Riley 6 recognizable evidence for animals was discovered in Oman, this discovery revealed small sea sponges that were alive approximately 635 million years ago.” -Oldest fossil evidence for animals found. Nearing 443 million years ago occurred the third largest extinction in Earth’s history the Ordovician-Silurian extinction, during this extraordinary event almost 85% of all sea life had been wiped out. Preceding this event a giant formation of ice was collecting in the southern hemisphere. It was proposed that this sheet of ice had lowered sea levels and messed with ocean chemistry.
The Devonian Period was between 416 million and 358 million years ago. During this fundamental period sea life grew exponentially with the introduction of new organisms such as trilobites, and Placoderms (armored fishes). Towards the end of this period there was another mass extinction resulting in one third of all species on Earth becoming extinct this extinction is called the Late Devonian extinction. The best possible cause of this was an impact event caused by a huge meteor. With left the oceans in a state devoid of oxygen the only possible creature able to
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However, it would not be until the dinosaurs went extinct that the mammals would flourish. The evolution of the first mammals had occurred towards the end of the triassic period. Their ancestor who can link this evolution to is the therapsids. The first mammals were small, which was an advantage during the time of the dinosaurs. Since nearly all of the carnivorous dinosaurs were large, the smaller the mammal the more likely it will survive. The extinction of the dinosaurs was most likely caused by a huge meteor colliding with the Earth which is known as the Cretaceous-Tertiary extinction extinction. This
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
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 eradication of species numbers average at a toll close to one hundred percent of earths total living creatures. “It is the Earth's most severe known extinction event, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct” (Sahney, and Benton 759). Not only where marine and terrestrial species effected but this catastrophic event is the only recogni...
Extinctions happen everywhere on the world that has increasingly fluctuating weather. Before the Industrial Revolution, the days prior to humans pumping the atmosphere with greenhouse gases, the earth was moderately temperate. Today, the average temperature is 64° F, almost 10° F above normal. Because of the climate change, the polar caps are melting, making the Artic inhospitable to a serious of taxonomic groups, which are now in danger of extinction. Since all the glaciers are thawing, the newly liquefied water is flooding into the oceans. The sea-level rise devastates coastally ecology, erodes beaches, and floods agriculture land. This affects the habitats of plants, birds, and sea life, meaning they no longer have a safe place to have their young. With no new offspring, the species cease to exist. The continents most affected by the Holocene extinction are North and South America because that is where a majority of the megafauna lived thousand of years ago; of these was the Woolly mammoth. In the 1800’s, the ecosystem (over hunted and deforested) was not resilient enough to protect themselves from the industrial e...
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.
Some studies have found “that atmospheric CO2 concentration is approximately 383 parts per million by volume (ppmv), a level not seen in at least 650,000 years, and it is projected to increase by 0.5% per year throughout the 21st century.” (Guinotte) “This is because…the ocean absorbs about a third of fossil fuel emissions, but this amount is likely to increase to 90% in the future.” (Bralower) As a result, “the chemistry of the world's oceans is changing at a rate not seen for 65 million years, with far-reaching implications for marine biodiversity and food security, according to a new United Nations study...” (Knight) “…This change is cause for serious concern [for] many marine organisms…, [because they] may not be able to adapt quickly enough to survive these changes.” (Guinotte)
Fossil records from 12,000 years ago show the appearance of the Large Mammals followed by Paleoindian in Eastern North America. Another piece of the fossil record shows that the appearance of Paleoindian brought about the disappearance of the large mammals. Some people feel that, "there is evidence to suggest that rapacious hunting practice of the paleohunters in North and South America 12,000 years ago may have caused…The demise of the very animals they hunted" (Powell 1987). The evidence Powell suggests is that the extinction of a large mammal is usually followed by the appearance of humans in the fossil record. This coincidence is not only seen in the fossil records of North and South America but Europe and Asia as well. Powell shows that as human populations increased local extinctions of large mammals occurred. This was probably due to the fact that there were not many predators that could hunt the large mammals except man. For this reason it is also highly like likely that man and large mammals did not co-evolve which ultimately resulted in the extinction of large mammals.
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...
Bison have been around for 10,000 years. Their ancestors where known as giant bison and they were hunted by the paleoindians that came over on the Bering Strait. The giant bison however became extinct because the paleoindians hunted them and at the end of the last ice age, most of the vegetation they fed off of was destroyed. Dwarf bison, the bison that are around today, survived the ice age because the dwarf bison were faster, reproduced more rapidly and required less vegetation to sustain them. The destruction of giant bison resembles what happened to the bison in modern day America; accept they had to survive droughts instead of extreme cold.
That “prehistoric” whales had the jaw of a wolf (a fifty million year old wolf to be exact) and the ear of a whale. I think that all of our semiaquatic mammals play a big part in the evolution of land mammals to water mammals. Like at some point of say an otter’s life, nature told it to stop evolving so that it wouldn’t become completely marine, but semiaquatic as we named it. How did it know when to stop evolving? Was it changes in the environment? Or the need for survival? Which brings around another question, how did we go from a planet of just rock and magma, to a planet thriving with
A whole lot of hypotheses have been used to explain the quick expansion of animal species in the early Cambrian period about from about 541.0 million to about 485.4 million years ago. The most modern explanations for the Cambrian explosion takes pieces of a lot of these hypotheses and melds them together; incorporating genetic, ecologic, abiotic conditions that set the evolutionary wheel in motion. The current state of understanding the Cambrian explosion still remains a topic of open and exciting debate. The processes in the hypotheses can be stand-alone or very tightly interconnected and mutually supporting of another. One can say the complexity of modern Animalia can be attributed to the complexity of the processes that happened during the rapid diversification attributed from an interaction of biotic and abiotic processes in the Cambrian period.
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.
Did you know that more than 90 percent of all organisms that have ever lived on Earth are extinct? According to Pandey, the author of Humans Pushing Marine Life toward ‘Major Extinction’, nearly 10,000 species go extinct each year, and this rate is estimated to be 1,000 times higher than the natural extinction rate (1). Human beings are causing irreversible damage to the oceans and their wildlife, which is being led by two major reasons: Commercial fishing or over-fishing, which damaged the marine environment and caused a loss in the marine life diversity, and pollution, which is a primary way of the extinction causes that drastically modifies the marine life habitat. As a result of the commercial fishing and pollution, many of the marine species will start disappearing of the oceans. Briggs emphasizes that over-fishing “has induced population collapses in many species. So instead of having less than a hundred species at risk, as was the case some 30-40 years ago, there are now a thousand or more (10).”