Saturday 16 February 2019
Friday 15 February 2019
GLORIOUS SHARK OF CHUBUT
These big beasties lived during Oligocene, Miocene, and Pliocene, 28-5 million years ago. This fellow is considered to be a close relative of the famous prehistoric mega-toothed shark, C. megalodon, although the classification of this species is still disputed.
Swiss naturalist Louis Agassiz first identified this shark as a species of Carcharodon in 1843. In 1906, Ameghino renamed this shark as C. chubutensis. In 1964, shark researcher, L. S. Glikman recognized the transition of Otodus obliquus to C. auriculatus. In 1987, shark researcher, H. Cappetta reorganized the C. auriculatus - C. megalodon lineage and placed all related mega-toothed sharks along with this species in the genus Carcharocles. At long last, the complete Otodus obliquus to C. megalodon progression became clear and has since gained the acceptance of his peers. The specimen you see here is in the Geological Museum in Lisbon. Photo credit: Luis Lima.
Tuesday 12 February 2019
Sunday 10 February 2019
BRITISH COLUMBIAN ICE AGE
In the southern Interior, ice built up first in the northern Selkirk Mountains, then slowly flowed down into the valleys. Once the valleys were filled, the depth of the ice increased until it began to climb to the highlands and finally covered most of the Interior of British Columbia.
Between ice advances, there were times when the Kamloops area was ice free and the climate warm and hospitable. Glacial ice was believed to have initiated its most recent retreat from the South Thompson area around 11,000 to 12,000 years ago, but salmon remains from 18,000 years ago suggest that it may have actually began its northwest decline much earlier and indicating a much warmer climate in the Interior than archaeologists or geologists had originally estimated.
Saturday 9 February 2019
CAMPANIAN NAUTILUS
Friday 8 February 2019
SUMAS FOSSIL SLIDE SITE
George Mustoe, Sumas Fossil Slide Site |
In 2009, there was a large downpour that hit Washington State causing massive slides. The blocks you see here all came crashing down on the hillside. Once the skies cleared, hikers found plant impressions in the rock and alerted the local paleo community. I was invited to tag along on a trip to photograph the site while George Mustoe took moulds of the palm trunks and trackways. The slide site at Sumas Mountain revealed many large exposures of fossil plants. Some exposures were 10 feet across. There was great excitement at seeing shorebird tracks and trackways of the large flightless bird Diatryma.
Thursday 7 February 2019
WASHINGTON FOSSIL FIELD TRIP
Sumas Slide Site, Sumas, Washington State |
The shifting continues, subtling changing the landscape like a breath. We only notice when pockets of resistance manifest as earthquakes, some newsworthy, some all but unnoticed. For now, the more extreme movement has subsided laterally and continues vertically, pushing California towards the North Pole. Hello Baja-BC.
The upthrusting of plates moves our mountain ranges skyward – the path of least resistance. And it is this dynamic movement that's created the landscape we see today.
The 3,000 meters of stratigraphic section on Chuckanut Drive spans an age range of just a few million years. The lower part is late Paleocene with a radiometric age of around 56 million years. The upper part of the section is early Eocene. The fossils found here lived and died very close to where they are now but in a much warmer, wetter, swampy setting.
The exposures of the Chuckanut Formation were once part of a vast river delta; imagine, if you will, the bayou country of the Lower Mississippi. The siltstones, sandstones, mudstones and conglomerates of this formation were laid down during a time of luxuriant plant growth in the subtropical flood plain that covered much of the Pacific Northwest.
This ancient wetland provided ideal conditions to preserve the many trees, shrubs and plants that thrived here giving us a lot of information about climate, temperature, the water cycle and humidity of the region.
The Chuckanut flora is made up predominantly of plants whose modern relatives live in tropical areas such as Mexico and Central America. While less abundant, evidence of the animals that called this ancient swamp home are also found here. Rare bird, reptile, and mammal tracks have been immortalized in the outcrops of the Chuckanut Formation.
Tracks of a type of archaic mammal of the Orders Pantodonta or Dinocerata (blunt foot herbivores), footprints from a small shorebird, and tracks from an early equid or webbed bird track give evidence to the vertebrates that inhabited the swamps, lakes and river ways of the Pacific Northwest 50 million years ago.
Fossil mammals and bird trackways from Washington cause great excitement. The movement of these celebrity vertebrates was captured in the soft mud on the banks of a river, one of the only depositional environments favorable for track preservation.
Hence the terrestrial paleontological record of Washington State at sites like Chuckanut and Racehorse Creek (U-Pb 53 Ma.) is primarily made up of plant material with some wonderfully enticing mammal, shorebird and large Diatryma bird tracks to shake things up.
Wednesday 6 February 2019
YORKSHIRE COAST AMMONITE
Tuesday 5 February 2019
Monday 4 February 2019
MASSIVE BOULDERS: SUMAS SLIDE SITE
Sumas Fossil Slide Site |
Once the skies cleared, hikers found plant impressions in the rock and alerted the local paleo community. I was invited to tag along on a trip to photograph the site while George Mustoe took molds of the palm trunks and trackways.
The slide site at Sumas Mountain revealed many large exposures of fossil plants. Some exposures were 10 feet across. There was great excitement at seeing shorebird tracks and trackways of the large flightless bird Diatryma.
Sunday 3 February 2019
FORTUNE FAVORS THE BOLD
Audaces fortuna iuvat |
Bear cubs are known for being playful and all together too curious. They usually stick pretty close to Mamma but sometimes an intriguing opportunity for discovery will cross their path and entice them to slip away just for a few minutes to check it out.
The karma gods were good to this wee one. Nobody was skunked in this quest for exploration, though not for lack of trying.
Saturday 2 February 2019
LASALLE LIMESTONE CRINOIDS
Friday 1 February 2019
Thursday 31 January 2019
APODEROCERAS, YOUR GRACE
Apoderoceras is, in fact, a wonderful example of sexual dimorphism within ammonites as the macroconch (putative female) shell grew to diameters in excess of 40 cm – many times larger than the diameters of the microconch (putative male) shell. Apoderoceras has been found in the Lower Jurassic of Argentina, Hungary, Italy, Portugal, and most of North-West and central Europe, including as this one is, the United Kingdom. She was found on the beaches of Charmouth in West Dorset, then prepped expertly by the lovely and talented Lizzie Hingley.
Neither Apoderoceras nor Bifericeras donovani are strictly index fossils for the Taylori subzone, the index being Phricodoceras taylori. Note that Bifericeras is typical of the earlier Oxynotum Zone, and ‘Bifericeras’ donovani is doubtfully attributable to the genus.
The International Commission on Stratigraphy (ICS) has assigned the First Appearance Datum of genus Apoderocerasas and of Bifericeras donovani the defining biological marker for the start of the Pliensbachian Stage of the Jurassic, 190.8 ± 1.0 million years ago. As the brilliant Murray Edmunds points out, this lovely large specimen (macroconch) of Apoderoceras is likely a female. Her larger body perfected for egg production.
Cat's Paw Suture Walls of Apoderoceras |
The Pacific ammonite Andicoeloceras, known from Chile, appears quite closely related and may be ancestral, but the time correlation of Pacific and NW European ammonite faunas is challenging. Even if Andicoeloceras is ancestral to Apoderoceras, no other preceding ammonites attributable to Coeloceratidae are known. (Maybe there are clues in the Lias of Canada?) Apoderoceras remains present in NW Europe throughout the Taylori Subzone, showing endemic evolution.
It becomes progressively more inflated during this interval of time, the adult ribs more distant, and there is evidence that the diameter of the macroconch evolved to become larger. At the end of the Taylori Subzone, Apoderoceras disappeared as suddenly as it appeared in the region, and ammonite faunas of the remaining Jamesoni Zone are dominated by the Platypleuroceras–Uptonia lineage, generally assigned (but erroneously, IMO!) to the Family Polymorphitidae.
In the NW European Taylori Subzone, Apoderoceras is accompanied (as well as by the Eoderoceratid, B. donovani, which is only documented from the Yorkshire coast, although I know of examples from Northern Ireland) by the oxycones Radstockiceras (quite common) and Oxynoticeras (very rare), the late Schlotheimid, Phricoderoceras (uncommon: note P. taylori is a microconch, and P. lamellosum the macroconch), and the Eoderoceratid, Tetraspidoceras (very rare).
Thank you to Murray Edmunds for his advice, guidance and corrections as we explore Apoderoceras and the ammonite faunas of the Pacific and NW Europe. You are deeply awesome, my friend!
Check out Murray’s Research Gate site for more interesting tidbits!
https://www.researchgate.net/profile/Murray_Edmunds; the photo above of the Cat's Paw Sutures of an Apoderoceras from Dorset are from the lovely Simon Guscott. Appreciate you!
Wednesday 30 January 2019
DINOGORGON: TERROR OF THE LATE PERMIAN
Dinogorgon Rubidgei / Photo: Jonathan Blair / Corbis |
For many years, we've believed that these mighty hunters reigned and died out in less than a million years. Dinogorgon is meant to have vanished during one of the greatest mass extinction events on the planet, the Permian Extinction. We've recorded five mass extinction events in our humble 4.6 billion year history. The event from the Permian wiped our about nine of every ten plant and animal species on the planet. New fossil evidence suggests that there were actually two mass extinctions during this time, with a sixth event happening around 260 million years ago.
Tuesday 29 January 2019
UPPER CRETACEOUS NANAIMO GROUP
Upper Cretaceous Nanaimo Group / Denman Island |
This succession has been the focus of many paleomagnetic, isotope geochemistry, paleontology, and sedimentology studies with the aim of untangling the tectonic history and paleolatitude of the Insular Superterrane during the Nanaimo Group deposition some 90 to 65 million years ago.
One would think that these research papers would support each other in terms of that deposition. Much to our chagrin, we're still working through the strata to define both the formal stratigraphy, untangle if it was deposited in single or multiple basins and match it up with local and regional correlations.
The upper two-thirds of the succession is continuously and well exposed on Denman and Hornby islands and represents the best example of this part of the succession in the northern half of what we consider the single Nanaimo Basin. This area includes the previously only informally defined type areas for the Geoffrey and Spray formations, defined here formally for the first time with type sections and detailed descriptions. New interpretations of the geology of these islands demonstrate that previously interpreted major faults do not exist, resulting in stratigraphic and age controls that are both different and simpler than previously interpreted. The redefined stratigraphy of the northern part of the basin is remarkably similar to that of southern areas in both type and age, affirming both a single basin evolution and a single stratigraphic nomenclature.
Monday 28 January 2019
Saturday 26 January 2019
Friday 25 January 2019
ICHTHYOSAUR VERTEBRAE AND RIBS
Ichthyosaurs are an extinct order of marine reptiles from the Mesozoic era. They evolved from land-dwelling, lung-breathing reptiles who returned to our ancient seas and evolved into the fish-shaped creatures we find in the fossil record today.
They were visibly dolphin-like in appearance but seem to share some other qualities as well. These lovelies were warm-blooded and used their coloration as camouflage. The smaller of their lineage to avoid being eaten and the larger to avoid being seen by prey. Ichthyosaurs also had insulating blubber, a lovely adaptation to keep them warm in cold seas.
Over time, their limbs fully transformed into flippers, sometimes containing a very large number of digits and phalanges. Their flippers tell us they were entirely aquatic as they were not well-designed for use on land. It was their flippers that first gave us the clue that they gave birth to live young; a hypothesis later confirmed by fossil embryo and wee baby ichy specimens.
We find their fossil remains in outcrops spanning from the mid-Cretaceous to the earliest Triassic. As we look through the fossils, we see a slow evolution in body design moving towards that enjoyed by dolphins and tuna by the Upper Triassic, albeit with a narrower, more pointed snout.
During the early Triassic period, ichthyosaurs evolved from a group of unidentified land reptiles. They were particularly abundant in the later Triassic and early Jurassic periods before being replaced as a premier aquatic predator by another marine reptilian group, the Plesiosauria, in the later Jurassic and Cretaceous periods. The block you see here is from Middle Triassic (Anisian/Ladinian) outcrops in the West Humboldt Mountains, Nevada.
Thursday 24 January 2019
Wednesday 23 January 2019
FOSSIL CROCODILE
Fossil Crocodile, Lisbon Natural History Museum. Photo: Luis Lima |
This specimen is housed in the Geological Museum of Lisbon. The museum was built in 1857 and is home to beautiful paleontology, archaeology and mineral specimens.
Tuesday 22 January 2019
Monday 21 January 2019
CHAMPAGNE-ARDENNE HOPLITES
L'Albien or Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It was named after Alba, the Latin name for the River Aube, a tributary of the Seine that flows through the Champagne-Ardenne region of northwestern France.
The Albian is the youngest or uppermost subdivision of the Lower Cretaceous, approximately 113.0 ± 1.0 Ma to 100.5 ± 0.9 Ma (million years ago).
At the time that this fellow was swimming in our oceans, ankylosaurs were strolling about Mongolia and stomping through the foliage in Utah, Kansas and Texas. Bony fish were swimming over what would become the strata making up Canada, the Czech Republic and Australia. Cartilaginous fish were prowling the western interior seaway of North America and a strange extinct herbivorous mammal, Eobaatar, was snuffling through Mongolia, Spain and England. Interesting times.
Hoplites maritimus / Hoplites rudis |
Hoplites shells have compressed, rectangular and trapezoidal whorl sections. They have pronounced umbilical bullae from which their prominent ribs branch out. The ends of the ribs can be both alternate or opposite. Some species have zigzagging ribs and these usually end thickened or raised into ventrolateral tubercules.
Ammonites were predatory, squid-like creatures that lived inside coil-shaped shells. Like other cephalopods, ammonites had sharp, beaklike jaws inside a ring of tentacles that extended from their shells to snare prey such as small fish and crustaceans. Some ammonites grew more than three feet (one meter) across — possible snack food for the giant mosasaur Tylosaurus.
Ammonites constantly built new shell as they grew, but only lived in the outer chamber. They scooted through the warm, shallow seas by squirting jets of water from their bodies. A thin, tubelike structure called a siphuncle reached into the interior chambers to pump and siphon air and helped them move through the water.
Ammonites first appeared about 240 million years ago, though they descended from straight-shelled cephalopods called bacrites that date back to the Devonian, about 415 million years ago. They were prolific breeders, lived in schools, and are among the most abundant fossils found today. They went extinct with the dinosaurs 65 million years ago. Scientists use the various shapes and sizes of ammonite shells that appeared and disappeared through the ages to date other fossils.
Hoplites sp. from the Early Cretaceous of Dorset, UK |
Ammonites began life very tiny, less than 1mm in diameter, and were vulnerable to attack from predators. They fed on plankton and quickly assumed a strong protective outer shell. They also grew quickly with the females growing up to 400% larger than the males; because they needed the larger shell for egg production. Most ammonites only lived for two years. Some lived longer becoming very large. The largest ever found was in Germany (6.5 feet in diameter).
Ammonites lived in shallow waters of 100 meters or less. They moved through the water by jet propulsion expelling water through a funnel-like opening to propel themselves in the opposite direction. They were predators (cephalopods) feeding on most living marine life including mollusks, fish even other cephalopods. Ammonites would silently stalk their prey then quickly extend their tentacles to grab it. When caught the prey would be devoured by the Ammonites' jaws located at the base of the tentacles between the eyes.
Hoplites dentalus, from Albian deposits near Troyes, France |
As the ammonite grew, it added new and larger chambers to the opened end of the shell. A thin living tube called a siphuncle passed through the septa, extending from the body to the empty shell chambers.
This allowed the ammonite to empty water out of the shell chambers by hyperosmotic active transport process. This process controlled the buoyancy of the ammonite's shell.
First Photo: Hoplites Bennettiana from near Troyes, France. Collection de Christophe Marot
Second Photo: Top: Hoplites maritimus from Sussex, UK. Bottom: Hoplites rudis from near Troyes, France. Collection of Mark O'Dell
Third Photo: Hoplites sp. from the Early Cretaceous of Dorset, UK. Natural Selection Fossils
Fourth Photo: Hoplites dentalus from Albian deposits near Troyes, France. Collection of Stéphane Rolland.
Wright, C. W. (1996). Treatise on Invertebrate Paleontology, Part L, Mollusca 4: Cretaceous Ammonoidea (with contributions by JH Calloman (sic) and MK Howarth). Geological Survey of America and University of Kansas, Boulder, Colorado, and Lawrence, Kansas, 362.
Amédro, F., Matrion, B., Magniez-Jannin, F., & Touch, R. (2014). La limite Albien inférieur-Albien moyen dans l’Albien type de l’Aube (France): ammonites, foraminifères, séquences. Revue de Paléobiologie, 33(1), 159-279.
Sunday 20 January 2019
OSTEOLOGIE DU MEGATHERIUM
Jean Louis Denis was the engraver who created this lovely plate. We have Leonard C. Bruno to thank for access to this image. He took black and white photos of the plate and published them in 1987 to the Library of Congress with full open access. Illus. in: Recherches sur les ossemens fossiles / Georges Cuvier. Third ed. Paris: G. Dufour et E. d'Ocagne, 1825, pl. 16. Published in: The tradition of science / Leonard C. Bruno. Washington, D.C. : Library of Congress, 1987, p. 215.
Saturday 19 January 2019
SLOTHS AND AVOCADOS
The megaterios were large terrestrial sloths belonging to the group, Xenarthra. These herbivores inhabited large areas of land on the American continent. Their powerful skeleton enabled them to stand on their hind legs to reach leaves high in the trees, a huge advantage given the calories needed to be consumed each day to maintain their large size.
Avocados were one of the food preferences of our dear Giant ground sloths. They ate then pooped them out, spreading the pits far and wide. The next time you enjoy avocado toast, thank this large beastie. One of his ancestors may have had a hand (or butt) in your meal.
In 1788, Bru assembled the skeleton as you see it here. It is exhibited at the Museo Nacional De Ciencias Naturales in Madrid, Spain, in its original configuration for historic value. If you look closely, you'll see it is not anatomically correct. But all good paleontology is teamwork. Based upon the drawings of Juan Bautista Bru, George Cuvier used this specimen to describe the species for the very first time.
Friday 18 January 2019
Thursday 17 January 2019
ZENAPIS PODOLICA
Zenaspis is an extinct genus of jawless fish which existed during the early Devonian period. Due to it being jawless, Zenaspis was probably a bottom feeder.
The lovely 420 million-year-old plate you see here is from Podolia or Podilia, a historic region in Eastern Europe, located in the west-central and south-western parts of Ukraine, in northeastern Moldova. Podolia is the only region in Ukraine where Lower Devonian remains of ichthyofauna can be found near the surface.
For the past 150 years, vertebrate fossils have been found in more than 90 localities situated in outcrops along banks of the Dniester River and its northern tributaries, and in sandstone quarries. At present faunal list of Early Devonian agnathans and fishes from Podolia number 72 species, including 8 Thelodonti, 39 Heterostraci, 19 Osteostraci, 4 Placodermi, 1 Acanthodii, and 1 Holocephali (Voichyshyn 2001a, modified).
In Podolia, Lower Devonian redbeds strata (the Old Red Formation or Dniester Series) can be found up to 1800 m thick and range from Lochkovian to Eifelian in age (Narbutas 1984; Drygant 2000, 2003). In the lower part (Ustechko and Khmeleva members of the Dniester Series) they consist of multicoloured, mainly red, fine-grained cross-bedded massive quartz sandstones and siltstones with seams of argillites (Drygant 2000).
We see fossils beds of Zenaspis in the early Devonian of Western Europe. Both Zenaspis pagei and Zenaspis poweri can be found up to 25 centimetres long in Devonian outcrops of Scotland.
Reference: Voichyshyn, V. 2006. New osteostracans from the Lower Devonian terrigenous deposits of Podolia, Ukraine. Acta Palaeontologica Polonica 51 (1): 131–142. Photo care of Fossilero Fisherman.
Wednesday 16 January 2019
THE LAST ICE AGE
Tuesday 15 January 2019
FIRST ITALIAN FOSSILS OF AGRIOTHERIUM
Agriotherium / Short-Faced Bear |
Agriotherium is one of the largest of the mighty carnivores that lived in Europe back in the Pleistocene. They weighed as much as 900 kilos (almost 2,000 lbs) and grew up to 2.5 meters tall. These ancient bears roamed prehistoric Italy amid a humid and temperate climate, competing for food resources with some of our ancestors as they only becoming extinct 2.6 million years ago.
Monday 14 January 2019
CAMBRIAN SEA ANEMONE
Sunday 13 January 2019
PREHISTORIC BUGS: WANNERIA DUNNAE
Saturday 12 January 2019
Friday 11 January 2019
IRIDESCENT EUHOPLITES
Its shell is covered in the lovely lumps and bumps we associate with the genus. The function of these adornments are unknown. They look to have been a source of hydrodynamic drag, preventing Euhoplites from swimming at high speeds. Studying them may give some insight into the lifestyle of this ancient marine predator. Euhoplites had shells ranging in size up to a few inches.
Thursday 10 January 2019
FIRE-KISSED ARTHROPOD
As his name indicates, he is from a fossil site in the Yunnan region near Kunming. He is unusual in many ways, both because of the remarkable level of preservation and the position in which he was found. This fellow was a bit of a tippy arthropod. His carapace had flipped over before fossilisation, allowing researchers to to examine this fuxianhuiid's head and legs in great detail without a carapace in the way.
The roughly 518-million-year-old site contains a dizzying abundance of beautifully preserved weird and wonderful life-forms, from jellyfish and comb jellies to arthropods and algae and is about 10 million years older than the Burgess Shale. Photo credit: Yie Jang (Yunnan University)
Wednesday 9 January 2019
Tuesday 8 January 2019
WASH ON, WASH OFF
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.
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 coloring which attracts fish from around the reefs.
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.
Monday 7 January 2019
FRATERCULA ARCTICA
They are good little swimmers as you might expect but surprisingly they are great flyers, too! Once they get some speed on board, they can fly up to 88 km an hour.
Sunday 6 January 2019
ICHTHYOSAURIA
Saturday 5 January 2019
HOLCOPHYLLOCERAS MEDITERRANEUM
Amazing suturing on this lovely ammonite and great detail, allowing us to see how he grew, adding to his size, chamber by chamber, building out his spiral shape.
Ammonite shells had many chambers divided by walls called septa. Nautiloids had simple septa with a single arc whereas ammonites developed septa with intricate folds, lobes and saddles. They also developed delicate feather-like or fern-like lacey patterns, called sutures, on the outer shell. You sometimes see them on polished or water worn specimens and in the photos of this fellow below.
The chambers were connected by a tube called a siphuncle which allowed for the control of buoyancy with the hollow inner chambers of the shell acting as air tanks to help them float. A bit like internal water wings you might use to learn how to swim as a kid.
We can see the edges of this specimen's shell where it would have continued out to the last chamber, the body-chamber, where the ammonite lived. Picture a squid or octopus, now add a shell. That's him!
Friday 4 January 2019
MEGALODON TOOTH
These big beasties lived during Oligocene to Miocene. This fellow is considered to be a close relative of the famous prehistoric mega-toothed shark, C. megalodon, although the classification of this species is still disputed.
Swiss naturalist Louis Agassiz first identified this shark as a species of Carcharodon in 1843. In 1906, Ameghino renamed this shark as C. chubutensis. In 1964, shark researcher, L. S. Glikman recognized the transition of Otodus obliquus to C. auriculatus. In 1987, shark researcher, H. Cappetta reorganized the C. auriculatus - C. megalodon lineage and placed all related mega-toothed sharks along with this species in the genus Carcharocles.
At long last, the complete Otodus obliquus to C. megalodon progression began to look clear. Since then, C. chubutensis has been re-named into Otodus chubutensis, also the other chronospecies of the Otodus obliquus - O. megalodon lineage. Chubutensis appears at the frontier Upper Oligocene to Lowest Miocene (evolving from O. angustidens which has stronger side cusps) and turns into O. megalodon in the Lower to Middle Miocene, where the side cusps are already absent. Despite previous publications, there is no chubutensis in the Pliocene.
Victor Perez and his team published on the transition between Carcharocles chubutensis and Carcharocles megalodon (Otodontidae, Chondrichthyes): lateral cusplet loss through time in March of 2018. In their work, they look at the separation between all the teeth of Carcharocles chubutensis and Carcharocles megalodon and published that it is next to impossible to divide them up as a complex mosaic evolutionary continuum characterizes this transformation, particularly in the loss of lateral cusplets.
The cuspleted and uncuspleted teeth of Carcharocles spp. are designated as chronomorphs because there is wide overlap between them both morphologically and chronologically. In the lower Miocene Beds (Shattuck Zones) 2–9 of the Calvert Formation (representing approximately 3.2 million years, 20.2–17 Ma, Burdigalian) both cuspleted and uncuspleted teeth are present, but cuspleted teeth predominate, constituting approximately 87% of the Carcharocles spp. teeth represented in their samples.
In the middle Miocene Beds 10–16A of the Calvert Formation (representing approximately 2.4 million years, 16.4–14 Ma, Langhian), there is a steady increase in the proportion of uncuspleted Carcharocles teeth.
In the upper Miocene Beds 21–24 of the St. Marys Formation (representing approximately 2.8 million years, 10.4–7.6 Ma, Tortonian), lateral cusplets are nearly absent in Carcharocles teeth from our study area, with only a single specimen bearing lateral cusplets. The dental transition between Carcharocles chubutensis and Carcharocles megalodon occurs within the Miocene Chesapeake Group. Although their study helps to elucidate the timing of lateral cusplet loss in Carcharocles locally, the rationale for this prolonged evolutionary transition remains unclear.
The specimen you see here is in the Geological Museum in Lisbon. The photo credit goes to the deeply awesome Luis Lima who shared some wonderful photos of his recent visit to their collections.
If you'd like to read the paper from Perez, you can find it here:
https://www.tandfonline.com/doi/full/10.1080/02724634.2018.1546732
Thursday 3 January 2019
ICELAND: TORFAJOKULL
Landmannalaugar is at the northern tip of the Laugavegur hiking trail that leads through natural geothermal hot springs and an austere yet poetically beautiful landscape.
Here, you can see the Northern Lights play through the darkness of a night sky without light pollution and bask in the raw geology of this rugged land.
The Fjallabak region takes its name from the numerous wild and rugged mountains with deeply incised valleys, which are found there. The topography of the Torfajokull, a central volcano found within the Fjallabak Nature Reserve, is a direct result of the region being the largest rhyolite area in Iceland and the largest geothermal area (after Grimsvotn in Vatnajokull).
The Torfajokull central volcano is an active volcanic system but is now in a declining fumarolic stage as exemplified by numerous fumaroles and hot springs. The hot pools at Landmannalaugar are but one of many manifestations of geothermal activity in the area, which also tends to alter the minerals in the rocks, causing the beautiful colour variations from red and yellow to blue and green, a good example being Brennisteinsalda. Geologists believe that the Torfajokull central volcano is a caldera, the rim being Haalda, Suðurnamur, Norður-Barmur, Torfajokull, Kaldaklofsfjoll and Ljosartungur.
The bedrock of the Fjallabak Nature Reserve dates back 8-10 million years. At that time the area was on the Reykjanes – Langjokull ridge rift zone. The volcano has been most productive during the last 2 million years, that is during the last Ice Age Interglacial rhyolite lava (Brandsgil) and sub-glacial rhyolite (erupted under ice/water, examples being Blahnukur and Brennisteinsalda are characteristic formations in the area. To the north of the Torfajokull region sub-glacial volcanic activity produced the hyaloclastites (moberg) mountains, such as Lodmundur and Mogilshofdar.
Volcanic activity in recent times (last 10.000 years) has been restricted to a few northeast – southwest fissures, the most recent one, the Veidivotn fissure from 1480, formed Laugahraun (by the hut at Landmannalaugar), Namshraun, Nordurnamshraun, Ljotipollur and other craters which extend 30 km, further to the north Eruptions in the area tend to be explosive and occur every 500 – 800 years, previous known eruptions being around A. D 150 and 900.
MEGALOSAURUS BUCKLANDII
Notable collections include the world's first described dinosaur, Megalosaurus bucklandii, and the world-famous Oxford Dodo, the only soft tissue remains of the extinct dodo. Although fossils from other areas have been assigned to the genus, the only certain remains of Megalosaurus come from Oxfordshire and date to the late Middle Jurassic. In 1824, Megalosaurus was the first genus of non-avian dinosaur to be validly named. The type species is Megalosaurus bucklandii, named in 1827.
In 1842, Megalosaurus was one of three genera on which Richard Owen based his Dinosauria. On Owen's direction, a model was made as one of the Crystal Palace Dinosaurs, which greatly increased the public interest for prehistoric reptiles. Subsequently, over fifty other species would be classified under the genus, originally because dinosaurs were not well known, but even during the 20th century after many dinosaurs had been discovered. Today it is understood these additional species were not directly related to M. bucklandii, which is the only true Megalosaurus species. Because a complete skeleton of it has never been found, much is still unclear about its build.
The Museum is as spectacular today as when it opened in 1860. As a striking example of Victorian neo-Gothic architecture, the building's style was strongly influenced by the ideas of 19th-century art critic John Ruskin. Ruskin believed that architecture should be shaped by the energies of the natural world, and thanks to his connections with a number of eminent Pre-Raphaelite artists, the Museum's design and decoration now stand as a prime example of the Pre-Raphaelite vision of science and art.
On 30 June 1860, the Museum hosted a clash of ideologies that has become known as the Great Debate. Even before the collections were fully installed, or the architectural decorations completed, the British Association for the Advancement of Science held its 30th annual meeting to mark the opening of the building, then known as the University Museum. It was at this event that Samuel Wilberforce, Bishop of Oxford, and Thomas Huxley, a biologist from London, went head-to-head in a debate about one of the most controversial ideas of the 19th century – Charles Darwin's theory of evolution by natural selection.
Wednesday 2 January 2019
ALSACE AMMONITE
The aptychus we see here, hard anatomical structures or curved shelly plates now understood to be part of the body of an ammonite or nautilus, are often referred to as beaks. If you look closely at this specimen, you can see the beak of the nautilus, that wee pointed piece, near the centre. Collection of Ange Mirabet, Strasbourg, France.
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Tuesday 1 January 2019
Monday 31 December 2018
JELLYFISH: GAGISAMA
Sea jellies and jellyfish are the common names for the medusa-phase or adult phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria — more closely related to anemones and corals.
Jellyfish are not fish at all. Jellyfish evolved millions of years before true fish.
The oldest conulariid scyphozoans — picture an ice-cream cone with fourfold symmetry — appeared between 635 and 577 million years ago in the Neoproterozoic of the Lantian Formation a 150-meter-thick sequence of rocks deposited in southern China.
Others are found in the youngest Ediacaran rocks of the Tamengo Formation of Brazil, c. 505 mya, through to the Triassic. Cubozoans and hydrozoans appeared in the Cambrian of the Marjum Formation in Utah, USA, c. 540 mya. Like other soft-bodied organisms, ctenophores (comb jellies), sea jellies and jellyfish only produce fossils only under exceptional taphonomic conditions — think rare.
I have seen all sorts of their brethren growing up on the west coast of Canada. I have seen them in tide pools, washed up on the beach and swam amongst thousands of Moon Jellyfish while scuba diving in the Salish Sea. Their movement in the water is marvellous.
In the Kwak̓wala language of the Kwakiutl or Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest, jellyfish are known as ǥaǥisama.The watercolour ǥaǥisama you see here is a bit of fancy. While I chose blue, purple and pink for these lovelies, they also come in bright yellow, orange and relatively clear — and are often luminescent.
Jellyfish such as comb jellies produce bright flashes to startle a predator, others such as siphonophores can produce a chain of light or release thousands of glowing particles into the water as a mimic of small plankton to confuse the predator.
For most jellyfish bioluminescence is used for defence against predators — and about half of all jellyfish are bioluminescent. Some produce a glowing sticky slime that clings to predators making them vulnerable to other predators. Some jellyfish can release their tentacles as glowing decoys. So you see that there are many strategies for using bioluminescence by jellyfish.
All bioluminescence comes from energy released from a chemical reaction. This is very different from other sources of light, such as from the sun or a light bulb, where the energy comes from heat. In a luminescent reaction, two types of chemicals, called luciferin and luciferase, combine together. The luciferase acts as an enzyme, allowing the luciferin to release energy as it is oxidized. The colour of the light depends on the chemical structures of the chemicals.
There are more than a dozen known chemical luminescent systems, indicating that bioluminescence evolved independently in different groups of organisms. One type of luciferin is called coelenterazine, found in jellyfish, shrimp, and fish. Dinoflagellates and krill share another class of unique luciferins, while ostracods (firefleas) and some fish have a completely different luciferin. The occurrence of identical luciferins for different types of organisms suggests a dietary source for some groups. Organisms such as bacteria and fireflies have unique luminescent chemistries. In many other groups, the chemistry is still unknown
Some of the most amazing deep-sea jellyfish are the comb jellies, which can get as large as a basketball, and are in some cases so fragile that they are almost impossible to collect intact.
Also spectacular are the siphonophores, some of which can reach several meters in length. Siphonophores deploy many tentacles like a gill net casting for small fish.