Tuesday, 31 December 2019
Crinoids are unusually beautiful and graceful members of the phylum Echinodermata. They resemble an underwater flower swaying in an ocean current. But make no mistake they are marine animals. Picture a flower with a mouth on the top surface that is surrounded by feeding arms. Awkwardly, add an anus right beside that mouth. That's him!
Crinoids with root-like anchors are called Sea Lilies. They have graceful stalks that grip the ocean floor. Those in deeper water have longish stalks up to 3.3 ft or a meter in length.
Then there are other varieties that are free-swimming with only vestigial stalks. They make up the majority of this group and are commonly known as feather stars or comatulids. Unlike the sea lilies, the feather stars can move about on tiny hook-like structures called cirri. It is this same cirri that allows crinoids to latch to surfaces on the seafloor. Like other echinoderms, crinoids have pentaradial symmetry. The aboral surface of the body is studded with plates of calcium carbonate, forming an endoskeleton similar to that in starfish and sea urchins.
These make the calyx somewhat cup-shaped, and there are few, if any, ossicles in the oral (upper) surface called a tegmen. It is divided into five ambulacral areas, including a deep groove from which the tube feet project, and five interambulacral areas between them. The anus, unusually for echinoderms, is found on the same surface as the mouth, at the edge of the tegmen.
Crinoids are alive and well today. They are also some of the oldest fossils on the planet. We have lovely fossil specimens dating back to the Ordovician.
Sunday, 29 December 2019
I'd expected to learn that the locality contained a single or just a few partial specimens, but the fossils beds are abundant with large, 45–70 cm, four-year-old adult salmon concentrated in a beautiful sequence of death assemblages.
The specimens include individuals with enlarged breeding teeth and worn caudal fins. It is likely that these salmon acted very similar to their modern counterparts with males partaking in competitive and sneaky tactics to gain access to the sexiest (large and red) females who were ready to mate. These ancient salmon had migrated, dug their nests, spawned and defended their eggs prior to their death. For now, we're referring to the species found here as Oncorhynchus nerka, as they have many of the characteristics of sockeye salmon, but also several minor traits of the Pink Salmon, Oncorhynchus gorbuscha.
Gerald Smith, a retired University of Michigan professor was shown the specimens and recognized them as Pleistocene, a time when the northern part of North America was undergoing a series of glacial advances and retreats that carved their distinctive signature into the Pacific Northwest. It looks as though this population diverged from the original species about one million years ago, possibly when the salmon were deposited at the head of a proglacial lake impounded by the Salmon Springs advancement of a great glacier known as the Puget lobe of the Cordilleran Ice Sheet. Around 17,000 years ago, this 3,000 foot-thick hunk of glacial ice had made its way down from Canada, sculpting a path south and pushing its way between the Cascade and Olympic Mountains. The ice touched down as far south as Olympia, stilled for a few hundred years, then began to melt.
After the ice began melting and retreating north, the landscape slowly changed — both the land and sea levels rising — and great freshwater lakes forming in the lowlands filled with glacial waters from the melting ice. The sea levels rose quite considerably, about one and a half centimetres per year between 18,000 and 13,000 years ago. The isostatic rebound (rising) of the land rose even higher with an elevation gain of about ten centimetres per year from 16,000 to 12,500 years ago.
Around 14,900 years ago, sea-levels had risen to a point where the salty waters of Puget Sound began to slowly fill the lowlands. Both the land and sea continued to rise and by 5,000 years ago, the sea level was about just over 3 meters lower than it is today. The years following were an interesting time in the geologic history of the Pacific Northwest. The geology of the South Fork Skokomish River continued to shift, undergoing a complicated series of glacial damming and river diversions after these salmon remains were deposited.
Today, we find their remains near the head of a former glacial lake at an elevation of 115 metres on land owned by the Green Diamond Company. The first fossil specimens were found back in 2001 by locals fishing for trout along the South Fork Skokomish River.
The fossil specimen you see here is housed in the Burke Museum collection. They opened the doors to their new building and exhibitions in the Fall of 2019. These photos are by the deeply awesome John Fam from a trip to see the newly opened exhibits this year. If you fancy a visit to the Burke Museum, check out their website here: https://www.burkemuseum.org/.
David B. Williams did up a nice piece on historylink.org on the Salmon of the Puget lowland. You can find his work here: https://www.historylink.org/File/20263
If you'd like to read more of the papers on the topic, check out:
Smith, G., Montgomery, D., Peterson, N., and Crowley, B. (2007). Spawning sockeye salmon fossils in Pleistocene lake beds of Skokomish Valley, Washington. Quaternary Research, 68(2), 227-238. doi:10.1016/j.yqres.2007.03.007.
Easterbrook, D.J., Briggs, N.D., Westgate, J.A., and Gorton, M.P. (1981). Age of the Salmon Springs Glaciation in Washington. Geology 9, 87–93.
Hikita, T. (1962). Ecological and morphological studies of the genus Oncorhynchus (Salmonidae) with particular consideration on phylogeny. Scientific Reports of the Hokkaido Salmon Hatchery 17, 1–97.
If you fancy a read of Crowley's work on Late Oligocene Mysticete from Washington State, you can check out: Crowley, B., & Barnes, L. (1996). A New Late Oligocene Mysticete from Washington State. The Paleontological Society Special Publications, 8, 90-90. doi:10.1017/S2475262200000927
Saturday, 28 December 2019
|Cadoceras tonniense, Harrison Lake, British Columbia|
These rare beauties are from the Lower Callovian, 164.7 - 161.2 million years ago. Interestingly, the ammonites from here are quite similar to the ones found within the lower part of the Chinitna Formation, Alaska and Jurassic Point, Kyuquot, on the west coast of Vancouver Island.
These species are from Callomon's (1984) Cadoceras comma Fauna B8 for the western Cordillera of North America, which is equivalent in part to the Macrocephalus Zone of Europe of the Early Callovian. The faunal association at locality 17 near Harrison suggests a more precise correlation to Callomon's zonation; namely, the Cadoceras wosnessenskii Fauna B8(e) found in the Chinitna Formation, southern Alaska (Imlay, 1953b). The type specimen is USNM 108088, from locality USGS Mesozoic 21340, Iniskin Peninsula, found in a Callovian marine siliciclastic in the Chinitna Formation of Alaska.
There are many fossils to be found on the west side of the Harrison lake near the town of Harrison, British Columbia. Exploration of the geology around Harrison Lake has a long history with geologists from the Geological Survey of Canada studying geology and paleontological exposures as far back as the 1880s. They were probably looking for coal exposures — but happy day, they found fossils!
The paleo outcrops were first mentioned in the Geological Survey of Canada's Director's Report in 1888 (Selwyn, 1888), then studied by Whiteaves a year later. Whiteaves identified the prolific bivalve Aucella (now Buchia) from several specimens collected in 1882 by A. Bowman of the Geological Survey of Canada. The first detailed geological work in the Harrison Lake area was undertaken in a doctoral study by Crickmay (1925), who compiled a geological map, describing the stratigraphy and establishing the formational names, many of which we still use today. Crickmay went on to interpret the paleogeography and structure of the region.
There was a time when Jim Haggart asked one of the VanPS members to take up the mantle and try to cherry-pick through a boatload of buchia finds to sort their nomenclature. I'm not sure if that project ever bore fruit.
Around Harrison Lake, Callovian beds of the Mysterious Creek Formation are locally overlain disconformably by 3,000 feet of Early Oxfordian conglomerate. We find Cadoceras tonniense here and at nine localities in the Alaska Peninsula and Cook Inlet regions of the USA.
If you'd like to visit the site at Chinitna Bay, you'll want to hike into 59.9° N, 153.0° W: paleo-coordinates 31.6° N, 86.6° W.
A. J. Arthur, P. L. Smith, J. W. H. Monger and H. W. Tipper. 1993. Mesozoic stratigraphy and Jurassic paleontology west of Harrison Lake, southwestern British Columbia. Geological Survey of Canada Bulletin 441:1-62
R. W. Imlay. 1953. Callovian (Jurassic) ammonites from the United States and Alaska Part 2. The Alaska Peninsula and Cook Inlet regions. United States Geological Survey Professional Paper 249-B:41-108
An overview of the tectonic history of the southern Coast Mountains, British Columbia; Monger, J W H; in, Field trips to Harrison Lake and Vancouver Island, British Columbia; Haggart, J W (ed.); Smith, P L (ed.). Canadian Paleontology Conference, Field Trip Guidebook 16, 2011 p. 1-11 (ESS Cont.# 20110248).
Wednesday, 25 December 2019
Tuesday, 24 December 2019
In the time expanse in which we live our very short human lives, the Earth's crust appears permanent. A fixed outer shell – terra firma. Aside from the rare event of an earthquake or the eruption of Mount St. Helen’s, our world seems unchanging, the landscape constant. In fact, it has been on the move for billions of years and continues to shift each day. As the earth’s core began cooling, some 4.5 billion years ago, plates, small bits of continental crust, have become larger and smaller as they are swept up in or swept under their neighbouring plates. Large chunks of the ocean floor have been uplifted, shifted and now find themselves thousands of miles in the air, part of mountain chains far from the ocean today or carved by glacial ice into valleys and basins.
Two hundred million years ago, Washington was two large islands, bits of the continent on the move westward, eventually bumping up against the North American continent and calling it home. Even with their new fixed address, the shifting continues; the more extreme movement has subsided laterally and continues vertically. The upthrusting of plates continue to move our mountain ranges skyward, the path of least resistance. This dynamic movement has created the landscape we see today and helped form the fossil record that tells much of our recent and ancient history.
Monday, 23 December 2019
The Homestake Gold Mine in Lawrence County, South Dakota was a going concern from about 1876 to 2001.
The mine produced more than forty million troy ounces of gold in its one hundred and twenty-five-year history, dating back to the beginnings of the Black Hills Gold Rush. To give its humble beginnings a bit of context, Homestake was started in the days of miners hauling loads of ore via horse and mule and the battles of the Great Sioux War. Folk moved about via horse-drawn buggies and Alexander Graham Bell had just made his first successful telephone call. Wyatt Earp was working in Dodge City, Kansas (he had yet to get the heck outta Dodge) and Mark Twain was in the throes of publishing “The Adventures of Tom Sawyer.” — Ooh, and Thomas Edison had just opened his first industrial research lab in Menlo Park.
The mine is part of the Homestake Formation, an Early Proterozoic layer of iron carbonate and iron silicate that produces auriferous greenschist gold. What does all that geeky goodness mean? If you were a gold miner it would be music to your ears. They ground down that schist to get the glorious good stuff and made a tiny wee sum doing so. But then gold prices levelled off — from 1997 ($287.05) to 2001 ($276.50) — and rumblings from the owners started to grow. They bailed in 2001, ironically just before gold prices started up again.
But back to 2001, that levelling saw the owners look to a new source of revenue in an unusual place. One they had explored way back in the 1960s in a purpose-built underground laboratory that sounds more like something out of a science fiction book. The brainchild of chemist and astrophysicists, John Bahcall and Raymond Davis Jr. from the Brookhaven National Laboratory in Upton, New York, the laboratory was used to observe solar neutrinos, electron neutrinos produced by the Sun as a product of nuclear fusion.
Davis had the ingenious idea to use 100,000 gallons of dry-cleaning solvent, tetrachloroethylene, with the notion that neutrinos headed to Earth from the Sun would pass through most matter but on very rare occasions would hit a chlorine-37 atom head-on turning it to argon-37. His experiment was a general success, detecting electron neutrinos, though his technique failed to sense two-thirds of the number predicted. In particle physics, neutrinos come in three types: electron, muon and tau. Think yellow, green, blue. What Davis had failed to initially predict was the neutrino oscillation en route to Earth that altered one form of neutrino into another. Blue becomes green, yellow becomes blue... He did eventually correct this wee error and was awarded the Nobel Prize in Physics in 2002 for his efforts.
Though Davis’ experiments were working, miners at Homestake continued to dig deep for ore in the belly of the Black Hills of western South Dakota for almost another forty years. As gold prices levelled out and ore quality dropped the idea began to float to repurpose the mine as a potential site for a new Deep Underground Engineering Laboratory (DUSEL).
A pitch was made and the National Science Foundation awarded the contract to Homestake in 2007. The mine is now home to the Deep Underground Neutrino Experiment (DUNE) using DUSEL and Large Underground Xenon to look at both neutrinos and dark particle matter. It is a wonderful re-purposing of the site and one that few could ever have predicted. Well done, Homestake. The future of the site is a gracious homage to the now deceased Davis. He would likely be delighted to know that his work continues at Homestake and our exploration of the Universe with it.
Saturday, 21 December 2019
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.
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.
Friday, 20 December 2019
Over the past 170 years, the Late Devonian Miguasha biota from eastern Canada has yielded a diverse aquatic assemblage including 20 species of lower vertebrates (anaspids, osteostra-cans, placoderms, acanthodians, actinopterygians and sarcopterygians), a more limited invertebrate assemblage, and a continental component including plants, scorpions and millipedes.
Originally interpreted as a freshwater lacustrine environment, recent paleontological, taphonomic, sedimentological and geochemical evidence corroborates a brackish estuarine setting. Over 18,000 fish specimens have been recovered showing various modes of fossilization, including uncompressed material and soft-tissue preservation. Most vertebrates are known from numerous, complete, articulated specimens. Exceptionally well-preserved larval and juvenile specimens have been identified for 14 out of the 20 species of fishes, allowing growth studies. Numerous horizons within the Escuminac Formation are now interpreted as either Konservat– or Konzentrat–Lagerstätten.
This replica was purchased at the Musée d'Histoire Naturelle, Miguasha (MHNM) and is in the collection of the deeply awesome (and well-travelled) John Fam.
Great Canadian Lagerstätten 4. The Devonian Miguasha Biota (Québec): UNESCO World Heritage Site and a Time Capsule in the Early History of Vertebrates, Richard Cloutier, Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, 300 allée des Ursulines, Rimouski, QC, Canada, G5L 3A1, firstname.lastname@example.org, http://dx.doi.org/10.12789/geocanj.2013.40.008
Thursday, 19 December 2019
Strictly speaking, Sarcosuchus was not a crocodile as we know them today, but a kind of pre-crocodile. These early croc-types were Crocodylomorphs.
This crocodylian lineage (clade Pseudosuchia, formerly Crurotarsi) was a very diverse and adaptive group of reptiles. We used to lump all known living and extinct crocodiles indiscriminately into the order Crocodilia. Sometime in the late 1980s, we finally moved all living species into the order Crocodilia, segregating closely related extinct relatives such as Mekosuchus. Our true "modern" crocodiles, now all safely ensconced in the order Crocodilia without their ancient ancestors, arrived millions of years after the first crocodylomorphs, with the first members of the modern species arriving on the scene in the Upper Cretaceous.
The Crocodylomorpha were a very ancient group of animals, at least as old as the dinosaurs, who evolved into a very diverse spectrum of weird and wonderful forms you might not recognize as croc-like. During the Jurassic and the Cretaceous, marine Crocodylomorphs in the family Metriorhynchidae, such as Metriorhynchus, evolved forelimbs that were paddle-like and had a tail similar to modern fish. Dakosaurus andiniensis, a species closely related to Metriorhynchus, had a skull that was adapted to feast upon large marine reptiles. We see several (unexpected) herbivorous terrestrial species during the Cretaceous, such as the tiny and adorable Simosuchus clarki and Chimaerasuchus paradoxus, both roughly the size of a dog. During the Cenozoic, a number of lineages left their ancient river homes and became wholly terrestrial predators.
Sarcosuchus was one of the largest early crocodile-like reptiles, reaching up to 9.5 m in body length and weighing up to 8 to 10 tons. He was almost twice as long as our modern saltwater crocodiles, so one big croc! These big beasts lived and hunted in ancient rivers, grabbing and crushing prey that came too close to the water.
The first remains were discovered during field expeditions in the Sahara led by French paleontologist, Albert-Félix de Lapparent, from 1946 to 1959. Remains were found of skull fragments, vertebrae, teeth, and scutes.
In 1964, an almost complete skull was found in Niger by the French CEA, but it was not until 1997 and 2000 that most of its anatomy became known to science when an expedition led by the American paleontologist Paul Sereno discovered six new specimens, including one with about half the skeleton intact and most of the spine.
A common method to estimate the size of crocodiles and crocodile-like reptiles is the use of the length of the skull measured in the midline from the tip of the snout to the back of the skull table since in living crocodilians there is a strong correlation between skull length and total body length in subadult and adult individuals irrespective of their sex, this method was used by Sereno et al. (2001) for Sarcosuchus due to the absence of a complete enough skeleton. Two regression equations were used to estimate the size of S. imperator, they were created based on measurements gathered from 17 captive gharial individuals from northern India and from 28 wild saltwater crocodile individuals from northern Australia, both datasets supplemented by available measurements of individuals over 1.5 m (4.92 ft) in length found in the literature.
The largest known skull of Sarcosuchus imperator (the type specimen) is 1.6 m (5.25 ft) long (1.5 m (4.92 ft) in the midline), and it was estimated that the individual it belonged to had a total body length of 11.65 m (38.2 ft), its snout-vent length of 5.7 m (18.7 ft) was estimated using linear equations for the saltwater crocodile and in turn, this measurement was used to estimate its body weight at 8 tonnes (8.8 short tons). These new measurements meant Sarcosuchus was able to reach a maximum body size not only greater than previously estimated but also greater than that of the Miocene "Beak crocodile" Rhamphosuchus, the Late Cretaceous Deinosuchus crocodilian related to our modern alligators, and the Miocene Purussaurus.
However, extrapolation from the femur of a subadult individual as well as measurements of the skull width further showed that the largest S. imperator was significantly smaller than was estimated by Sereno et al. (2001) based on modern crocodilians. O’Brien et al. (2019) estimated the length of the largest S. imperator specimen at 9.5 meters and body weight at 4.7 tons based on longirostrine crocodylians skull width to total length ratio. This estimate is very close to the femur based estimate is 9.1 m (29.9 ft).
Sereno, Paul C.; Larson, Hans C. E.; Sidor, Christian A.; Gado, Boubé (2001). "The Giant Crocodyliform Sarcosuchus from the Cretaceous of Africa". Science. 294 (5546): 1516–9. Bibcode:2001Sci...294.1516S. doi:10.1126/science.1066521. PMID 11679634.
Wednesday, 18 December 2019
The end-Ordovician extinctions had a profound effect on shallow-water benthic communities, including the Crinoidea. A hard-won recovery after the extinctions led (not surprisingly) to macroevolutionary turnover in crinoid faunas. We do not have many of these exposures to study this impactful moment in our evolutionary history and our opportunity to see this transition in Canada is special indeed. Anticosti Island is the most complete Ordovician-Silurian boundary section recording shallow-water habitats.
Both new taxa and changes in Anticosti Island stratigraphic nomenclature are addressed in the paper. New taxa include Becsciecrinus groulxi n. sp., Bucucrinus isotaloi n. sp., Jovacrinus clarki n. sp., Plicodendrocrinus petryki n. sp., Plicodendrocrinus martini n. sp., Thalamocrinus daoustae n. sp., and Lateranicrinus saintlaurenti n. gen. n. sp.
The status of Xenocrinus rubus as a boundary-crossing taxon is confirmed, range extensions of several taxa are documented, and the distribution of crinoids with the revised stratigraphic nomenclature is documented. This publication is a labour of love covering many years of a collaborative effort by Cournoyer and William Ausich. Definitely give it a read:
Tuesday, 17 December 2019
Since ancient times, Volterra, a key trading center and one of the most important Etruscan towns has been known as the city of alabaster.
The Etruscans mined alabaster in the nearby hills and considered it the stone of the dead. The mineral was used for elaborate funerary urns and caskets that housed the ashes of the departed, prized for its durability, beautiful coloration, natural veining and translucence. When the Romans ascended, alabaster fell out of favour and marble became the preferred sculpting material.
To work alabaster requires an assortment of hand tools, an artistic eye, and a tolerance for vast clouds of dust. An alabastraio begins with a block or chunk of alabaster. If the final product is to be a vase or bowl, the stone is turned on a lathe similar to what is used to make pottery and then shaped with chiselling tools.
Although alabaster and marble may seem similar in appearance when polished, they are very different materials, particularly when it comes to their hardness and mineral content. Alabaster is a fine-grained form of gypsum, a sedimentary rock made from tiny crystals visible only under magnification. The ancient Egyptians preferred alabaster for making their sphinxes or creating burial objects such as cosmetic jars. The purest alabaster is white and a bit translucent; impurities such as iron oxide cause the spidery veins. I like a mix of both, preferably backlit to show the blending of colour.
I had the very great pleasure of travelling to Carrara with Guylaine Rondeau many years ago, making her stop at every single roadcut along the way. More on those wonders later...
Alabaster is the common name applied to a few types of rocks. Translucent and beautiful, alabaster generally includes some calcium in gypsum. Gypsum is a composite of calcium sulphate, a type of sedimentary rock formed millions of years ago in the depths of a shallow sea. Left by time and tide, it evaporated into the creamy (full of lovely chemical impurities) or fully transparent (pure gypsum) stone we see today.
Alabaster is simply beautiful. In the right hands, it can be sculpted to evoke the most wondrous reflections of light and emotion. And it stands the test of time, becoming more beautiful with each passing year... rather like my Auntie Gail. I'm thinking of you as I write this my beautiful one. Happy 70th birthday to my Auntie of Alabaster. xo
Monday, 16 December 2019
This specimen shows a pathology, a slight deviation to the side of the siphonal of the ammonite. We see Prolyelliceras from the Albian to Middle Albian from five localities in Peru.
Reference: M. M. Knechtel. 1947. Cephalopoda. In: Mesozoic fossils of the Peruvian Andes, Johns Hopkins University Studies in Geology 15:81-139
W. J. Kennedy and H. C. Klinger. 2008. Cretaceous faunas from Zululand and Natal, South Africa. The ammonite subfamily Lyelliceratinae Spath, 1921. African Natural History 4:57-111. The beauty you see here is in the collection of José Juárez Ruiz
Sunday, 15 December 2019
The Iberian Peninsula is the westernmost of the three major southern European peninsulas — the Iberian, Italian, and Balkan. It is bordered on the southeast and east by the Mediterranean Sea, and on the north, west, and southwest by the Atlantic Ocean. The Pyrenees mountains are situated along the northeast edge of the peninsula, where it adjoins the rest of Europe. Its southern tip is very close to the northwest coast of Africa, separated from it by the Strait of Gibraltar and the Mediterranean Sea.
The Iberian Peninsula contains rocks of every geological period from the Ediacaran to the recent, and almost every kind of rock is represented. To date, there are 127 localities of theropod fossil finds ranging from the Callovian-Oxfordian (Middle-Upper Jurassic) to the Maastrichtian (Upper Cretaceous), with most of the localities concentrated in the Kimmeridgian-Tithonian interval and the Barremian and Campanian stages. The stratigraphic distribution is interesting and suggests the existence of ecological and/or taphonomic biases and palaeogeographical events that warrant additional time and attention.
As well as theropods, we also find their plant-eating brethren. This was the part of the world where the last of the hadrosaurs, the 'duck-billed' dinosaurs, lived then disappeared in the Latest Cretaceous K/T extinction event, 65.5 million years ago.
The core of the Iberian Peninsula consists of a Hercynian cratonic block known as the Iberian Massif. On the northeast, this is bounded by the Pyrenean fold belt, and on the southeast, it is bounded by the Baetic System. These twofold chains are part of the Alpine belt. To the west, the peninsula is delimited by the continental boundary formed by the magma-poor opening of the Atlantic Ocean. The Hercynian Foldbelt is mostly buried by Mesozoic and Tertiary cover rocks to the east but nevertheless outcrops through the Sistema Ibérico and the Catalan Mediterranean System. The photo you see here is care of the awesome Pedro Marrecas from Lisbon, Portugal. Hola, Pista de baile jurásica!
Pereda-Suberbiola, Xabier; Canudo, José Ignacio; Company, Julio; Cruzado-Caballero, Penélope; Ruiz-Omenaca, José Ignacio. "Hadrosauroid dinosaurs from the latest Cretaceous of the Iberian Peninsula" Journal of Vertebrate Paleontology 29(3): 946-951, 12 de septiembre de 2009.
Pereda-Suberbiola, Xabier; Canudo, José Ignacio; Cruzado-Caballero, Penélope; Barco, José Luis; López-Martínez, Nieves; Oms, Oriol; Ruíz-Omenaca, José Ignacio. Comptes Rendus Palevol 8(6): 559-572 septiembre de 2009.
Saturday, 14 December 2019
With fossil bone, you will be able to see the different canals and webbed structure of the bone, sure signs that the object was of biological origin.
As my good friend Mike Boyd notes, without going into the distinction between dermal bone and endochondral bone (which relates to how they form - or ossify), it's worth noting that bones such as the one illustrated here will usually have a layer of smooth (or periosteal) bone on the outer surface and spongy (or trabecular) bone inside.
The distinction can be well seen in the photograph. The partial weathering away of the smooth external bone has resulted in the exposure of the spongy bone interiors. Geographic context is important, so knowing where it was found is very helpful for an ID. Knowing the geologic context of your find can help you to figure out if you've perhaps found a terrestrial or marine fossil. Did you find any other fossils nearby? Can you see pieces of fossil shells or remnants of fossil leaves? Things get tricky with erratics. That's when something has deposited a rock or fossil far from the place it originated. We see this with glaciers. The ice can act like a plow, lifting up and pushing a rock to a new location, then melting away to leave something out of context.
Friday, 13 December 2019
I know, right? It sounds much less exciting, but the process by which algae and other plant life soak up the Sun's energy, store it for millions of years, then give it all up for us to burn as fuel is a pretty fantastic tale!
Fossil fuel is a fuel formed by a natural process, the anaerobic decomposition of buried dead organisms who soaked up and stored energy from ancient photosynthesis. Picture ancient trees, algae and peat soaking up the sun, then storing that energy for us to use millions of years later. These organisms and their resulting fossil fuels are millions of years old, sometimes more than 650 million years. That's way back in the day when Earth's inhabitants were mostly viruses, bacteria and some early multi-cellular jelly-like critters.
Fossil fuels consist mainly of dead plants – coal from trees, and natural gas and oil from algae, a diverse group of aquatic photosynthetic eukaryotic organisms I like to think of as pond scum. These deposits are called fossil fuels because, like fossils, they are the remains of plants and animals that lived long ago.
If we could go back far enough, we'd find that our oil, gas, and coal deposits are really remnants of algal pools, peat bogs and ancient muddy swamps. Dead plants and algae accumulate and over time, then pressure turns the mud and dead plants into rock. Geologists call the once-living matter in the rock kerogen. If they haven't been cooked too badly, we call them fossils.
Kerogen is the solid, insoluble organic matter in sedimentary rocks and it is made from a mixture of ancient organic matter. A bit of this tree and that algae all mixed together to form a black, sticky, oily rock. The Earth’s internal heat cooks the kerogen. The hotter it gets, the faster it becomes oil, gas, or coal. If the heat continues after the oil is formed, all the oil turns to gas. The oil and gas then seep through cracks in the rocks. Much of it is lost. We find oil and gas today because some happened to become trapped in porous, sponge-like rock layers capped by non-porous rocks. We tap into these the way you might crack into a bottle of olive oil sealed with wax.
Fossil fuel experts call this arrangement a reservoir and places like Alberta, Iran and Qatar are full of them. A petroleum reservoir or oil and gas reservoir is a subsurface pool of hydrocarbons contained in porous or fractured rock formations. Petroleum reservoirs are broadly classified as conventional and unconventional reservoirs. In the case of conventional reservoirs, the naturally occurring hydrocarbons, such as crude oil or natural gas, are trapped by overlying rock formations with lower permeability. In unconventional reservoirs, the rocks have high porosity and low permeability which keeps the hydrocarbons trapped in place, so these unconventional reservoirs don't need a rock cap.
Coal is an important form of fossil fuel. Much of the early geologic mapping of Canada (and other countries) was done for the sole purpose of mapping the coal seams. You can use it to heat your home, run a coal engine or sell it for cold hard cash. It's a dirty fuel, but for a very long time, most of our industries used it as the sole means of energy. But what is so bad about burning coal and other fossil fuels? Well, many things...
Dirty or no, coal is still pretty cool. It is wild to think that a lump of coal has the same number of atoms in it as the algae or rainforest that formed it. Yep, all the same atoms, just heated and pressurized over time. When you burn a lump of coal, the same number of atoms are released when those atoms dissipate as particles of soot. You may wonder what makes a rock burn. It's not intuitive that it would be possible, and yet there it is. Coal is combustible, meaning it is able to catch fire and burn. Coal is made up mostly from carbon with some hydrogen, sulphur (smells like rotting eggs, stinky pew), oxygen and nitrogen thrown in.
It is just that the long-ago rainforest was far less dense than the coal you hold in your hand today, and so is the soot into which it dissipates once burned. The energy was captured by the algal pool or rainforest by way of photosynthesis, then that same energy is released when the coal is burnt. So the energy captured in gravity and released billions of years later when the intrinsic gravity of the coal is dissipated by burning. It's enough to bend your brain.
The Sun loses mass all the time because of its process of fusion of atomic content and radiating that energy as light. Our ancient rainforests and algal pools on Earth captured some of it. So maybe our energy transformations between the Earth and the Sun could be seen more like ping-pong matches, with energy, as the ball, passing back and forth.
As mass sucks light in (hello, photosynthesis), it becomes denser, and as mass radiates light out (hello, heat from coal), it becomes less dense. Ying, yang and the beat goes on.
Thursday, 12 December 2019
Well, Melaina, the Earth’s mass does decrease when fossil fuels are burnt. But not in the sense you were probably imagining, and only to a very, very small degree.
There is no decrease in chemical mass. Burning fossil fuels rearranges atoms into different molecules, in the process releasing energy from chemical bonds, but in the end, the same particles — protons, neutrons, and electrons — remain, so there is no decrease in mass there.
But energy is released, and some of that energy is radiated out into space, escaping from the Earth entirely. Einstein's Theory of Relativity tells us that energy does have mass: E=mc^2, or m=E/c^2. When a chemical bond that stores energy is formed, the resulting molecule has a very tiny bit more mass than the sum of the masses of the atoms from which it was formed, so a net gain. Wait, what?
Again, this is an exceedingly tiny bit. In very rough numbers, worldwide energy consumption is about 160,000 terawatt-hours per year, and about 80% of that comes from fossil fuels. That is about 450,000,000 TJ/year (tera-joules/year). The speed of light is 300,000,000 meter/s; dividing 450,000,000 TJ by (300,000,000 m/s)^2 gives a decrease in mass of 5000 kilograms per year.
That is an exceedingly small fraction — 50 billionths of one percent — of the approximately 10,000,000,000,000 kilograms of fossil fuels consumed per year. And as far as making the Earth lighter, it’s a tenth of a billionth of a billionth of a percent of the Earth’s mass.
Of course, the energy in fossil fuels originally came from the Sun, and in absorbing that sunlight the Earth’s mass increases slightly. I picture the Earth expanding and contracting, taking a deep breath, then exhaling. We don't see this when we look, but it is a great visual for imaging this never-ending give and take process. I'm not sure how we'd measure the small changes to the Earth's net mass on any given day. The mass of the Earth may be determined using Newton's law of gravitation. It is given as the force (F), which is equal to the Gravitational constant multiplied by the mass of the planet and the mass of the object, divided by the square of the radius of the planet.
Newton's insight on the inverse-square property of gravitational force was from an intuition about the motion of the earth and the moon. The mathematical formula for gravitational force is F=GMmr2 F = G Mm r 2 where G is the gravitational constant. I know, Newton’s law could use some curb appeal but it is super useful when understanding what keeps the Earth and other planets in our solar system in orbit around the Sun and why the Moon orbits the Earth. We have Newton to thank for his formulas on the gravitational potential of water when we build hydroelectricity dams. Newton’s ideas work in most but not all scenarios. When things get very, very small, or cosmic, gravity gets weird... and we head on back to Einstein to make sense of it all.
There was a very cool paper published yesterday by King Yan Fong et al. in the journal Nature that looked at heat transferring in a previously unknown way — heat transferred across a vacuum by phonons — tiny, atomic vibrations. The effect joins conduction, convection and radiation as ways for heating to occur — but only across tiny distances. The heat is transferred by phonons — the energy-carrying particles of acoustic waves, taking advantage of the Casimir effect, in which the quantum fluctuations in the space between two objects that are really, really close together result in physical effects not predicted by classical physics. This is another excellent example of the universe not playing by conventional rules when things get small. Weird, but very cool!
But the question was specifically about the mass of the Earth and the burning of fossil fuels, and that process does decrease the mass.
So it is mostly true that the Earth’s mass does not decrease due to fossil fuel burning because the numbers are so low, but not entirely true. The fuel combines with oxygen from the atmosphere to produce carbon dioxide, water vapour, and soot or ash. The carbon dioxide and water vapour go back into the atmosphere along with some of the soot or ash, the rest of which is left as a solid residue. The weight of the carbon dioxide plus the water vapour and soot is exactly the same as the weight of the original fuel plus the weight of the oxygen consumed. In general, the products of any chemical reaction whatsoever weigh the same as the reactants.
There is only one known mechanism by which Earth’s mass decreases to any significant degree: molecules of gas in the upper atmosphere (primarily hydrogen and helium, because they are the lightest) escape from Earth’s gravity at a steady rate due to thermal energy. This is counterbalanced by a steady rain of meteors hitting Earth from outer space (if you ever want to hunt them, fly a helicopter over the frozen arctic, they really stand out), containing mostly rock, water, and nickel-iron. These two processes are happening all the time and will continue at a steady rate unchanged by anything we humans do. So, the net/net is about the same.
So, the answer is that the Earth's mass is variable, subject to both gain and loss due to the accretion of in-falling material (micrometeorites and cosmic dust), and the loss of hydrogen and helium gas, respectively. But, drumroll please, the end result is a net loss of material, roughly 5.5×107 kg (5.4×104 long tons) per year.
The burning of fossil fuels has an impact on that equation, albeit a very small one, but an excellent question to ponder. A thank you and respectful nod to Les Niles and Michael McClennen for their insights and help with the energy consumption figures.
Wednesday, 11 December 2019
|Calymene blumenbachii, Theresa Paul Spink Dunn|
Calymene blumenbachii, sometimes erroneously spelled blumenbachi, is a species of trilobite found in the limestone quarries of the Wren's Nest in Dudley, England.
Nicknamed the Dudley Bug or Dudley Locust by an 18th-century quarryman, it became a symbol of the town and featured on the Dudley County Borough Council coat-of-arms. Calymene blumenbachii is commonly found in Silurian rocks (422.5-427.5 million years ago) and is thought to have lived in the shallow waters of the Silurian, in 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, and the rock here is dark grey as opposed to yellowish or whitish as it appears on other parts of the Edge, just a few miles away, in Church Stretton and elsewhere. This suggests local changes in the environment in which the rock was deposited. The Wenlock Edge quarry is closed now to further collecting but may be open to future research projects. We shall have to see.
Monday, 9 December 2019
The genus Douvilleiceras range from Middle to Late Cretaceous and can be found in Asia, Africa, Europe and North and South America. We have beautiful examples in the early to mid-Albian from the archipelago of Haida Gwaii in British Columbia. Joseph F. Whiteaves was the first to recognize the genus from Haida Gwaii when he was looking over the early collections of James Richardson and George Dawson. The beauties you see here measure 6cm to 10cm.
Sunday, 8 December 2019
Saturday, 7 December 2019
At a glance, sea stars and brittle stars look quite similar. These echinoderms generally have five radiating arms (or a multiple thereof) and creep along on the seafloor using their arms for locomotion. And they come in wonderful colours.
Sea stars and brittle stars look similar and are related but are actually quite different.
Both sea stars and brittle stars are in the phylum Echinodermata, which also includes sea cucumbers, sea urchins, sand dollars and sea lilies. The most common brittle star is the long-armed brittle star, Amphipholis squamata, a gray-blue, luminescent (glowing) species.
Echinoderms can be found making a living in our oceans and are known for their five-point radial symmetry and unique water vascular system. They typically have a tough, spiny surface, which inspired their name. In Greek, echinos means “spiny” and derma means “skin.”
A neat little evolutionary feature of these lovelies is their ability to regrow lost body parts, and sea stars and brittle stars can regrow arms if broken off or eaten.
To tell the two apart, first, look at their bodies. The modern brittle star you see to the right looks delicate, almost spindly. The sea stars you see below are more robust. Their fundamental structure is different, especially when you look at where the arms connect to the center of the body. Brittle stars have tube feet along their arms that sense light and scent.
Sea stars have thicker, triangular-shaped arms that are typically their widest at the point of connection to the center of the body. They can be found in blue, red, orange, purple, pink, white and a mixture of those same colours.
Brittle stars, on the other hand, have much thinner, more delicate arms that appear more snake-like. Their arms connect to a central disk but do not touch one another.
Although brittle stars also have a water vascular system, they twist and bend their long arms to move, instead. This means that they can move much more quickly than sea stars, especially when trying to escape a predator. Handy that!
Friday, 6 December 2019
|Pseudothurmannia picteti, Photo: Manuel Peña Nieto|
These fast-moving nektonic carnivores lived in the Cretaceous period, from the Hauterivian to the Barremian.
Shells of Pseudothurmannia can reach a diameter of about 4–12 centimetres (1.6–4.7 in). They show flat or slightly convex sides, a surface with dense ribs and a subquadrate whorl section.
We find fossils of Pseudothurmannia in Cretaceous outcrops in Antarctica, Czechoslovakia, France, Hungary, Italy, Japan, Morocco, Spain, Russia and the United States. The specimen you see here is in the collection of Manuel Peña Nieto from Córdoba, Spain and is from the Lower Cretaceous of Mallorca.
Wednesday, 4 December 2019
Tuesday, 3 December 2019
This fellow was quite the beast. The complete crocodile would have been 8-9 meters in length. Crocodiles are reptiles, which means that they are cold-blooded, are covered in dry, scaly skin, and have a backbone. They are sometimes called ‘living fossils’ because they have been living on Earth since the time of the dinosaurs.
Monday, 2 December 2019
Sunday, 1 December 2019
Porpoceras (Buchman, 1911) is a genus of ammonite that lived during the early and middle Toarcian stage of the Early Jurassic. We see members of this genus from the uppermost part of Serpentinum Zone to Variabilis Subzone. These beauties are found in Europe, Asia, North America and South America.
Ammonites belonging to this genus have evolute shells, with compressed to depressed whorl section. Flanks were slightly convex and venter has been low. The whorl section is sub-rectangular. The rib is pronounced and somewhat fibulate on inner whorls (just wee nodes here) and tuberculate to spined on the ventrolateral shoulder. It differs from Peronoceras by not having a compressed whorl section and regular nodes or fibulation. Catacoeloceras is also similar, but it has regular ventrolateral tubercules and is missing the classic nodes or fibulation of his cousins.
This specimen hails from southern France near the Rhône, one of the major rivers of Europe. It has twice the average water level of the Loire and is fed by the Rhône Glacier in the Swiss Alps at the far eastern end of the Swiss canton of Valais then passes through Lake Geneva before running through southeastern France. This 10 cm specimen was prepared by the supremely talented José Juárez Ruiz