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Cretaceous paleogene extinction debate
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Cretaceous Extinction Event
Causes, Evidence, and Effects on Biodiversity
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...
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...asted about a million years. The eruption was not violent compared to others, but it was able to send ash as high as the stratosphere. So another theory is that shifting of the tectonic plates caused the Deccan Traps to erupt, causing the release of massive amounts of carbon dioxide out of the earths crust. This went on to create a global greenhouse effect that cooked the planet. This along with climate change from continental drift could have caused the K-T event. Paleontologist Richard Cowen believes the evidence of an asteroid impact is so strong that there is no point to explain that evidence as solely volcanic effects. We should concentrate on the fact that the K-T boundary coincided with two different, yet very dramatic events.
Works Cited
Cowen, Richard. A History of Life. 2nd ed. Vol. 1. Massachusetts: Cambridge, 1999. Print.
On May 22, 1915, an explosive eruption at Lassen Peak devastated nearby areas and rained volcanic ash farther 200 miles to the east! This explosion was the most powerful in a series of eruptions from 1914 through 1917. ...
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...
However, there are still many factors in the evidence collecting process that make it difficult to determine the actual events, let alone the sequence of them. For instance, at the end of the Permian, giant volcanic eruptions occurred in Siberia, spewing out some 2 million km3 of basalt lava, and covering 1.6 million km2 of eastern Russia to a depth of 400-3000mteres, equivalent to the area of the European Community. Consequently, with increasingly precise dating, the Siberian “Trap” (areas which are composed of basalt, a dark-colored igneous rock which is generally not erupted explosively from classic conical volcanoes, but usually emerges more slowly from the long fissures in the ground) have switched from having only a minor role in the Permian crisis to being the most probable cause of the whole catastrophe. Some scientists have even suggested recently that the massive flood basalts were actually themselves caused by a giant extraterrestrial impact, which tore deep into the continental crust of that part of present-day Siberia. So this is yet another example the evolutionary and
The New World, in the minds and descriptions of European explorers and settlers during the sixteenth century, was comparable to a paradise on earth. The landscape was so vast and indescribably beautiful that even Columbus had trouble articulating its splendor. However, lacking a consciousness of conservation, Europeans felt little remorse in exploiting the land and subjugating its people. From the beginning Europeans set out to transform as much of the New World into the Old World as possible. As a result, the New World, over the course of two centuries, was overtaken by foreign plant and animal species, leveled by deforestation, and devastated by disease. This imposition of Old World values significantly impacted the ecology of the New World.
From modern examples and records we know that volcanic activity can set of a chai...
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...
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.
seems like it happened so sudden, as geologic time goes, that almost all the dinosaurs
Geological and paleontological laymen may have difficulties grasping more complex theories, but Gould’s work provides a fresh, vernacular insight into extinction hypotheses. Although two of the three theories are utterly absurd, according to Gould, reading something an average reader can understand and be entertained by thoroughly is refreshing. “Sex, Drugs, Disasters, and the Extinction of Dinosaurs” is not an average expository, scientific research essay. The writing provides necessary perception to the reader composed of facts, professional opinions, and tested hypotheses. An American phenomenon such as “sex, drugs, and rock & roll” was incorporated into scientific concepts to form a compelling, analytical piece of rejuvenating writing. The topics themselves were paired with excellent syntax and bizarre, yet entertaining, sideline quips. Such an enlightening tale of research should be enjoyed by the mass
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.
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
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...
It is the year 4076. The Earth is being taken over by dinosaurs. Then there are four friends the know each other and need to get out. The only place to go is a different planet in outer space. So what will they do?
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