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Essay Example: Dinosaur Extinction

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991 words
Wesleyan University
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The extinction of dinosaurs has been widely discussed by scholars and scientists, to find out the extinction factors, and how the process unraveled. Scientific evidence portrays dinosaurs as a unique species of mammals that inhabited the earth during millions of years ago. Though science has established that the mammals existed on the planet, it has not given a definite answer to the extinction question. The theories seeking to explain the extinction of the dinosaurs can be classified into two categories; the intrinsic based factors, and the extrinsic based factors (Archibal 213-224). The first category involves the factors based on the earths natural processes that may have taken a long period to manifest and cause harm. The other category sums up the external factors that lay claim to extra-terrestrial catastrophes that may have caused sudden destruction. The presence of diverse factors has prompted scientists to dig deeper into finding evidence. However, each factor is supported by certain evidence that is overwhelming in its way. Having studied the different factors. Some scientists have proposed that the factors may have collectively caused the extinction rather than separately. This essay seeks to understand the most overwhelming of the theories and the evidential basis that makes it valid

Extra- Terrestrial Theory

According to Walter and Luis Alvarez, an extraterrestrial body that fell on the earth precipitated the extinction in the late Cretaceous period. The extra-terrestrial impact theory advanced by the two scientists propounds that the massive body hit the earth with incredible impact. The impact on the ground resulted in the earths crust being thrown into the atmosphere. The dust that ensued blocked the solar radiation hence rapidly diminishing the earths temperatures (Brusatte 628-642). The low temperatures caused by the blockade disrupted the photosynthetic processes in the sea and land. Subsequently, green plants and ocean planktons diminished.

The massive dust blown into the earths atmosphere caused a great variation in the gaseous proportions in the atmosphere. The theory suggests that the dinosaurs may have suffocated due to insufficient oxygen. The carbon dioxide accessible to plants diminished because of the dust. The plant-eating dinosaurs thus couldnt survive with the absence of plants to feed on. The meat-eating dinosaurs were affected by the disruption of the food chain, later leading to their extinction (Brusatte R415-R417). After a while, it is alleged, the dust levels reduced hence trapping terrestrial radiation from the earth. The dust thus caused a greenhouse effect on the earth. A greenhouse effect causes the temperatures to rapidly increase because of the terrestrial radiation.

Another dime of the hypotheses suggests that due to the temperatures occasioned by the collision, nitrogen gas thus reacted with oxygen, and later with vapor, causing dangerous acid rain on the earth. Besides, the atmospheric gaseous imbalance may have further caused suffocation upon the dinosaurs living on the earth at the time. Acid rains destructive impact extends not just to destroying vegetation but also to contamination of water resources that the animals obtained water.


The basis of the extra-terrestrial impact theory is the evidence of iridium deposits that have been found in different parts of the earth. Iridium is an element that is a component of asteroids, meteors, and comets. When an extra-terrestrial body hits the earth, the element iridium is normally deposited at the impact point and beyond. Geologists have discovered a consistent layer of iridium on different places on the earth that denote a massive body may have hit the earth and spread the element over the earth due to the impact (Stephen 8). The fact that the iridium elements spread evenly over a huge area of the earth suggests the incredible size of the asteroid hence substantiating the massive impact and effect left behind.

Quartz grains have been geologically identified as belonging to the late Cretaceous period. The evidence of the quartz grains adds more evidence to the theory of a massive extra-terrestrial body having hit the earth. Quartz grain result when granite rock is exposed to incredible heat and pressure that causes the rock metamorphosis. The vast and widespread quartz rocks and pieces found in the various spots on the earth that indicate their existence to around the period when the iridium layers were deposited corroborates the theory.


The geological analysis may not be 100% accurate to create certainty. Scientists often make errors and misinterpretation of facts and evidence. The fact that the alleged extinction occurred 65 million years ago, presents a huge challenge in establishing accurate forensic facts as to dates, and exact physical location. Some of the evidence have been corrugated by the earth's continuous processes that bring more confusion. The fact that scientists depend on the study of geology mainly to establish the extra-terrestrial impact theorys evidence considered together with the arduous task of accuracy invites the scholars to apply the more probable than not approach, hence absolving errors and misinterpretations of scientific data in the process. The downside is that a slight mistake may be neglected but could be the disapproving factor of a whole theory.


The extraterrestrial theory establishes an overwhelming hypothesis as to the extinction of dinosaurs. Through the rational and reasonable turn of events that began when the alleged asteroid made collision on the earth, it is clear that the theory has a basis to be trusted as a true cause. The evidence of the iridium layers is the major evidence and having been verified and approved by geological organizations remains as the primary tangible evidence of the massive asteroid that devastated the earth. The quartz rocks precipitated by the heat and pressure factors come in handy to support the theory.


Works Cited

Archibald, J. David. "What the dinosaur record says about extinction scenarios." Geological Society of America Special Papers 505 (2014): 213-224.

Brusatte, Stephen L., et al. "The extinction of the dinosaurs." Biological Reviews 90.2 (2015): 628-642.

Brusatte, Stephen L. "Evolution: How Some Birds Survived When All Other Dinosaurs Died." Current Biology 26.10 (2016): R415-R417.

Stephen, Peter. "Dinosaur Extinction." Scientific American 313.3 (2015): 8-8.


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