The Asteroid Impact Theory on the Great Dying - Coursework Example

The Asteroid Impact Theory on the “Great Dying” The age of the dinosaurs, and the mammoth creatures themselves, have always been a source of fascination for many. But before dinosaur bones were found alluding to their previous existence, they were but myths—giant creatures that fairy tales were made of. However, it was proven that indeed, these colossal animals did roam the earth millions of years ago. It was said that the first dinosaur fossils were found through an expedition of a French Canadians and Indians in the Ohio River in 1739 (Mayor 1). The bones were brought to France where it was presented to King Louis XV (Mayor 2). And after several years, the find became the first dinosaur fossils to be studied by scientists (Mayor 2). With the reality that dinosaurs lived and walked the earth sixty-five million years ago, as presented and proven by modern studies until the present time, the question of why they became extinct plagued many scientists. However, even with the help of modern technology, there have not been a theory proposed that is deemed an accurate and true explanation of the reason for “The Great Dying” by the whole of the scientific world; “the identity of the dragonkiller is still unknown” (Hanlon 19). Nevertheless, there is a wide array of theories that, while not concrete enough to be accepted as the theory of the extinction of dinosaurs, have merit. The Asteroid Impact Theory of Luis and Walter Alvarez in 1980—which is like the opposite of the Big Bang Theory—is one of the evolving and most popular and strongly supported theories of “The Great Dying” (Smith and Hutchinson). This paper will discuss this theory in detail and how it answers the many questions and incidents pertaining to the extinction of the dinosaurs. Before delving into the Asteroid Impact Theory, it is best to illustrate the two kinds of theories available for the explanation of the extinction of the dinosaurs. The Two Types of Theories There are two kinds of theorists when it comes to explaining the reason for the extinction of the dinosaurs during the Cretaceous period—the extrinsic catastrophists and the intrinsic gradualists (Smith and Hutchinson). While the former suggests that the mass extinction that happened at the K/T Boundary was due to natural and earthly conditions (intrinsic) and spanned a long time before the culmination that brought about the extinction, the latter believes that the extinction was “extrinsic, meaning of an extraterrestrial nature, and catastrophic, meaning fairly sudden and punctuated” (Smith and Hutchinson). Examples of intrinsic gradualist theories are the Volcanism and The Theory of Plate Tectonics, while The Asteroid Impact Theory is extrinsic catastrophist in nature (Smith and Hutchinson). While intrinsic gradualists reject The Asteroid Impact Theory, it still remains as the most widely accepted theory regarding the extinction of the dinosaurs. The Asteroid Impact Theory The catastrophic theory, which resurfaced in 1980, was proposed by father and son Luis and Walter Alvarez, together with nuclear chemists Frank Asaro and Helen Michel in Science through an article entitled “Extraterrestrial Cause for the Cretaceous-Tertiary Extinction” (Archibald 13). The theory states that the extinction of the dinosaurs was brought about by the impact of an extraterrestrial object—an asteroid—which caused a vast explosion in the Gulf of Mexico, now the Yucatan Peninsula, equal to that of a billion thermonuclear bombs (Hanlon 15). In an instant, every life form within a 300 mile radius were reduced to ashes (Hanlon 15). The asteroid impact also brought about severe climactic changes that the dinosaurs were not able to adapt to. Chronologically, this is what happened, as clearly elucidated by Michael Hanlon (15) for The Daily Mail: The colossal impact of the asteroid would have thrown trillions of tons of rock and dust into the atmosphere. In a few weeks, the skies all around the planet would have darkened. Our world would have entered a long night that lasted maybe a decade - the winter to end all winters. With little or no sunlight hitting the Earths surface, virtually all the green vegetation would have perished, unable to photosynthesise the sugars needed by plants to live. And with no plants, the herbivorous animals would, in turn, have died. And when they died, the carnivorous animals which ate them would have perished as well. The great lizards were gone (along with 50 per cent of all species) and the Earth took millennia to recover. It was the descendants of the furry creatures which had scurried around the dinosaurs feet, and which somehow survived the catastrophe, that took their turn at the top table. The asteroid impact set in motion a series of events (stated above) that ultimately lead to the “The Great Dying” and encompasses a lot of other theories, including mutation, climate changes, the ice age, and even poisonous gases and volcanism—as the impact was huge enough to trigger earthquakes, tsunamis, typhoons, acid rain, and volcanic eruptions (“The Alvarez Asteroid Theory”). These events then resulted to the lack of food supply and diseases that resulted to the deaths of the dinosaurs who survived the impact (as shown in the diagram below). Although the term “instantaneous” is used by Alvarez, it does not mean that it happened in an instant because for geologists, an instant may mean decades or even a century (Alvarez cited in Archibald 14). (c)1997, 1998, 1999 The Dinosaur Interplanetary Gazette Of course, this theory of sudden death was not concocted out of mere musings. There are numerous proofs that lead Alvarez and his team to believe that the impact of an asteroid or a comet on the earth’s surface caused the wave that brought about the extinction of more than 50% of all life forms, including all of the dinosaurs. Proofs The Iridium Layer. The main basis that the Alvarez team had to get to the conclusion of the Asteroid Impact Theory was the layer of sedimentary rock they analyzed and found to be high in Iridium content at the K/T Boundary all over the world, which dates back 65 million years ago—around the time that the dinosaurs ceased to exist (Archibald 43 and Wigmore 19). “Asteroids and similar extraterrestrial bodies are higher in iridium content than the Earths crust,” so the Alvarez team then concluded that since there could be no other source (like volcanic activities) for the high concentration of Iridium but the fact that it is “composed of the dust from the vaporized meteor” (Smith and Hutchinson). Crystals and Molten Rock. The discovery of spherules (“solidified droplets of molten rock possibly injected into the atmosphere by an impact”) and shocked quartz (“when quartz is subjected to very rapid pressure and temperature increases”) in different parts of the world further strengthened the hypothesis that there indeed was a massive explosion brought about by a tremendous impact from an immense extraterrestrial object (Archibald 131). Although some of the samples were rejected as mere fossil algae or insect eggs, many have been authenticated and due to the fact that these specimens were scattered all over the world, it is logical to think that a massive explosion congruent with the Asteroid Impact Theory was the reason (Archibald 131). “Kenneth Miller has discovered a two-inch layer of glass beads in the K-T layer near the Bass River in New Jersey, USA, supporting Alvarez theory” (“The Alvarez Asteroid Theory”). The Yucatan Crater. Although at first, the Alvarez team was not able to find a crater that would fit the description of the asteroid impact, they later on found their crater at the Chicxulub, on the Yucatan Peninsula of Mexico (Archibald 132). The Yucatan crater is “a 120-mile-wide (180 km), 1-mile-deep (1600 m) impact crater” which was dated as 64.98 million years old by the group headed by Carl Swisher (Smith and Hutchinson and Archibald 132). The specifics of the Yucatan crater made it the best candidate for the site of the asteroid impact that killed the dinosaurs into extinction. There have been other huge craters reported that also corresponds with the time period of the end of the age of the dinosaurs, like the Shiva crater located under the Arabian Sea off the coast of India near Bombay, but it can be concluded that they were just parts of the same bolide or asteroid (“The Alvarez Asteroid Theory”). Fossil Record. Everyone has agreed that the dinosaurs became extinct 65 million years ago. And the fossil record alludes to a catastrophic event like the asteroid impact proposed by the Alvarez team. This is because “paleontologists sifting through the Earths layers say one minute you see their fossils, the next they are gone” (Wigmore 19). The dates of the fossil records prove that it was not a gradual event that lead to the extinction of the dinosaurs, but rather a ctatrophic one. Again, this strengthens Alvarez’s theory of sudden extinction. The dinosaurs, 65 million years ago, just died unexpectedly and abruptly. Conclusion Although there have been many anomalies that were found in Alvarez’s theory, like the Iridium spike in 95 sites that Walter Alvarez later on admitted (W. Alvarez cited in Archibald 130), his theory is still the most logical and plausible for it explains all the specifics that the other theorists focused on. It is logical and it is laden with physical proofs. Every single event that leads to the sudden extinction of the dinosaurs is explained by the Asteroid Impact Theory. With one main and extreme occurrence (the asteroid impact), there resulted several events (volcanic eruptions, ice age, acid rain, etc.), and these events lead to calamities and a disruption of the normalcy of life (diminished food supply, diseases, etc.). All of these combined, with the initial point and ultimate source being the asteroid impact, resulted to the abrupt extinction of the dinosaurs. And although there is still no universal theory for “The Great Dying,” The Asteroid Impact Theory is the most widely known and accepted because it is the one with most merit and proofs. The fact still remains that what happened to the mammoth creatures was definitely huge enough to eliminate what are deemed as “the most successful and adaptable group of large animals ever to have lived” from the face of the Earth (Hanlon 15). Works Cited Archibald, J. David. Dinosaur Extinction and the End of an Era: What the Fossils Say. New York: Columbia University press, 1996. Hanlon, Michael. “So Did an Asteroid Kill off the Dinosaurs?” The Daily Mail 2 February 2006: 15. Mayor, Adrienne. Fossil Legends of the First Americans. Princeton, New Jersey: Princeton University Press, 2005. Smith, Dave and Hutchinson, John. What Killed The Dinosaurs?: Extinction Theories. 28 September 2005. DinoBuzz. 27 March 2007 . “The Avarez Asteoid Impact Theory.” 2007. Enchanted Learning. 27 March 2007 . The Dinosaur Interplanetary Gazette. Dinosaur Extinction: Whered those big guys go? Was it a Meteor? Climate Change? Closing of the neighborhood 7-11? or What? 15 April 2001. 27 March 2007 . Wigmore, Barry. “Case Closed: An Asteroid Did Do for the Dinosaurs.” The Daily Mail 6 December 2006: 19. Read More