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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inhabit the ocean now was bacteria. With the fossil record we conclude that towards the middle of the Devonian Period there were fish with actual bones, gills, and teeth. Also thanks to the fossil record we have found the ancestor for most modern fish which was alive and well in the Devonian period which was the Ray-finned fish. There was also extensive reef growth during this time, mostly around Gondwana (supercontinent that occupied most of Riley 7 the southern hemisphere). During the later part of the period sharks and rays were common. Also there were surprisingly new advances in plants at this time with the colonizing of the land by plants, they continued to evolve during the period. The growth of Earth’s first forests, of course forests then were very different than the forests that are ubiquitous today. The forests in the Devonian Period consisted of mostly ferns and Lycophytes. However they did grow to gargantuan sizes that which makes modern ferns pale in comparison. By the end of this period Earth had seen its first trees which were Archaeopteris. These trees could grow to heights that would exceed 98 feet. At this time there was an Organism that would give rise to the amphibians and fish, this creature was named Tiktaalik rosae. “Tiktaalik was an aquatic organism that could walk on the bottom it had fish-like pelvis however its posterior limbs were larger and stronger. It also had a head that resembles a crocodile, and nostrils which made it capable of breathing air.”-”Devonian”. It was only about 58 million years after this period in which the first reptiles and true amphibians were around. Amphibians had evolved earlier than the reptiles though due to their soft moist skin they were still dependant on water for survival, the sun would leave them dehydrated, most of their bodily water was used to coat their skin. Some grew to sizes about 15 ft. long like the Eogyrinus (Interestingly, the skin of Eogyrinus was scaly rather than moist, evidence that the earliest amphibians needed to protect themselves from dehydration.) -Prehistoric Riley 8 Amphibians. The first reptiles had a huge advantage over the amphibians, that was the scaly skin which allowed them to retain their bodily water when exposed to the Sun. This new feature granted them the ability to survive on land for an extended amount of time, since they now did not have to rely on the water as a source of sanctuary now. Also producing hard shelled eggs was a new trait which gave the reptiles the ability to reproduce away from the main body of water and then their offspring could eventually explore more, and more land. Nearing this time was the most tremendous event that caused 96% of all species on the Earth to die off. This extinction is called the Permian mass extinction. “All live that lives today is descendant for the surviving 4%. Many possible causes are considered for this event however it is unclear which one is the culprit.”-”Big five Mass extinctions” Approximately 230 million years ago reptiles first evolved into dinosaurs, of course this evolution like all evolution did not occur instantaneously, over night, or through one generation. It was a gradual process where the reptiles gradually became naturally selected based on the genetic benefits. However the common ancestor between the Dinosaurs and Reptiles is the archosaurs. While one lineage of the archosaurs can be traced to the dinosaurs and birds the other side of the linage leads to the crocodile and his relatives. This diverge in the evolutionary tree occurred at approximately 220 million years ago. So it is safe to say Archosaurs played a very Riley 9 important role in history. Early members of the Archosaurs clade took over the large vacant areas left after from the death of most the herbivores and carnivores that died by the end of the Permian. “Early mammals such as the carnivore Proterosuchus (about 1m long) had a sprawling walk (that closely resembles modern lizards). Some archosaurs such as Vjushkovia and Erythrosuchus were large carnivorous creatures (up to 5m long), it fed on other large plant-eating reptiles” -EVOLUTION OF THE ARCHOSAURS. About 200 million years ago the Triassic-Jurassic extinction occurred which resulted in mostly marine and animal deaths. Possible causes of this are vague but multiple options are being considered. Mammals (which are characterized by the female producing milk in the mammary glands, all of them are warm blooded which means they have endothermic metabolisms) had evolved during the time of the dinosaurs.
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
event Riley 10 caused a nuclear winter which is characterized by the blocking of the sun by dust particles in the atmosphere,which caused the death of most vegetation available to all species since this vegetation was the primary food source for the herbivores most of them died, resulting in a cause and effect scenario where the carnivores that preyed on the herbivores also perished. Early mammals were small allowing them to survive on little food, outlasting both the nuclear winter and the dinosaurs. After the reign of the dinosaurs mammals were left left to dominate the land. They roamed all available land inhabiting all of it and adapting to fit their environment. Interestingly enough some of the modern mammals resemble dinosaurs. One example is the giraffe which closely resembles the Brachiosaurus. One of the questions people ask most often when evolution is brought up is ‘how did humans evolve then’. We can trace our human lineage to approximately 6 million years ago, where a species gave rise to the hominid lineage and the chimpanzees lineage. This occurrence took place in Africa, where we have the earliest fossils of hominid species. First known hominid to deviate from the predecessor species was Australopithecus anamensis which lived in is now Kenya, and on its hind legs. This is known as bipedalism. Which gives early hominids an advantage over the early chimpanzees and other apes. For when apes and chimpanzees move around they can only walk on two legs for a short amount of time. Reasoning behind this is that they
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
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
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...
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 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...
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.
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.
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...
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.
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)
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...
Among the species that perished were the dinosaurs, pterosaurs, belemnoids, many species of plants, except ferns and seed-producing plants, ammonoids, marine reptiles and rudist bivalves. Severely affected organisms included planktic foraminifera, calcareous nannnoplankton, diatoms, dinoflagellates, brachiopods, mollusca, echinoids and fish. Mammals, birds, turtles, crocodiles, lizards, snakes and amphibians fared much better and were mostly unaffected by the End-Cretaceous mass extinction (“The End-cretaceous (K-T) Extinction”, accessed 2000...
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).”