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The mass extinctions of the earths history
The mass extinctions of the earths history
Are we in a 6th mass extinction essay
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Our world is a great incubator of life, however it likes to go through periods of change where only those ready to adapt will survive. Five times already, our planet has gone through periods of mass species extinction, forcing those who want to survive to adapt and overcome. We are now facing a sixth major extinction, one not caused by a force of nature, but caused by a single species. We will take a look into the first five major extinction and then delve into the one that is ongoing right now.
The first major mass extinction occurred approximately 440 mya, and is known as the Ordovician–Silurian extinction event. This event was triggered by rapid cooling, and the corollary effect of the lower sea level from glaciers forming. Laurentian brachiopods were hit the hardest by this event as they lived in shallower sections of the ocean leaving them the most exposed by the event. As most life at this time existed in the shallow waters it is, easy to see why this was the second largest of the five major mass extinctions.
The second mass extinction occurred approximately 370 mya and is commonly referred to as the Late Devonian extinction. 70 million years later, we have more complex life, which has moved out of the ocean making use of the land. The Late Devonian extinction is not a single event but a myriad of smaller scale extinctions such as the Kellwasser event, and the Hangenberg event that are combined to create the entirety of the major extinction event.
The third mass extinction happened approximately 245 mya and is referred to as the Permian–Triassic extinction event. “More than half of the families of living things died out, and as many as 90 to 96 percent of the planet's marine species were lost. At the same time, p...
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...und 8.7 million. The number of species lost per year multiplied by 20 and then divided by the total number of species shows a total loss of approximately 7 percent of the world’s species. As climate change becomes more of an issue this should cause a rise in annual extinctions, which makes the sixth mass extinction to be an all too real scenario.
The next step is to look at the sixth mass extinction and see how it differs from the previous five. The five mass extinction events were natural occurrences in the environment that saw the more adaptive creatures survive during the interim where the earth balanced itself out. The sixth mass extinction is the first time where the loss of species, and the change in climate is due to a species. Hard to be mad at ants for making a mess of your house, when you are a member of the species responsible for a mass extinction.
In this paper Martin is arguing that late quaternary or near time extinctions where caused by human activity or as he calls it “overkill”. Martin recognizes that there have been many forces that have triggered extinctions in the planet on the past but disagrees with the idea that near time extinctions where caused by some commonly believed causes like climate change, disease or nutrient shortage. He argues that the arrival of humans to different continents, islands and the subsequent excessive hunting, the introduction of diseases and other competitors and predators was the cause of extinction of a great number of species “As our species spread to various continents we wiped out their large
There have been five mass extinctions over the last half-billion years while the sixth extinction is currently being examined by scientists around the world. Studies have shown that this is the most shocking and damaging event since the impact that caused the extinction of dinosaurs. This one is different from all others, because humans are the cause of this disaster to our current environment. If we don’t start to realize this issue and do something about it, eventually it will be too late to try to save the Earth and ourselves. I am going to analyze the sixth chapter, “The Sea Around Us,” for pathos, ethos, visual rhetoric and other related issues
“If you want to think about why humans are so dangerous to other species, you can picture a poacher in Africa carrying and Ak-47/ better still, you can picture yourself, holding a book on your lap” (Kolbert 266). This excerpt alone sets up the dark narrative that lies within The Sixth Extinction. It is uncomfortable to think about the impact that humans have on the environment on a global scale; however, it is nearly unbearable to recognize individual actions such as reading a book, directly contribute to the devastation of the earth.
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.
Throughout Earth’s history there have been many changes. These changes have consisted of temperature fluctuations, atmospheric differentiations, extinctions of various plant and animal life, etc. Over time everything seems to have evolved in some way form or fashion. However, the Permian Era extinction was different from all the rest. This extinction affected every form of life, but especially the marine life. Researchers have stated that 93-97% of all Earths species went extinct during this period of time. This essay will explain how a once blossoming progressive era turned into Earths most catastrophic event.
Long-term survival of a species depends on its ability to adapt to changing environmental conditions (Murphy, 1994). Genetic diversity within a species, which has taken 3.5 billion years to evolve, makes adaptations to these changing environments possible. Unfortunately, the rate of extinction of genetically diverse organisms is rapidly increasing, thus reducing this needed biodiversity, largely due to the human impacts of development and expansion. What was an average of one extinction per year before is now one extinction per hour and extinct species numbers are expected to reach approximately one million by the year 2000 (WWW site, Bio 65). As a result governmental and societal action must be taken immediately!
The disaster theory, Gould claims, is an example of good science. It has testable evidence and has an impact on studies in other fields of science, it develops further and explains why the extinction of dinosaurs occurred simultaneously with other events. This theory suggests that a large comet hit the Earth sixty five million years ago, causing the cloud of dust to rise into the sky and to block sunlight. As a result, world temperatures went down significantly, the ice age bega...
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...
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.
Earth has gone through five fully major extinctions before. We currently are in the process of Earth’s sixth mass extinction. This mass extinction is closely related in severity to the extinction of the dinosaurs. Earth’s extinctions are broken into three different areas. The first area was the large number of animals caught by hunter-gathers. The discovery of agriculture led to the second area of extinction, wildlife habitats. These wildlife habitats were destroyed due to humans starting to stay in one area.
Thousands of species have become extinct over the last four decades as a result of changes in land use and as a result of global warming. Whether or not the millions of species can adapt and evolve to climate changes is debatable. As this brief overview will report, the human species is not adapting well to the changes. It must be remembered that increases in the levels of carbon dioxide are certainly responsible for the risk many species face, but so is the way land is used, e.g., rain forest destruction. There is a feedback loop wherein plant life and the climate are interdependent. Each affects the other. When forests are cut down, temperatures in that area will rise. Rising temperatures cause other plant life requiring cooler temperatures To die off.
living on earth disappeared. So how did these dominant creatures just die off? Was it a
== = = Human beings are dependent on the Earth's diversity of species for our survival. Wild species play a vital role in the maintenance of the planets ecological functions, yet everyday on the planet 40-100 species become extinct.
Because the CO2 levels are rising, the ice caps are melting and many more animals can become extinct. When pangea started splitting, there was a lot of volcanic activity, which cause the death of many dinosaurs. A meteor also hit earth and the mass extinction of many land and marine animals happened. There have been five mass extinctions in Earth’s history. The worst one wiped out ninety-six percent of marine life and seventy percent of land organisms. This took millions of years to recover.