family members from another.

CERATITES NODOSUS

A lovely beast of an ammonite, Cératites nodosus, from the collections of the deeply awesome Ange Mirabet. This species is an extinct genus of nektonic marine carnivore from limestone deposits near Alsace on the Rhine River plain of northeastern France.

You can see the nice ceratitic suture pattern on this specimen with his smooth lobes and frilly saddles. The sutures would have increased the strength of the shell and allowed Ceratites (de Haan, 1825) to dive deeper, bearing the additional pressure of the sea in search of food.

Ammonite shells are made up predominantly of calcium carbonate in the form of aragonite and proteinaceous organic matrix or conchiolin arranged in layers: a thin outer prismatic layer, a nacreous layer and an inner lining of prismatic habitat. While their outer shells are generally aragonite, aptychus — those hard shelly plates you see — are distinct as they are composed of calcite.

These ammonites lived in open shallow, to subtidal and basinal environments some 247 to 221 million years ago. We've found them, thus far, in just over forty collections from nearly ninety fossil deposits around the globe. Fossils of species have been found in the Triassic of Austria, Canada, China, France, Germany, Hungary, India, Israel, Italy, Pakistan, Poland, Russia, Thailand, Turkey and the United States.

The parent taxon is Ceratitinae according to E. T. Tozer 1981. That's our own Tim Tozer, one of the great knights-errant of the Triassic timescale. Born a Brit but spent his life exploring the wilds of Canada and the Arctic Archipelago. It was Tim Tozer and Norm Silberling who published the classic milestones of the Triassic timescale, "Biostratigraphic Classification of the Marine Triassic in North America, Geological Society of America, Special Paper 110." The Global Triassic: Bulletin 41 from the New Mexico Museum of Natural History and Science by Lucas and Spielmann honours them in their work. Collection of Ange Mirabet, Strasbourg, France.

OH, CORONICERAS!

This Jurassic ammonite is from an all but inaccessible site in Sayward, Bonanza Group, Vancouver Island. He's a Coroniceras with a truly marvellous keel.

By the time these ammonites were being buried in sediment, Wrangellia, the predominately volcanic terrane that now forms Vancouver Island and the Queen Charlotte Islands, had made its way to the northern mid-latitudes.

Within the basal part of the sequence, sedimentary beds are found interbedded with lapilli and crystal-tuffs. Here you'll see maroon tuffaceous sandstone, orange-grey sandstone, granule sandstone and conglomerate. Within them we find ammonites nestled in with gastropods and pelecypods. 

While the fossiliferous outcrop is quite small, the Bonanza group is much larger, estimated to be at least 1000 metres thick. The site is quite small and in an active logging area, so the window to collect was limited. The drive up the mountain was thrilling as there had just been heavy rains and the road was washed out and narrowed until it was barely the width of our wheelbase and then narrowed further to be just shy of the width of the vehicle — thrilling, to say the least. So scary that my passengers all got out as there was a high probability of going head-first over the edge. I navigating by some handwritten field notes and a wee map on a paper napkin that should have read, "park at the bottom and hike up." Nope. We didn't park at the bottom and were halfway up the mountain before the road narrowed out. Too narrow to turn around, so the only way was up. 

Coroniceras with a sweet, sweet keel

Graham Beard from Qualicum Beach was the fellow who showed me the site and drew the wee map for me. I cannot recall everyone on the trip, but Perry Poon was there — he shot a video of the drive up that he described as thrilling. I've never seen it but would like to one day — and so was Patricia Coutts with her lovely Doberman. 

She and I had just done a trip up to Goldbridge where the cliff we were on had turned into a landslide into a ravine so she was feeling understandably cautious about the power of Mother Nature. Picture the angle, the hood of my jeep riding high and hiding what remained of the road beneath and a lovely stick shift that made you roll backwards a wee bit with every move to put it into gear. So, without being able to see the very narrow path beneath, I had to just keep going. Both Perry and Patricia helped with filling in the potholes so my tires would have something to grip. I bent the frame on the jeep heading up and had some explaining to do when I returned it to the car rental place. 

In the end, we found what we were looking for. Memekay yields a mix of ammonites, gastropods and bivalves. Many of them poorly preserved. It was a hell of a ride but well worth the effort as we found some great fossils and with them more information on the palaeontology and geology of Vancouver Island. Just look at the keel on this beauty.

SPOTTED CLEANER SHRIMP: FISH WASH

"Wash that for you, sir?" If you were a fish living in the warm turquoise waters off the coast of Bonaire in the southern Caribbean Sea, you may not hear those words, but you'd see the shrimp sign language equivalent. It seems Periclimenes yucatanicus or the Spotted Cleaner Shrimp are doing a booming business in the local reefs by setting up a Fish Wash service.

That's right, a Fish Wash. You'd be hard-pressed to find a terrestrial Molly Maid with two opposable thumbs as studious and hardworking as this wee marine beauty. You'll find them each day cleaning and snacking on a host of parasites. As many as twenty to thirty shrimp gather together to assemble a  highly-efficient marine cleaning station. They're even open to partnerships and mergers, partnering up with Cleaner Wrasse, or cleaner fish, for larger, high-end clients.

Spotted cleaner shrimp are about 2.5 cm long and have a delightful transparent body with telltale white and brown spots. Their legs, or chelae, are striped in purple, white and red. They live about 24 metres (or 79 ft) down on the seafloor in many of our planet's most beautiful waters. Aside from the Caribbean, they also enjoy setting up shop in the Bahamas, southern Florida and live as far south as Panama and Columbia. They are carnivorous crustaceans in the family, Palaemonidae.

This quiet marine mogul is turning out to be one of the ocean's top entrepreneurs. Keeping its host and diet clean and green, the spotted shrimp hooks up with the locals, in this case, local sea anemones and sets up a fish wash. Picture a car wash but without the noise and teenage boys. The signage posted is the shrimps' natural colouring which attracts fish from around the reefs. They sway back and forth to indicate that they are open for business.

Wash on, wash off.

Once within reach, the shrimp cleans the surface of the fish, giving the fish a buff and the shrimp its daily feed. This is good news for the shrimp, especially this time of year as they breed and brood their eggs in summer. 

After hatching, the larvae pass through a series of sadly, tasty planktonic stages before setting up a fish wash of their own. These cuties form a solid base for the oceanic food chain. Once they are older, they gain some protection from being eaten by their clients by a special signalling system that essentially shouts, "just here cooperation not as food." Here's to Periclimenes for keeping up the family business.

HETEROPTERAN OF THE GREEN RIVER

A delightful Heteropteran collected this past year by Jim Barkley from Eocene exposures of the Green River Formation of Western Colorado. The specimen looks like he's been brushed as ink across rough watercolour paper. The Green River Formation boasts very fine detail in the preservation of the fossils found here. 

This was once the bottom of an extensive series of Eocene lakes. The fossils record which species called this area home and what the climate was like they lived in some 50 million years ago. It was warmer and wetter than that area today. Think temperate to sub-tropical, with temperatures ranging from 15 to 20 degrees Celsius. The Green River Formation has layers and layers of fine-grain sedimentary rock particularly abundant in beautifully preserved fossil fish, eleven species of reptiles including a 13.5ft crocodile, an armadillo-like mammal, Brachianodon westorum, bats, birds and other freshwater aquatic goodies.

CRASPEDITES OF RUSSIA

This stunning block with the black matrix holds two lovely ammonoids found near the town of Rybinsk in the Yaroslavl region of Russia just northeast of Moscow. Interestingly, both Miss Russia 1998 and the first women in space hail from here, Anna Malova and Valentina Tereshkova respectively. Beyond bright, beautiful women, the area is home to some of the most interesting fossil specimens on the globe. 

You can see two of them here. The lovely larger ammonoid with the oil-in-water colouring is Craspedites okensis (d'Orbigny, 1945). Craspedites is an ammonoid cephalopod included in the Perisphinctaceae that lived during the Late Jurassic and Early Cretaceous, found in Canada, Greenland, Poland and Russia.

The genus Craspedites was first described by Aleksei Petrovich Pavlow in 1892. It is characterized by a small — up to about 5 cm in diameter — smooth, involute shell with simple ammonitic sutures. The whorl section is rounded with a smooth centre and small umbilicus exposing the dorsal portion of the inner whorls. Craspedites was thought to be restricted to the Upper Jurassic Tithonian until the discovery of a new species, C. sachsi, from the Berriasian of Russia (A. E. Igolnikov, 2012) named in honour of palaeontologist V.N. Sachs.

The smaller ammonite you see on the bottom of this block is Craspedites sp. from Jurassic deposits of the Volgian Stage, the zone subditus — 150 - 140.2 million years old. The photo credit belongs to the deeply awesome Emil Black. This block is in his personal collection. If you're interested in learning more about the ammonites from Russia, there is a publication from Ernst Gerold Westermann you may want to read, The Jurassic Ammonite Zones of the Soviet Union, Issue 223.

A. E. Igolnikov (2012). Craspedites (Vitaliites?) sachsi, a New Boreal Berriasian ammonite species of the North of Eastern Siberia (Nordvik Peninsula) Paleontological Journal. 46 (1): 12–15. Here's the link if you'd like to read it: 

https://web.archive.org/web/20131017012543/http://rogov.zwz.ru/Igolnikov%2C2012_Craspedites_sachsi_en.pdf

AMMONITES OF THE VOLGA REGION

The Heteromorph, Jaubertites (Audouliceras) renauxianum

A stunningly beautiful example of the heteromorph ammonite Jaubertites (Audouliceras) renauxianum (d'Orbigny, 1842) from the Volga region in Russia. The Volga region encompasses the drainage basin of the Volga River, the longest river in Europe, in central and southern European Russia. The area is well-known for the beautiful fossil assemblages found here.

These magnificent Jaubertites (Audouliceras) renauxianum heteromorph ammonites are often composites — built with exceptional artful skill from various partial specimens.

We sometimes see them cut in two symmetrical parts and glued into a matrix then doctored up a bit for sale. The practice is frowned upon both scientifically and commercially but continues as does the demand for these exceptional specimens. This beauty is in the collection of José Juárez Ruiz and is complete with some minor restorations. I love these chunky Jaubertites and particularly appreciate the beautiful oil in water colouring in the nacre.

The second photo here shows a lovely busy block of ammonites with Deshayesites volgensis (Sasonova, 1958), and Aconeceras (Sinzovia) trautscholdi (Sinzow. 1870) from Lower Cretaceous, Aptian, (120 - 112 MYA), deposits in the v. Shilovka, Ulyanovsk Region of Russia. This beauty is in the collections of Emil Black. While Emil has counselled me that there are some fundamental challenges with the interpretation of these faunal groups, I will share what is available from the current literature.

Aptian deposits near the Volga River between Ul'yanovsk and Saratov have been studied for more than a century. The area produces some of the most beautiful and sought after ammonite specimens in the world. I've never had the pleasure of collecting in this region but follow the literature and local collectors with enthusiastic interest. Looking at the specimens from here, I'm sure you can appreciate why.

Deshayesites volgensis & Aconeceras trautscholdi

The age of lower Aptian deposits was traditionally established based on changing ammonite assemblages of the family Deshayesitidae. The beauty you see to the right with the lovely ribbing and coloured from cream through to pink and blue is the hallmark species of this area.

But Deshayesitidae are not the only specimens found here. The vast array of heteromorphic ammonites  —  the Ancyloceratidae, inhabitants of relatively deep basins, has made it possible to propose a new scheme of ammonoid zonation in the lower Aptian epipelagic deposits of the Russian plate.

Many of the identified ancyloceratids were established here for the first time. The analysis of coexisting deshayesitids and heteromorphs enables a correlation of stratigraphic schemes for the monomorphic Deshayesitidae and heteromorphic Ancyloceratidae.

The described generic taxa and species are Volgoceratoides I. Michailova et Baraboshkin, gen. nov., V. schilovkensis I. Michailova et Baraboshkin, sp. nov., Koeneniceras I. Michailova et Baraboshkin, gen. nov., K. tenuiplicatum (von Koenen, 1902), K. rareplicatum I. Michailova et Baraboshkin, sp. nov.

In some sections of the Saratov Volga area, specifically in the central part of the Russian Platform, we find both offshore and nearshore lithofacies of the epicontinental Middle Russian Sea. Here we see simultaneous changes in ammonite and belemnite successions that speak to an environmental shift. The significant influence of anoxic events on faunal turnovers in marine communities is well-established. However, many studies are focused on the impact of anoxic conditions on benthic organisms, not on the hunter-gatherers living higher up in the sea column and food chain. For this reason, coeval changes in pelagic cephalopod assemblages remain relatively poorly studied and marginally understood.

Belemnites, represented by the late members of the family Oxyteuthididae, are common in the interval directly preceding the anoxic event, but totally disappear with the onset of the black shale deposition. We see a reduction in the shell size of the Deshayesites ammonites across the mudstone – black shale boundary (maximum shell diameter of adults reduces from ∼20 cm to 7–8 cm).

Some other ammonites become numerous (Sinzovia) within the black shale interval or show the first occurrence in it (Koeneniceras and Volgoceratoides). The diminishing of Deshayesites shell size during the early Aptian OAE may have been caused by palaeoenvironmental factors such as progressive warming and regional input of brackish water.

The significant influence of anoxic events on faunal turnovers in marine communities is well-established. However, many studies are focused on the impact of anoxic conditions on benthic organisms, not on the hunter-gatherers living higher up in the sea column. This means that coeval changes in pelagic cephalopod assemblages remain relatively poorly understood.

Photo: Jaubertites (Audouliceras) renauxianum (d'Orbigny, 1842) collection of José Juárez Ruiz.
Photo: Deshayesites volgensis (Sasonova, 1958), and Aconeceras (Sinzovia) trautscholdi (Sinzow. 1870) collections of Emil Black. The diameter on the Deshayesites shown here is 70 mm.

Rogov, Mikhail & Shchepetova, Elena & Ippolitov, Alexei & Seltser, Vladimir & Mironenko, Aleksandr & Pokrovsky, Boris & Desai, Bhawanisingh. (2019). Response of cephalopod communities on abrupt environmental changes during the early Aptian OAE1a in the Middle Russian Sea. Cretaceous Research. 10.1016/j.cretres.2019.01.007.

E. Yu. Baraboshkin and I. A. Mikhailova. New Stratigraphic Scheme of the Lower Aptian in the Volga River Middle Courses. Stratigraphy arid Geological Correlation, Vol 10, No 6, 2002, pp 603-626 Translated from Stratigrafiy a Geologicheskaya Korrelyatsiya, Vol 10, No 6, 2002, pp 82-105

HETTANGIAN: TETHYAN AFFINITY

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.

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

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