Tuesday, 23 June 2020
NAPPING KOALA
Monday, 22 June 2020
POKEY TACHYCLOSSIDAE
Echidnas are sometimes called spiny anteaters and belong in the family Tachyglossidae (Gill, 1872). They are monotremes, an order of egg-laying mammals.
There are four species of echidnas living today. They, along with the platypus, are the only living mammals who lay eggs and the only surviving members of the order Monotremata.
Superficially, they resemble the anteaters of South America and other spiny mammals like porcupines and adorable hedgehogs. They are usually a mix of brown, black and cream in colour. While rare, there have been several reported cases of albino echidnas, their eyes pink and their spines white. Echidnas have long, slender snouts that act as both nose and mouth for these cuties. The Giant Echidna we see in the fossil record had beaks more than double this size.
Like the platypus, they are equipped with electro sensors, but while the platypus has 40,000 electroreceptors on its bill, the long-beaked echidna has only 2,000. The short-beaked echidna, which lives in a drier environment, has no more than 400 at the tip of its snout.
Echidnas evolved between 20 and 50 million years ago, descending from a platypus-like monotreme. Their ancestors were aquatic, but echidnas have adapted to life on land. Today, they weigh in at about 7 kg today but back in the Pleistocene, they were much larger. The Giant Echnida, Megalibwilia ramsayi was about 10% larger at 10 kg and Zaglossus hacketti was a whopping 30 kg.
Fossil remains are relatively rare and sadly, incomplete, but they tell us potentially two other species of Echidna thriving in the Pleistocene. We also find Robust Echidna, Zaglossus robustus, in slightly older Miocene aged outcrops in a goldmine in Australia. The Giant Echnida's we find in the fossil record are relatives of the Long-Beaked Echidnas who live in New Guinea today.
Sunday, 21 June 2020
INUKSUK: STONE SENTINELS
These rocky sentinels stand as helpful reference markers for navigation.
Translated from Inuktitut, the word inuksuk means that which acts in the capacity of a human, combining inuk or person and suk, to substitute.
Saturday, 20 June 2020
KEUPPIA: UNCOVERING OCTOBRACHIA
Wednesday, 17 June 2020
FOSSIL PEARLS
A simple search will show you a vast array of pearls being used for their ornamental value in cultures from all over the world. I suppose the best answer to why they are appealing is just that they are.
If you make your way to Paris, France and happen to visit the Louvre's Persian Gallery, do take a boo at one of the oldest pearl necklaces in existence — the Susa necklace. It hails from a 2,400-year-old tomb of long lost Syrian Queen. It is a showy piece with three rows of 72 pearls per strand strung upon a bronze wire.
A queen who truly knew how to accessorize.
I imagine her putting the final touches of her outfit together, donning the pearls and making an entrance to wow the elite of ancient Damascus. The workmanship is superb, intermixing pure gold to offset the lustre of the pearls. It is precious and ancient, crafted one to two hundred years before Christ. Perhaps a gift from an Egyptian Pharaoh or from one of the Sumerians, Eblaites, Akkadians, Assyrians, Hittites, Hurrians, Mitanni, Amorites or Babylonian dignitaries who sued for peace but brought war instead.
Questions, good questions, but questions without answers. So, what can we say of pearls? We do know what they are and it is not glamorous. Pearls form in shelled molluscs when a wee bit of sand or some other irritant gets trapped inside the shell, injuring the flesh. As a defensive and self-healing tactic, the mollusc wraps it in layer upon layer of mother-of-pearl — that glorious shiny nacre that forms pearls.
They come in all shapes and sizes from minute to a massive 32 kilograms or 70 pounds. While a wide variety of our mollusc friends respond to injury or irritation by coating the offending intruder with nacre, there are only a few who make the truly gem-y pearls. These are the marine pearl oysters, Pteriidae and a few freshwater mussels. Aside from Pteriidae and freshwater mussels, we sometimes find less gem-y pearls inside conchs, scallops, clams, abalone, giant clams and large marine gastropods.
Pearls are made up mostly of the carbonate mineral aragonite, a polymorphous mineral — same chemical formula but different crystal structure — to calcite and vaterite, sometimes called mu-calcium carbonate. These polymorphous carbonates are a bit like Mexican food where it is the same ingredients mixed in different ways. Visually, they are easy to tell apart — vaterite has a hexagonal crystal system, calcite is trigonal and aragonite is orthorhombic.
As pearls fossilize, the aragonite usually gets replaced by calcite, though sometimes by vaterite or another mineral. When we are very lucky, that aragonite is preserved with its nacreous lustre — that shimmery mother-of-pearl we know and love.
Molluscs have likely been making pearls since they first evolved 530 million years ago. The oldest known fossil pearls found to date, however, are 230-210 million years old.
This was the time when our world's landmass was concentrated into the C-shaped supercontinent of Pangaea and the first dinosaurs were calling it home. In the giant ancient ocean of Panthalassa, ecosystems were recovering from the high carbon dioxide levels that fueled the Permian extinction. Death begets life. With 95% of marine life wiped out, new species evolved to fill each niche.
While this is where we found the oldest pearl on record, I suspect we will one day find one much older and hopefully with its lovely great-great grandmother-of-pearl intact.
Monday, 15 June 2020
IS THAT YOU, MAMMA?
When this little fellow grows up, he'll dine on fish, birds (including his penguin pals), squid and krill. Krill are small crustaceans of the order Euphausiacea that look like tiny shrimp. They look similar and are both crustaceans but shrimp hail from the suborder Natantia, order Decapoda and their hearts are located in their heads. I know, right?
Sunday, 14 June 2020
PUFFIN ENJOYING A SNICK
These are pelagic seabirds that feed primarily by diving in the water. They breed in large colonies on coastal cliffs or offshore islands, nesting in crevices among rocks or in burrows in the soil. Two species, the tufted puffin and horned puffin are found in the North Pacific Ocean, while the Atlantic puffin is found in the North Atlantic Ocean. This lovely fellow, with his distinctive colouring, is an Atlantic Puffin or "Sea Parrot" from Skomer Island near Pembrokeshire in the southwest of Wales. Wales is bordered by Camarthenshire to the east and Ceredigion to the northeast with the sea bordering everything else. It is a fine place to do some birding if it's seabirds you're after.
These Atlantic Puffins are one of the most famous of all the seabirds and form the largest colony in Southern Britain. They live about 25 years making a living in our cold seas dining on herring, hake and sand eels.
The oldest alcid fossil is Hydrotherikornis from Oregon dating to the Late Eocene while fossils of Aethia and Uria go back to the Late Miocene. Molecular clocks have been used to suggest an origin in the Pacific in the Paleocene. Fossils from North Carolina were originally thought to have been of two Fratercula species but were later reassigned to one Fratercula, the tufted puffin, and a Cerorhinca species. Another extinct species, Dow's puffin, Fratercula dowi, was found on the Channel Islands of California until the Late Pleistocene or early Holocene.
The Fraterculini are thought to have originated in the Pacific primarily because of their greater diversity there; there is only one extant species in the Atlantic, compared to two in the Pacific. The Fraterculini fossil record in the Pacific extends at least as far back as the middle Miocene, with three fossil species of Cerorhinca, and material tentatively referred to that genus, in the middle Miocene to late Pliocene of southern California and northern Mexico.
Although there no records from the Miocene in the Atlantic, a re-examination of the North Carolina material indicated that the diversity of puffins in the early Pliocene was as great in the Atlantic as it is in the Pacific today. This diversity was achieved through influxes of puffins from the Pacific; the later loss of species was due to major oceanographic changes in the late Pliocene due to closure of the Panamanian Seaway and the onset of severe glacial cycles in the North Atlantic.
Friday, 12 June 2020
OLENELLUS OF THE EAGER FORMATION
Olenellus are a genus of trilobites — extinct arthropods — common in but restricted to Early Cambrian rocks some 542 million to 521 million years old and thus a useful guide fossil for the Early Cambrian. Olenellus had a well-developed head, large and crescentic eyes, and a poorly developed, small tail. The fellow you see had a bit of his tail crushed as he turned to stone.
This specimen of Olenellus is from the Lower Cambrian Eager Formation of British Columbia and is typical of the group. He's from the Rifle Range outcrop near Cranbrook.
Thursday, 11 June 2020
PORTUNOID CRAB
Tuesday, 9 June 2020
THE ELEPHANT BIRDS OF MADAGASCAR
Aepyornis skeleton, Monnier, 1913 |
Riding the movements of the Earth's crust, Madagascar, along with India, first split from Africa and South America and then from Australia and Antarctica, and started heading north. India eventually smashed into Asia — forming the Himalayas in the process — but Madagascar broke away from India and was marooned in the Indian Ocean. Madagascar has been on its own for the past 88 million years.
Elephant birds are members of the extinct ratite family Aepyornithidae, made up of large to enormous flightless birds that once lived on the island of Madagascar. A ratite is any of a diverse group of flightless and mostly large and long-legged birds of the infraclass Palaeognathae.
Elephant birds became extinct, around 1000–1200 CE, as a result of human hunting. Elephant birds comprised the genera Mullerornis, Vorombe and Aepyornis. While they were in close geographical proximity to the ostrich, their closest living relatives are the much smaller nocturnal Kiwi — found only in New Zealand — suggesting that ratites did not diversify by vicariance during the breakup of Gondwana but instead evolved from ancestors that dispersed more recently by flying.
Elephant birds were endemic to Madagascar. Phylogenetic, genetic, and fossil evidence all suggest that the elephant bird, along with the ostrich, arrived in Madagascar and India when these landmasses were still connected to Australia and Antarctica via a land bridge.
When India and Madagascar split, the elephant bird wound up surviving on Madagascar, while the ostrich was carried north with India and was eventually introduced to Eurasia when India collided with the continent. The presence of the elephant bird on Madagascar can be chalked up to vicariance; it was living on Madagascar land already when Madagascar broke off from India. Most of the species on Madagascar today seem to be descended from individuals that dispersed from Africa long after Madagascar was established as a separate island.
Photo: Aepyornis skeleton. Quaternary of Madagascar by Monnier, 1913 by Monnier - http://digimorph.org/specimens/Aepyornis_maximus/Aepyornis.phtml digimorph.org, Public Domain, https://commons.wikimedia.org/w/index.php?curid=79655
Image: Size of Aepyornis maximus (centre, in purple) compared to a human, an ostrich (second from right, in maroon), and some non-avian theropod dinosaurs. Grid spacings are 1.0 m by Matt Martyniuk.
Cooper, A., Lalueza-Fox, C., Anderson, S., Rambaut, A., Austin, J., and Ward, R. (2001). Complete mitochondrial genome sequences of two extinct moas clarify ratite evolution. Nature 409:704-707.
Goodman, S. M., and Benstead, J. P. (2005). Updated estimates of biotic diversity and endemism for Madagascar. Oryx 39(1):73-77.
Evolution Berkeley: https://evolution.berkeley.edu/evolibrary/news/091001_madagascar
Vences, M., Wollenberg, K. C., Vieites, D. R., and Lees, D. C. (2009). Madagascar as a model region of species diversification. Trends in Ecology and Evolution 24(8):456-465.
Monday, 8 June 2020
URSUS CURIOUS: TLA'YI
The animals are known for their ability to spray a liquid with a strong, unpleasant smell. Generally, the aroma from a skunk is enough of a deterrent to keep curiosity at bay. Not in this case.
Bear cubs are known for being playful and altogether too curious. Born in January, they usually stick pretty close to Mamma for the first two years of their lives 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. Yearlings are usually quite skittish, spending their time hidden up in trees. By the end of the summer, they grow into confident little bears. The karma gods were good to this wee one. Nobody was skunked in this quest for exploration, though not for lack of trying.
Sunday, 7 June 2020
ELEPHANT SHREW
These small, quadrupedal, insectivorous mammals strongly resemble rodents or opossums with their scaly tails, elongated snouts, and rather longish legs.
They live in the desert and temperate grasslands of southern Africa. The Elephant shrew is considered "Living Fossils" as their distinctive morphology has not changed all that much in the past 30 million years. They ought to have been named Elephant Bunny shrew. They move through the world like wee baby elephant-bunnies, snuffling on all fours and hopping about looking for tasty snacks. They have a preference for seeds, fruit, termites and berries. They know how to live well, taking a siesta each afternoon when the sun gets high in the sky.
Thursday, 4 June 2020
BASILEMYS FORELIMB
Basilemys is an extinct genus of early terrestrial or land turtles belonging to the family Nanhsiungchelyideae. They had a carapace similar in shape to aquatic turtles but limps and beak closer to terrestrial herbivores.
Today, these lovelies live in the Hell Creek floodplains munching on bits of grass and swamp plants. They are ectotherms, cold-blooded, reptiles and amniotes — they breathed air and did not lay eggs underwater but came to shore similar to modern turtles. They are known from Cretaceous deposits in North America and Asia. We've got some lovely examples from the Horseshoe Canyon Formation in Alberta and the Sustut Basin in northern British Columbia. Fossil remains of Basilemys have also been found in Saskatchewan, China, Kazakhstan, Mexico, Mongolia, the United States in California, Colorado, Montana, New Mexico, North Dakota, South Dakota, Texas, Utah, Wyoming and Uzbekistan from 144 collections and 152 occurrences. Photo credit: Joe Sertich
Wednesday, 3 June 2020
BASILEMYS: FRESHWATER TURTLE
You'll recall we've found Basilemys in the Sustut Basin of northern British Columbia. These two finds allow us to make some correlations on what was happening during the Upper Cretaceous in BC and Alberta.
The species Mallon and Brinkman wrote up is intermediate in age between the Campanian forms B. variolosa and B. gaffneyi and the upper Maastrichtian forms B. sinuosa and B. praeclara. It is also intermediate in its morphology, possessing a unique suite of both plesiomorphic — divided extragulars — and derived, square epiplastral beak, pygal wider than long, traits.
The Horseshoe Canyon specimen also boasts an autapomorphic square cervical scale. Phylogenetic analysis assuming parsimony recovers B. morrinensis in a polytomy with B. variolosa and B. gaffneyi, outside the clade formed by the upper Maastrichtian forms B. sinuosa and B. praeclara. The holotype of Basilemys morrinensis provides the first evidence that this genus reached a fairly large size, sometimes over a meter in length in the Horseshoe Canyon Formation, so not as small as previously thought based on less complete shell material.
Although Basilemys is usually regarded as terrestrial based on its skull and limb morphology, this specimen has a shell with a low profile — a derived hydrodynamic feature usually indicative of an aquatic mode of life.
The Horseshoe Canyon specimen was found with well-preserved fossils of Equisetum or horsetail. The Basilemys from Sustut was also found in association with plant fossils. So, aquatic, yes. But swampy freshwater aquatic. Or perhaps wet woods and the peripheries of water bodies — lakes, rivers, ponds. We know horsetails prefer a moist location and it appears our dear Basilymys did also.
Image One: Basilemys morrinensis, CMN 57059, shell, in A, dorsal, B, ventral, C, right lateral, and D, anterior views. Photo: Donald B. Brinkman
Image Two: Depositional context of CMN 57059. Segmented stalks of Equisetum cf. E. perlaevigatum (marked by arrowheads) found associated with shell. B, CMN 57059 as it was originally uncovered in the field (CMN negative #61554). Scale bar equals 8 cm (A). Photo: Donald B. Brinkman
Mallon, J. C., and D. B. Brinkman. 2018. Basilemys morrinensis, a new species of nanhsiungchelyid turtle from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta, Canada. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1431922.
Wednesday, 27 May 2020
BOTTLENOSE DOLPHINS
They have lungs, inhaling and exhaling through a blowhole at the top of their heads instead of a through their nose.
Dolphins 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. They are also quite vocal, making a lot of interesting noises in the water. They squeak, squawk and use body language — leaping from the water while snapping their jaws and slapping their tails on the surface. They love to blow bubbles, will swim right up to you for a kiss and cuddle. 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.
Tuesday, 26 May 2020
GRAY WHALES: ESCHRICHTIUS ROBUSTUS
Young Gray Whale, Eschrichtius robustus |
Two Pacific Ocean populations are known to exist: one of about 200 individuals whose migratory route is presumed to be between the Sea of Okhotsk off Russia's south coast and southern Korea, and a larger one with a population of about 27,000 individuals in the eastern Pacific.
This second group are the ones we see off the shores of British Columbia as they travel the waters from northernmost Alaska down to Baja California. Gray whale mothers make this journey accompanied by their calves, hugging the shore in shallow kelp beds and providing rare but welcome glimpses of this beauty.
The gray whale is traditionally placed as the only living species in its genus and family, Eschrichtius and Eschrichtiidae, but an extinct species was discovered and placed in the genus in 2017 — the Akishima whale, E. akishimaensis. Some recent DNA analyses suggest that certain rorquals of the family Balaenopteridae, such as the humpback whale, Megaptera novaeangliae, and fin whale, Balaenoptera physalus, are more closely related to the gray whale than they are to some other rorquals, such as minke. Still, others place gray whales as outside the rorqual clade, a kissing cousin if you will.
John Edward Gray placed it in its own genus in 1865, naming it in honour of physician and zoologist Daniel Frederik Eschricht. The common name of the whale comes from its colouration. The subfossil remains of now-extinct gray whales from the Atlantic coasts of England and Sweden were used by Gray to make the first scientific description of a species then surviving only in Pacific waters. The living Pacific species was described by American palaeontologist, Edward Drinker Cope as Rhachianectes glaucus in 1869.
Fin Whale, Balaenoptera physalus |
In 1993, a twenty-seven million-year-old specimen was discovered in deposits in Washington state that represents a new species of early baleen whale. It is especially interesting as it is from a stage in the group’s evolutionary history when baleen whales transitioned from having teeth to filtering food with baleen bristles.
Visiting researcher Carlos Mauricio Peredo studied the fossil whale remains, publishing his research to solidify Sitsqwayk cornishorum (pronounced sits-quake) in the annals of history. The earliest baleen whales clearly had teeth, and clearly still used them. Modern baleen whales have no teeth and have instead evolved baleen plates for filter feeding. Look to the rather good close-up of this young Gray Whale here to see his baleen where once there was a toothy grin.
The baleen is the comb-like strainer that sits on the upper jaw of baleen whales and is used to filter food. We have to ponder when this evolutionary change —moving from teeth to baleen — occurred and what factors might have caused it. Traditionally, we have sought answers about the evolution of baleen whales by turning to two extinct groups: the aetiocetids and the eomysticetids.
The aetiocetids are small baleen whales that still have teeth, but they are very small, and it remains uncertain whether or not they used their teeth. In contrast, the eomysticetids are about the size of an adult Minke Whale and seem to have been much more akin to modern baleen whales; though it’s not certain if they had baleen. Baleen typically does not preserve in the fossil record being soft tissue; generally, only hard tissue, bones and teeth are fossilized.
Sunday, 24 May 2020
USING BARNACLES TO TRACK ANCIENT WHALES
It is through the study of fossil barnacles that are roughly 270,000 million years old that help track ancient whale migrations. University of California Berkeley doctoral student Larry Taylor, the lead author of the study, published March 25, 2019, in the peer-reviewed journal Proceedings of the National Academy of Sciences published on some clever findings.
The barnacles not only record details about the whales’ yearly travels but also retain this information after they become fossilized. By following this barnacle trail, Taylor et al. were able to reconstruct migration routes of whales from millions of years in the past.
Today, Humpback whales come from both the Southern Hemisphere (July to October with over 2,000 whales) and the Northern Hemisphere (December to March about 450 whales along Central America) to Panama (and Costa Rica). They undertake annual migrations from polar summer feeding grounds to winter calving and nursery grounds in subtropical and tropical coastal waters.
One surprise find is that the coast of Panama has been a meeting ground for humpback whales going back at least 270,000 years.
To see how the barnacles have travelled through the migration routes of ancient whales, the team used oxygen isotope ratios in barnacle shells and measured how they changed over time with ocean conditions. Did the whale migrate to warmer breeding grounds or colder feeding grounds? Barnacles retain this information even after they fall off the whale, sink to the ocean bottom, and become fossils. As a result, the travels of fossilized barnacles can serve as a proxy for the journeys of whales in the distant past.
Barnacles can play an important role in estimating paleo-water depths. The degree of disarticulation of fossils suggests the distance they have been transported, and since many species have narrow ranges of water depths, it can be assumed that the animals lived in shallow water and broke up as they were washed down-slope. The completeness of fossils, and nature of the damage, can thus be used to constrain the tectonic history of regions.
Friday, 22 May 2020
MANATEES AND DUGONGS
They shared a cousin in the Steller's sea cow, Hydrodamalis gigas, but that piece of their lineage was hunted to extinction by our species in the 18th century. Dugongs have tail flukes with pointed tips and manatees have paddle-shaped tails, similar to a Canadian Beaver.
Both of these lovelies from the order Sirenia went from terrestrial to marine, taking to the water in search of more prosperous pastures, as it were. They are the extant and extinct forms of the oddball manatees and dugongs.
We find dugongs today in waters near northern Australia and parts of the Indian and Pacific Oceans. They inhabit rivers and shallow coastal waters, making the best use of their fusiform bodies that lack dorsal fins and hind limbs. I have been thinking about them in the context of some of the primitive armoured fish we find in the Chengjiang biota of China, specifically those primitive species that were also fusiform.
They favour locations where seagrass, their food of choice, grows plentiful and they eat it roots and all. While seagrass low in fibre, high in nitrogen, and easily digestible is preferred, dugongs will also dine on lower grade seagrass, algae, and invertebrates should the opportunity arise. They've been known to eat jellyfish, sea squirts, and shellfish over the course of their long lives. Some of the oldest dugongs have been known to live 70+ years, which is another statistic I find surprising. They are large, passive, have poor eyesight, and look pretty tasty floating in the water; a defenceless floating buffet. Their population is in decline and yet they live on.
Wednesday, 20 May 2020
ANTHOZOA: CORALS
Corals are important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.
A coral "group" is a colony of a myriad of genetically identical polyps. Each polyp is a sac-like animal typically only a few millimetres in diameter and a few centimetres in length. A set of tentacles surround a central mouth opening. Each polyp excretes an exoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously overnight, often around a full moon. Fertilized eggs form planulae, a mobile early form of the coral polyp which when mature settles to form a new colony.
Although some corals are able to catch plankton and small fish using stinging cells on their tentacles, most corals obtain the majority of their energy and nutrients from photosynthetic unicellular dinoflagellates of the genus Symbiodinium that live within their tissues. These are commonly known as zooxanthellae and gives the coral colour. Such corals require sunlight and grow in clear, shallow water, typically at depths less than 60 metres (200 ft). Corals are major contributors to the physical structure of the coral reefs that develop in tropical and subtropical waters, such as the Great Barrier Reef off the coast of Australia. These corals are increasingly at risk of bleaching events where polyps expel the zooxanthellae in response to stress such as high water temperature or toxins.
Other corals do not rely on zooxanthellae and can live globally in much deeper water, such as the cold-water genus Lophelia which can survive as deep as 3,300 metres (10,800 ft). Some have been found as far north as the Darwin Mounds, northwest of Cape Wrath, Scotland, and others off the coast of Washington State and the Aleutian Islands.
Tuesday, 19 May 2020
CANGREJO FÓSIL: COSTACOPLUMA
Chitin is a polysaccharide — a large molecule made of many smaller monosaccharides or simple sugars, like glucose. It's handy stuff, forming crystalline nanofibrils or whiskers.
Chitin is actually the second most abundant polysaccharide after cellulose. It's interesting as we usually think of these molecules in the context of their sugary context but they build many other very useful things in nature — not the least of these are the hard outer shells or exoskeletons of our crustacean friends. There have been some wonderful studies published of late on the cuticular structure of crabs and in particular the Late Maastrichtian crab, Costacopluma mexicana, from deposits near the town of from near Paredón, Ramos Arizpe in what is now southern Coahuila (formerly Coahuila de Zaragoza), in north-eastern Mexico. We see this same species in the Upper Cretaceous Moyenne of Northeast Morocco and from the Pacific slope, Paleocene of California, USA. This beauty is in the collection of José F. Ventura.
While the crustacean cuticle has been the subject of study for over 250 years (Reaumur, 1712, in Drach, 1939), the focus of that early work has been the process of moulting. Because crabs and other crustaceans have a hard outer shell (the exoskeleton) that does not grow, they must shed their shells through a process called moulting. Just as we outgrow our shoes, crabs outgrow their shells.
In 1984, Roer and Dillaman took a whole new approach, instead looking at the exoskeleton as a mineralized tissue. The integument of decapod crustaceans consists of an outer epicuticle, an exocuticle, an endocuticle and an inner membranous layer underlain by the hypodermis. The outer three layers of the cuticle are calcified.
The mineral is in the form of calcite crystals and amorphous calcium carbonate. In the epicuticle, the mineral is in the form of spherulitic calcite islands surrounded by the lipid-protein matrix. In the exo- and endo-cuticles the calcite crystal aggregates are interspersed with chitin-protein fibres which are organized in lamellae. In some species, the organization of the mineral mirrors that of the organic fibres, but such is not the case in certain cuticular regions in the xanthid crabs.
Control of crystal organization is a complex phenomenon unrelated to the gross morphology of the matrix. Since the cuticle is periodically moulted to allow for growth, this necessitates a bidirectional movement of calcium into the cuticle during post-moult and out during premolt resorption of the cuticle.
These movements are accomplished by active transport affected by a Ca-ATPase and Na/Ca exchange mechanism. The epi- and exo-cuticular layers of the new cuticle are elaborated during pre-moult but do not calcify until the old cuticle is shed. This phenomenon also occurs in vitro in the cuticle devoid of living tissue and implies an alteration of the nucleating sites of the cuticle in the course of the moult.
We're still learning about the relationship between the mineral and the organic components of the cuticle, both regarding the determination of crystal morphology and about nucleation. While the Portunidae offers some knowledge of the mechanisms and pathways for calcium movement, we know nothing concerning the transport of carbonate. These latter areas of investigation will prove fertile ground for future work; work which will provide information not only on the physiology of Crustacea but also on the basic principles of mineralization. I'm interested to see what insights will be revealed in the years to come. Certainly, the bidirectional nature of mineral transport and the sharp temporal transitions in the nucleating ability of the cuticular matrix provide ideal systems in which to study these aspects of calcification.
Torrey Nyborg, Francisco J. Vega and Harry F. Filkorn, Boletín de la Sociedad Geológica Mexicana, Vol. 61, No. 2, Número especial XI Congreso Nacional de Paleontología, Juriquilla 2009 (2009), pp. 203-209. Coahuila paleo coordinates:25°32′26″N 100°57′2″W
Monday, 18 May 2020
CRABS AND CHITIN
Crabs build their shells from highly mineralized chitin. Chitin gets around. It is the main structural component of the exoskeletons of many of our crustacean and insect friends. Shrimp, crab, and lobster all use it to build their exoskeletons.
Chitin is a polysaccharide — a large molecule made of many smaller monosaccharides or simple sugars, like glucose. It's handy stuff, forming crystalline nanofibrils or whiskers. Chitin is actually the second most abundant polysaccharide after cellulose. It's interesting as we usually think of these molecules in the context of their sugary context but they build many other very useful things in nature — not the least of these are the hard shells or exoskeletons of our crustacean friends.
Sunday, 17 May 2020
PROTOEASTER NODOSUS
These beauties are commonly known as Horned Sea Stars or, my personal favorite, Chocolate Chip Sea Stars.
They are part of the class Asteroidea (starfish or sea stars) one of the most diverse groups within the phylum Echinodermata and have a lengthy lineage in the fossil record stretching all the way back to the Triassic. These echinoderms make a living on near-shore sandy bottoms or lurk in the seagrass meadows of some of our most beautiful waters.
Chocolate Chip Sea Stars live in the waters off the Philippine Sea, off the coast of Australia and New Guinea. Their range extends to the Marshall Islands through central and southeastern Polynesia, past Easter Island and all the way up to Hawaii. Pretty much pick any of the top contenders for a warm, tropical vacation and they've beaten you to it!
This species of sea star has black rows of "horns" or "spines" meant to scare off predators. A noble deterrent for his fishy friends but I find this signature decoration rather fetching. These fellows like to graze on choice corals and sponges. They are also happy to make a meal of snails and bitter sea urchins when these ambrosial treats are presented. And they are social, both to mate, gathering in groups to aid in fertilization and acting as a softcover for shrimp, wee brittle stars and juvenile leatherjackets or filefish, who tuck in and enjoy the protective cover of those dark nodes.
Friday, 15 May 2020
SOUTH AMERICAN TAPIR
South American Tapir, Tapirus terrestris |
He's a water baby and a relative of the rhinoceros. Tapir love the water. They play, swim, dive, and use it to protect themselves from predators.
Their feet are specially designed for swimming and walking on muddy shores. Each of their front feet has four splayed toes, a bit like having a fin or snowshoe on your feet. Their back feet have a similar design but with three toes. They nap and hide in the forest during the day and then head out at night to munch on leaves, shoots, fruit, and other green goodies in the Amazon Rainforest and the River Basin in South America, east of the Andes.
They can be found in Venezuela, Colombia, and the Guianas in the north to Brazil, Argentina, and Paraguay in the south, to Bolivia, Peru, and Ecuador in the west. Three species of Tapir call Columbia home and much of the scientific research is focussed on this area. They're also hiring if you'd like to get more involved. While many find them adorable, sadly, they are also appreciated for their beautiful coats. Their dwindling numbers are largely due to poaching for their meat and hide, as well as habitat destruction. If I had the means, I'd buy up a big chunk of land where they could roam free. Some folks are helping and you can, too. There is a Tapir Preservation Fund set-up to aid these cuties with additional habitat. I'll pop the link here so you can check them out. They have a Facebook page and on it, there is the sweetest video of a Tapir sitting in the waves watching the sunset. Do check it out. It's very sweet.
Tapir Specialist Group: https://tapirs.org/conservation/tsgcf/
TSG Brazil: Rua Lindóia, 79046-150 Campo Grande, Brazil / +55 67 3344-0240
Thursday, 14 May 2020
DRIFTWOOD CANYON: FOSSIL TAPIRS, HEDGEHOGS, BIRDS & FLOWERS
Early Eocene Tapir from Driftwood Canyon |
Today, Driftwood Provincial Park is about halfway between Prince George and Prince Rupert near the town of Smithers. The rocks that make up the strata here started out further to the south, riding geologic plates to their current location.
Along with the Tapir and a rather sweet hedgehog, we also find birds, insects, and a huge variety of fossil plants in these outcrops. Fossils of plant remains are rare but include up to 29 genera. The most common plant fossils found are leafy shoots of the dawn redwood, Metasequoia, and the floating fern Azolla primaeva as mats of plants or as isolated fossils.
Fossil fish from Driftwood Canyon in the Canadian Museum of Nature includes specimens collected in the 1930s; however, Driftwood Canyon fossils have only been studied since the 1950s.
The Driftwood Canyon fossil beds are best known for the abundant and well-preserved insect and fish fossils (Amia, Amyzon, and Eosalmo). The insects are particularly diverse and well preserved and include water striders (Gerridae), aphids (Aphididae), leafhoppers (Cicadellidae), green lacewings (Neuroptera), spittlebugs (Cercopidae), march flies (Bibionidae), scorpionflies (Mecoptera), fungus gnats (Mycetophilidae), snout beetles (Curculionidae), and ichneumon wasps.
A fossil species of green lacewing (Neuroptera, Chrysopidae) was recently named Pseudochrysopa harveyi to honour the founder of the park, Gordon Harvey. Fossil feathers are sometimes found and rare rodent bones are sometimes found in fish coprolites. Most recently, fossil palm beetles (Bruchidae) were described from the beds, confirming the presence of palms (Arecaceae) in the local environment in the early Eocene.
Alder, Alnus sp., still common today are also found, as well as the leaves or needles and seeds of pines, Pinus sp., the golden larch, Pseudolarix sp., cedars, Chamaecyparis and/or Thuja spp., redwood Sequoia sp., and rare Ginkgo and sassafras, Sassafras hesperia, leaves. A lovely permineralized pine cone Pinus driftwoodensis and associated 2-needle foliage were described from the site in the 1980s.
Rare flowers and the seeds of flowering plants have been collected, including Ulmus, Florissantia, and Dipteronia, a genus of trees related to maples, Acer. spp., that today grows in eastern Asia.
If you fancy a trip to Driftwood Canyon Provincial Park, follow Driftwood Road from Provincial Highway 16. A car park just off the road access leads to an interpretive sign and a bridge across Driftwood Creek. A short interpretive trail leads visitors to a cliff-face exposure of Eocene shales. Signate speaks to how these beds were deposited in an inter-montane lake. Interbedded within the shales are volcanic ash beds, the result of area volcanoes that were erupting throughout the life of the Eocene lake that produced the shales.
Wednesday, 13 May 2020
WOLVERINE RIVER DINOSAUR TRACKS
Jen Becker, British Columbia Paleontological Alliance Field Trip |
There are two types of footprints at the Wolverine River Trackside –theropods (at least four different sizes) and ankylosaurs. The prints featured in this photo were laid down by some lumbering ankylosaurs out for a stroll in soft mud. Many of the prints are so shallow that they can only be recognized by the skin impressions pressed into the mud. We'd been up to the fossil sites in the day but wanted to come back in the evening to see them by lamplight. After a lovely dinner, we hiked up to Wolverine in the dark. We filled the tracks with water and lit them with warm yellow lamplight. Some clever soul brought a sound system and played spooky animal calls to add prehistoric ambiance. A truly amazing evening.
Tuesday, 12 May 2020
DARWIN AND THE GREAT DEBATE
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.
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 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.
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.
Sunday, 10 May 2020
CRETACEOUS HADROSAUR FROM ALBERTA
When you scour the badlands of southern Alberta, most of the dinosaur material you'll find are from hadrosaurs. These lovely tree-less valleys make for excellent-searching grounds and have led us to know more about hadrosaur anatomy, evolution, and paleobiology than for most other dinosaurs.
We have oodles of very tasty specimens and data to work with. We've got great skin impressions and scale patterns from at least ten species and interesting pathological specimens that provide valuable insights into hadrosaur behaviour. Locally, we have an excellent specimen you can visit in the Courtenay and District Museum on Vancouver Island, Canada. The first hadrosaur bones were found on Vancouver Island a few years back by Mike Trask, VIPS, on the Trent River near Courtenay.
The Courtenay hadrosaur is a first in British Columbia, but our sister province of Alberta has them en masse. Given the ideal collecting grounds, many of the papers on hadrosaurs focus on our Canadian finds. These herbivorous beauties are also found in Europe, South America, Mexico, Mongolia, China, and Russia. Hadrosaurs had teeth arranged in stacks designed for grinding and crushing, similar to how you might picture a cow munching away on the grass in a field. These complex rows of "dental batteries" contained up to 300 individual teeth in each jaw ramus. But even with this great number, we rarely see them as individual specimens.
They didn't appear to shed them all that often. Older teeth that are normally shed in our general understanding of vertebrate dentition, were resorped, meaning that their wee osteoclasts broke down the tooth tissue and reabsorbed the yummy minerals and calcium.
As the deeply awesome Mike Boyd notes, "this is an especially lucky find as hadrosaurs did not normally shed so much as a tooth, except as the result of an accident when feeding or after death. Typically, these fascinating dinosaurs ground away their teeth... almost to nothing."
In hadrosaurs, the root of the tooth formed part of the grinding surface as opposed to a crown covering over the core of the tooth. And curiously, they developed this dental arrangement from their embryonic state, through to hatchling then full adult.
There's some great research being done by Aaron LeBlanc, Robert R. Reisz, David C. Evans and Alida M. Bailleul. They published in BMC Evolutionary Biology on work that looks at the histology of hadrosaurid teeth analyzing them through cross-sections. Jon Tennant did a nice summary of their research. I've included both a link to the original journal article and Jon Tennant's blog below.
LeBlanc et al. are one of the first teams to look at the development of the tissues making up hadrosaur teeth, analyzing the tissue and growth series (like rings of a tree) to see just how these complex tooth batteries formed.
They undertook the first comprehensive, tissue-level study of dental ontogeny in hadrosaurids using several intact maxillary and dentary batteries and compared them to sections of other archosaurs and mammals. They used these comparisons to pinpoint shifts in the ancestral reptilian pattern of tooth ontogeny that allowed hadrosaurids to form complex dental batteries.
References:
LeBlanc et al. (2016) Ontogeny reveals function and evolution of the hadrosaurid dinosaur dental battery, BMC Evolutionary Biology. 16:152, DOI 10.1186/s12862-016-0721-1 (OA link)
To read more from Jon Tennant, visit: https://blogs.plos.org/paleocomm/2016/09/14/all-the-better-to-chew-you-with-my-dear/
Photo credit: Derrick Kersey. For more awesome fossil photos like this from Derrick, visit his page: https://www.facebook.com/prehistoricexpedition/
Thursday, 7 May 2020
ANCIENT SWAMPS AND SOLAR FLARES
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 formed by a natural process — the anaerobic decomposition of buried dead organisms. These plants and algae lived and died many millions of years ago, but while they lived, they soaked up and stored energy from the sun through 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, the pressure turns the mud mixed with 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...
Burning fossil fuels, like oil and coal, releases large amounts of carbon dioxide and other gases into the atmosphere. They get trapped as heat, which we call the greenhouse effect. This plays havoc with global weather patterns and our world does not do so well when that happens.
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 material that formed it millions of years ago. 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 — which smells like rotting eggs — oxygen and nitrogen thrown in.
It is just that the long-ago rain forest 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 rain forest 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 rain forests 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.
Wednesday, 6 May 2020
ZENASPIS PODOLICA OF THE UKRAINE
Podolia or Podilia is 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 420 million-year-old remains of ichthyofauna can be found near the surface, making them accessible to collection and study. Zenaspis is an extinct genus of jawless fish which thrived during the early Devonian. Being jawless, Zenaspis was probably a bottom feeder, snicking on debris from the seafloor similar to how flounder, groupers, bass and other bottom-feeding fish make a living.
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, the faunal list of Early Devonian agnathans and fishes from Podolia number seventy-two species, including 8 Thelodonti, 39 Heterostraci, 19 Osteostraci, 4 Placodermi, 1 Acanthodii, and 1 Holocephali (Voichyshyn 2001a).
In Podolia, the Lower Devonian Redbeds strata (the Old Red Formation or Dniester Series) are 1800 metres thick and range from Lochkovian to Eifelian in age (Narbutas 1984; Drygant 2000, 2003).
In their lower part, the Ustechko and Khmeleva members of the Dniester Series, they consist of lovely multicoloured, mainly red, fine-grained cross-bedded massive quartz sandstones and siltstones with seams of argillites (Drygant 2000).
We see fossils 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 the awesome Fossilero Fisherman.