Extinction of Dinosaurs
Many different theories exist as to why the dinosaurs went extinct. We know for sure most dinosaurs died out around 65 million years ago. The majority of scientists agree on a number of theories as to what brought the end of the dinosaurs. The most popular theory is that an asteroid ended the reign of the dinosaurs. Another theory, massive climate change in the pre-historic atmosphere, caused all the dinosaurs to die. Some scientists believe that mammals out competed dinosaurs for food and other resources. The last theory that dinosaurs died due to a large amount of volcanism comes up in scientists list of theories as well. Many different theories of why dinosaurs went extinct include extinction by asteroid, mammals outcompeting dinosaurs, climate change and volcanism.
The most popular theory of dinosaur extinction, the asteroid theory, says that dinosaurs died out because of a single, giant asteroid. They say that the asteroid that struck the earth near the Gulf of Mexico went 43,000 mph and spanned six miles wide (Erdman). When it hit the Earth the asteroid it left an enormous crater that measured 24 miles deep and 125 miles wide (Erdman). Just the impact of the asteroid destroyed the forests and landscape of the majority of North America due to its massive shock wave (Erdman). Many species went extinct when the asteroid hit, these species include dinosaurs, ammonites (certain ocean dwelling creatures), pterosaurs, and some plant groups dinosaurs, ammonites (mollusks related to the octopus and the chambered nautilus), pterosaurs, and certain plant groups. Although devastating, the asteroid did not wipe out all of the animals on Earth, it didn’t exterminate fish, frogs, turtles, birds, mammals and croco...
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The possibility if a meteor strike as the cause of extinctions is discarded, something that most specialists agree on. There is no evidence of any meteor crater big enough or recent enough to be accountable for it; there are no “elements that are common extraterrestrially but less so on Earth, such as iridium, and no sign of a tsunami or other phenomena following the impact.” The extinctions where also very selective and occurred over a very long period of time. If a “one shot” catastrophe had been the cause it would have affected all species at the same time and in similar
The question of what caused the extinction of megafauna during the Late Pleistocene period is one that archaeologists have struggled to answer for decades, but why should it matter? Discovering with certainty the cause of megafaunal extinction would simultaneously prove or disprove any of the proposed implications of each existing theory regarding this massive extinction.
The biggest mass extinction of the past 600 million years (My), the end-Permian event (251 My ago), witnessed the loss of as much as 95% of all species on Earth. Key questions for biologists concern what combination of environmental changes could possibly have had such a devastating effect, the scale and pattern of species loss, and the nature of the recovery. New studies on dating the event, contemporary volcanic activity, and the anatomy of the environmental crisis have changed our perspectives dramatically in the past five years. Evidence on causation is equivocal, with support for either an asteroid impact or mass volcanism, but the latter seems most probable.
The Permian-Triassic Extinction is a mass extinction that occurred between the Permian and Triassic geologic time periods approximately 250 million years ago; it is the deadliest of all extinctions that have occurred on Earth. In addition, during the Permian-Triassic extinction the continents of today existed as one supercontinent known as Pangaea. This was the first time in history where continental or land mass exceeded that of the ocean. This was also before dinosaurs of the Triassic period roamed Earth, during this time animals such as the therapsids, and Synapsids such as the Pelycosaurs, insects and amphibians also occupied Earth. Fauna that existed during the Permian period includes Gymnosperms, or seed producing plants such as the Conifers. Other animals that existed during this time include marine life such as brachiopods (clams), bryozoans (coral-like skeletons), bony fish and sharks, as well as crinoids (sea urchin like creatures). According to National Geographic, about 90 percent of all the animals and fauna of this period perished, the marine life was hit the hardest wi...
He explores the theories that a rise in temperature could have made the reptiles of old infertile, or that the dinosaurs ate flowering plants that acted as drugs, causing the beasts to overdose. He goes on to examine a third theory, that of an asteroid hitting the earth and causing a cloud of smoke and dust to cover the sun, dropping temperatures and killing not only the dinosaurs, but much of the life that was present on the Earth at the time. Gould himself leans toward the last theory, citing evidence and research to back his point. All of this, he delivers with an air of humor, saying things such as “How can we possibly decide whether the hypothesis of testicular frying is right or wrong?” (par 21). While the theory of infertility of dinosaurs comes from the idea of rising heat, Gould’s wording here brings to mind a funny image rather than a worldwide epidemic. Using humor again, Gould says “If you talk just about asteroids, dust, and darkness, you simply tell stories no better and no more entertaining than fried testicles or terminal trips” (par 26). Not only does he cast aside the first two theories as useless frivolities, he sets the stage for proving why the asteroid theory is better, using humorous language to do so. A humorous essay such as Gould’s is fun to read, while keeping a basis in
ix[9] Highfield, Roger. Dinosaur Extinction Theory ‘A Myth.’ The Telegraph – UK. March 1, 2004. Internet: http://www.rense.com/general49/tho.htm
“...99.9 per cent of all [species] that have ever existed are now extinct.” (Benton 1) After one hundred and sixty million years of domination, the reign of the dinosaurs ended in fire and ice. Sixty five million years ago, the largest volcanoes in the history of the Earth erupted across what is now India, effectively annihilating the dinosaurs by spewing out noxious gas and ash, that effectively blocked out the sun killing off most vegetation and breaking the food chain, leaving the dinosaurs to starve. Compared to other groups of animals the dinosaurs were the most vulnerable to such a climatic event and the result was the end of the dinosaurs’ glorious evolutionary history.
However, asteroids are much more deadly. If over-sized meteor can wreck buildings and injure people, then a normal sized asteroid can easily wipe out species if it lands in the right place. As mentioned before, asteroids are much bigger than meteor and much more rare. According to the “Mail Online” 12,000 years ago some type of asteroid slammed into the Northern Canada and some scientist believe that wiped off the mammoths and caused the “Younger Dryas”. Another famous event of asteroids striking, that many scientist believe, was around 65 million years ago asteroids rained and killed of all the dinosaurs 75% of all the life on earth.
Sex, drugs, and disasters are both popular topics that grab public attention and scientific theories of the extinction of dinosaurs. While sex and drug hypotheses represent silly speculations, the disaster claim is good science: it provides testable evidence, has an impact on other scientific fields, and generates continuous research.
Because dinosaurs are animals that lived millions of years ago, we are entirely dependent on the fossils that they have left behind for any understanding that we hope to gain. As any paleontologist will tell you, fossil hunting is difficult. There are no certainties, no guarantees. A certain amount of luck is as valuable as any scientific knowledge.
Dinosaurs held their own, according to studies, for at least 150 million years. After becoming extinct and finding fossilized remains dinosaurs have become a way in which we not only measure the changes that have occurred as the planet evolved, but also how we express ourselves today.
The most significant event of the Cretaceous era came at its end. Nearly 65 million years ago, the second most severe mass extinction in earth’s history occurred. This resulted in the loss of around 80% of species living at the time. Though nowhere near as severe as the end-Permian mass extinction, the end-Cretaceous extinction is the most well known mass extinction event. This is due to the violent event that caused it the extinction, as well as the chapter of earth’s history that it closed: the Dinosaurs. The Cretaceous Event ( often shortened to K-T event) Of the animals that were killed off were the flying reptiles (pterosaurs) and the last few mosasaurs and plesiosaurs, both early marine reptiles. Many mollusks and species of microscopic plankton were killed. Terrestrial plants suffered mass extinction as well. Almost 60% of terrestrial plants were lost. This led to high extinction rates among insect populations, especially insects that were highly specialized to feed on just a few types of plants had it the worst. It took approximately 9 million years for the global insect populations to recover from the Cretaceous extinction. Immediately after the extinction, the earth saw an explosion of short term species who respond well to fire, or other external disturbance. Evidence of the catastrophe comes from a thin rock layer deposited worldwide just after the impact. It is dominated by fossil plants whose descendants recover quickly after fires of other disturbances, such as Fire Weed in Alaska. The causes of the Cretaceous extinction are still being debated by paleontologists. Scientists agree that the main cause of the extinction was a...
seems like it happened so sudden, as geologic time goes, that almost all the dinosaurs
Almost 23% of all families, 48% of all genera (20% of marine families and 55% of marine genera) and 70% to 75% of all species went extinct (Beaz). Although the cause of this mass extinction is debatable, many speculate that global warming was the killer. Because Pangea was breaking up into Laurasia and Gondwanaland, there was widespread volcanic activity caused by the rifting, increasing atmospheric carbon dioxide. The massive release of this greenhouse gas increased global air temperatures and resulted in acidified oceans along with rising sea levels. If this is the case, the life in the ocean would have died at a significant rate. Many families of brachiopods, gastropods, bivalves, and marine reptiles became extinct (Rafferty). An important trace fossil known as the phylloceratid ammonoid was able to survive, and they gave rise to the explosive radiation of cephalopods later in the Jurassic Period, as well as evolved into many different forms during the later Cretaceous (End Triassic Extinction). This extinction event ranks fourth in severity of the five major extinction events over geologic history
Several mass extinctions have occurred during the Earth’s history. The Cretaceous – Tertiary Boundary (K-T) Extinction caused the loss of at least three-quarters of all species known at that time including the dinosaurs. The cause of this mass extinction is a controversial subject among scientists but the fossil evidence of it’s occurrence is abundant.