Thursday, March 19, 2020

Biography of Sir Arthur Currie

Biography of Sir Arthur Currie Sir Arthur Currie was the first Canadian-appointed commander of the Canadian Corps in World War I. Arthur Currie participated in all major actions of the Canadian forces in World War I, including the planning and execution of the assault on Vimy Ridge. Arthur Currie is best known for his leadership during the last 100 Days of World War I and as a successful advocate of keeping Canadians together as a unified fighting force. Birth December 5, 1875, in Napperton, Ontario Death November 30, 1933, in Montreal, Quebec Professions Teacher, real estate salesman, soldier and university administrator Career of Sir Arthur Currie Arthur Currie served in the Canadian Militia before World War I. He was sent to Europe at the outbreak of World War I in 1914. Arthur Currie was appointed the commander of the 2nd Canadian Infantry Brigade in 1914. He became commander of the 1st Canadian Division in 1915. In 1917 he was made commander of the Canadian Corps and later that year was promoted to the rank of lieutenant general. After the war, Sir Arthur Currie served as Inspector General of the Militia forces from 1919 to 1920. Currie was principal and vice-chancellor of McGill University from 1920 to 1933. Honors Received by Sir Arthur Currie Commander of the BathLegion of HonourKnight Commander of the Order of St. Michael and St. GeorgeCroix de GuerreU.S. Distinguished Service Medal

Tuesday, March 3, 2020

Dunkleosteus - Facts and Figures

Dunkleosteus - Facts and Figures Name: Dunkleosteus (Greek for Dunkles bone); pronounced dun-kul-OSS-tee-us Habitat: Shallow seas worldwide Historical Period: Late Devonian (380-360 million years ago) Size and Weight: About 30 feet long and 3-4 tons Diet: Marine animals Distinguishing Characteristics: Large size; lack of teeth; thick armor plating About Dunkleosteus The marine animals of the Devonian periodover 100 million years before the first dinosaurstended to be small and meek, but Dunkleosteus was the exception that proved the rule. This huge (about 30 feet long and three or four tons), armor-covered prehistoric fish was probably the largest vertebrate of its day, and almost certainly the largest fish of the Devonian seas. Reconstructions can be a bit fanciful, but Dunkleosteus likely resembled a large, underwater tank, with a thick body, bulging head, and massive, toothless jaws. Dunkleosteus wouldnt have had to be a particularly good swimmer, since its bony armor would have been sufficient defense against the smaller, predatory sharks and fish of its briny habitat, such as Cladoselache. Because so many fossils of Dunkleosteus have been discovered, paleontologists know a good deal about the behavior and physiology of this prehistoric fish. For example, theres some evidence that individuals of this genus occasionally cannibalized each other when prey fish ran low, and an analysis of Dunkleosteus jawbones has demonstrated that this vertebrate could bite with a force of about 8,000 pounds per square inch, putting it in a league with both the much later Tyrannosaurus Rex and the much later giant shark Megalodon. (By the way, if the name Dunkleosteus sounds funny, thats because it was named in 1958 after David Dunkle, a curator at the Cleveland Museum of Natural History.) Dunkleosteus is known by about 10 species, which have been excavated in North America, western Europe, and northern Africa. The type species, D. terrelli, has been discovered in various U.S. states, including Texas, California, Pennsylvania and Ohio. D. belgicus hails from Belgium, D. marsaisi from Morocco (though this species may one day be synonymized with another genus of armored fish, Eastmanosteus), and D. amblyodoratus was discovered in Canada; other, smaller species were native to states as far afield as New York and Missouri. (As you might have guessed, we can attribute the profusion of Dunkleosteus remains to the fact that heavily armored skin tends to persist unusually well in the fossil record!) Given the near-worldwide success of Dunklesteus 360 million years ago, the obvious question presents itself: why did this armored fish go extinct by the start of the Carboniferous period, along with its placoderm cousins? The most likely explanation is that these vertebrates succumbed to changes in ocean conditions during the so-called Hangenberg Event, which caused marine oxygen levels to plungean event that definitely would not have favored multi-ton fish like Dunkleosteus. Secondarily, Dunkleosteus and its fellow placoderms may have been out-competed by smaller, sleeker bony fish and sharks, which went on to dominate the worlds oceans for tens of millions of years thereafter, until the advent of the marine reptiles of the Mesozoic Era.