K-T Boundary Research Papers

“A minority disputes this theory, arguing that other events-such as volcanic eruptions, sea-level changes or a series of impacts-were to blame for the spectacular loss of species that occurred at the transition between the Cretaceous and Tertiary periods…”

He noticed that the rocks at the top of the section had a very high percentage of fossils of living mollusc species. Those at the bottom of the section had very few living forms. He deduced that this difference was because of the extinction of older forms and the evolution of living forms during the time that the rocks were being deposited. He divided the Tertiary rocks into three sub-ages: the Pliocene, the Miocene, and the Eocene. 90% of the fossil molluscs in Pliocene rocks were living today. In the Miocene rocks, only 18% of the molluscs were of living species, and in Eocene rocks, only 9.5%.” (Polly et al.,

The scientists believe that the herbivores ran out of plants, and trees and so all of the herbivores died and after all of the herbivores died, all of the Carnivores died as well. Another theory is that a big asteroid hit the Earth, and the asteroid caused a global extinction.. The final theory that the scientists thought of happening was a disease. Disease may of happened from one dinosaur getting sick and then it just passed on from dinosaur to dinosaur.

Gerta Keller, professor of geosciences at Princeton University, has recently conducted research on the Chicxulub asteroid in which she analyzed new core samples taken from the asteroid site (Botzer 2004). These samples indicate that the impact that occurred at Chicxulub actually predated the mass extinction of the dinosaurs, which occurred at the Cretaceous-Tertiary boundary about sixty-five million years ago. Keller claims that the Chicxulub impact occurred approximately 300,000 years before the extinction (Keller 2004). Although previous researchers estimated that the Chicxulub asteroid was the cause of the extinctions, there had always been doubts about the exact age and size of the crater, and about the origin of the “mega tsunami deposits” that were located within the crater (Keller 2004). The focus of Keller’s recent research was on finding some answers to these questions. To do so she analyzed Cretaceous limestone, dolomite, and anhydrite deposits as the site of the Chicxulub crater (Keller 2004).

It is difficult to envision that one of the greatest impact craters on Earth that measures up to 180km wide and 900m deep could just vanish just from sight. There have been many different dinosaur extinction theories offered in the recent decades. These range from poisonous plants to mass suicide by dinosaur herds. Although one concept as to how the dinosaurs became extinct has gained a wide acceptance since the 1980’s, involving a major earth impact by a meteor or comet (Icr.org, 2014). This horrific catastrophic event is thought to have extinguished up to two thirds of all animal and plant species, leaving behind a large crater found in Chicxulub, Mexico (LiveScience.com, 2014).

In Stephen Jay Gould’s “Sex, Drugs, Disasters, and the Extinction of Dinosaurs”, Gould investigates three possible theories hypothesizing the reason behind the extinction of dinosaurs. The first theory suggests that dinosaurs became extinct due to a rise in temperature, which caused sperm to die, leading to the sterilization of male dinosaurs. The second hypothesis offer that many dinosaurs consumed bitter plants that contained psychoactive agents which their lives could not detoxify out of their systems. The last speculation about the dinosaur’s extinction is that a large cloud of dust formed in the atmosphere after an asteroid hit Earth’s surface. This dust cloud blocked out the sunlight, causing temperatures to drop and made photosynthesis impossible. Gould uses these three theories to lead to his central claim that science isn’t just about making fascinating claims, but should have a well developed hypothesis.

They chose the time period of 375 million year old rocks because they thought that it was an ideal age to check the transition. They were only able to find fish found in 380 million year old rock and the animals with limbs in 365 million year old rocks. Sedimentary rocks are ideal because they are made due to the turns of the river, ocean and lakes. This is the place where fishes and animals are ideal to live and survive upon. Also the environment, in which they are made, doesn’t destroy the fossils and they preserve them. In 2004, the fossils were found on Ellesmere Island in Northern Canada. This location was chosen because this is the place where there are no humans or roads or any disturbance that would forbid them to dig anywhere they want.

There was much speculation regarding the K/T boundary being caused by a meteorite. The impact of this event was believed to have led to extended volcanic activity periods that in turn further polluted the atmosphere. The impact of the K-T boundary happened to be attributed to the extinction of dinosaurs that might have been as a result of new diseases. The impact affected all living things including primates. The impact is believed to have drastically slowed primate evolution (Clyde, 2010).

According to Gould essay, the theory of disasters is “a large comet or asteroid struck the Earth some 65 million years ago, lofting a cloud of dust into the sky and blocking sunlight, thereby suppressing photosynthesis and so drastically lowering world temperatures that dinosaurs and hosts of other creatures became extinct.’(50).The theory of disasters proves worthy of more research when compared to the theory of sex and drugs. This is because the disasters theory “generates tests, provides us with things to do, and expands outward” (55). Cowell’s hypothesis (the theory of sex) “has generated nothing for 35 years” because scientists can do nothing with it and the theory of drugs “will win a few press nots and fade into oblivion (54-55). Although talking about asteroids, dust and darkness is no more entertaining than talking about fried testicles or terminal trips “it’s the iridium – the source of testable evidence – that counts and forges the crucial distinction between speculation and science.”(55).The iridium bridges the gap between science and speculation because it is a source of testable evidence. The iridium is testable because geologist determined when high iridium first formed and related it to the comet that struck the Earth. Therefore, the theory of disaster is the most superior evidence for dinosaur extinction when compared to the method of sex and drugs due to its abundant

The impact was so strong that it caused the extinction of dinosaurs and many plants. We learn about extinction as children and understand that those are animals that roamed the Earth a long time ago but no longer exist. Ancient authors like Aristotle were not familiar with extinction. They believe that once an animal or plant was here it was here for good. This changed in the 18th century with French

The extinction of the dinosaurs, absolutely a thrilling topic. In Steven Gould’s persuasive article he goes into great detail to describe the nature of science and it’s profound nature to help us in the pursuit of knowledge when used correctly. He then begins to describe three scenarios in which could’ve led to the extinction of the dinosaurs in which two while seemingly plausible at first glance are in actuality simply speculation. Thus, just like a good hypothesis using evidence to support his critiques and support of the hypotheses. Which is why I agree with Gould’s statement on how out of the three hypotheses, the extinction of the dinosaurs

The KT extinction asteroid impact, arguably the most recognizable asteroid impact ever known, also known as the “Chicxulub Asteroid Impact” from the name of the location the impact occurred.(Schulte et al., 2010) The event itself happened around 65.5 million years ago. It is widely accepted as the event that caused the mass extinction that marked the boundary

Then the movie focused on the question what did really happen to the dinosaurs? Sixty five million years ago, a six mile wide asteroid hurtling through space at 15 kilometers per second slammed into what is now Mexico's Yucatan Peninsula at a site known as Chicxulub. The impact had left a crater 110 to 170 miles in diameter buried nearly a kilometer underground and sparked massive volumes of ash into Earth's atmosphere. This impact is believed to end the existence of the dinosaur and paved the way for the rise of mammals and other species which is now in existence. Scientists have identified 139 impact craters scattered over the surface of the Earth as a result of the main impact. The collision was so catastrophic and enriched dust high into the atmosphere, shutting off sunlight for weeks or months and cooling the planet. Acid rain and wildfires also followed the collision, many plants died, as did many of the animals that ate them including the dinosaurs.

Ever since the history of Earth has been studied using fossil records, extinctions have always been the object of fascination and interest, particularly the mass extinctions that occurred throughout Earth's history. A mass extinction can be caused by disruptive global environmental changes, where large numbers of species have become extinct (Urry et al. 2008). There have been five major extinctions documented based on fossil records over the past 500 million years, but the Cretaceous (KT boundary extinction – a name that meant it began the Tertiary era) extinction caught a lot of

These techniques led to the discovery of the boundary between the two eras. A single thin layer of clay found within predominantly limestone rocks established this. By comparing the marine life found in, above, and below the clay, the marine life, like the dinosaurs, had been terribly affected by the extinction event. The percentage of life in the upper layers was dramatically lower than that in the lower. This was far more compelling than what was suggested by dinosaur’s fossils.