Essay about Examining the Cretaceous: Paleogene Extinction Event

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

8. The periods in which there were mass extinctions are Permian – volcanic eruptions which spewed lava and put CO2 into the air which warmed the climate an estimated 6 degrees Celsius. The resulting of oxygen deficiency. And Cretaceous – asteroid or comet

Dinosaurs ruled the earth for over 65 million years and thankfully for the human race, they became extinct. Ultimately, only a major catastrophe could completely wipe out an entire species, let alone an entity of dinosaurs and the debacle on the causes of dinosaur extinction have flooded the minds of paleontologists for centuries. Geologist and zoologist Stephen Jay Gould published “Sex, Drugs, Disasters, and the Extinction of Dinosaurs,” to compare scientific and speculative causes of dinosaur decimation. Personally, I found this passage very informational and enjoyed reading it. Gould provides three theories that capture the reader’s curiosity, allowing room for pondering in one’s mind.

The End Cretaceous impact hypothesis states that an asteroid impact on the earth caused the extinction. The evidence that supports this hypothesis include the crater found in the Yucatan Peninsula, the rare metal Iridium, and fractured “shocked quartz” crystals that have been shown to cause high-energy explosions. The End Cretaceous flood volcanism hypothesis states that a giant volcano eruption, or a series of volcano eruptions caused the extinction The evidence that supports this hypothesis includes immense lava flow, and volcano explosions, which happen to exposed iridium.

Large amounts of iridium – a chemical element that is not a part of the Earth’s crust composition – were originally found in rocks of Europe and United States, and have been found everywhere ever since. Iridium, common in meteorites, is a testable evidence of the disaster hypothesis. Gould continues that the Cretaceous debacle, which is one of five episodes of mass dying, occurred at the same time as the large comet might have smashed into the Earth. The author believes this is not merely a coincidence, rather, it is a proof of the cause-effect relationship. The demise of a wide range of habitats along with the extinction of dinosaurs gives an inestimable advantage to the disaster theory over other claims, the author adds. The comet struck the Earth, and habitats, from terrestrial to marine, died with geological suddenness. Finally, this hypothesis has had an impact on the study of an atomic war and its consequences. A nuclear war, Gould says, may cause a huge drop in temperatures and result in the extinction of humanity. Testable evidence, study, development, contribution – all this makes good science.

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.

The Cretaceous-Tertiary extinction, also known as the K-T extinction, was a global extinction event that struck the Yucatan Peninsula at the end of the end of the Mesozoic Era, 65 million years ago. Walter Alvarez first discovered a meteorite big enough to be called a small asteroid that hit the Earth, creating the Chicxulub crater. Once the asteroid struck the North American continent, there were igneous rocks underneath the crater that contained high levels of a rare siderophile element, iridium. This catrostopic event had a massive effect on the environment, as several mammals, birds, and plants became extinct. It also caused an impact winter that made it impossible for plants and plankton to photosynthesis, as 75% of inland animals and 90% of marine species were affected. Not only did it cause an impact winter, but the asteroid also caused volcanic eruptions, climate change and sea level rise. Geologists have also found rich dinosaur, plant and marine fossils to illustrate the K-T extinction. This event not only caused species to become extinct, but it also had an adaptive radiation, as other species were able to diversify.

When visiting museums such as the American Museum of Natural History in New York City we can get a first-hand look at some of the massive creatures like the wooly mammoth that used to roam our planet some 11,000 years ago. And after viewing the skeletons of such extraordinary creatures known as the megafauna we may ponder as to what event transpired to eliminate so many species. What we do know is the late Pleistocene era marked a time of fluctuating climate that coincided with the migration of people into the New World. During this period mammals such as the woolly mammoth and mastodons were becoming extinct. However, questions still remain to determine if it was because of severe climatic change, or possibly the extinctions occurred from over-hunting by humans, or possibly a combination of both? These are many of the concerns that have created the foundation for a serious debate among many scholars in the anthropology and archaeology community.

The K-T event, or the Cretaceous-Tertiary extinction event, is the name given for the vanishing of the dinosaurs and different species that took place about 65 million year back. For ages, scientists believed that this event was caused due to the atmospheric and topographical changes that invaded on the dinosaurs’ food supply. But, in the 1980s, researchers Luis and Walter Alvarez discovered a layer of iridium on the earth’s surface. It suggests that a comet, space rock or meteor effect might have caused the extinction of the dinosaurs. In the 1990s, researchers found the enormous Chicxulub Crater at the tip of Mexico’s Yucantan Peninsula, which dates to the period being referred [1].

So what killed the dinosaurs? Without having any background education in science it is hard for the general public to comprehend such matters and they rely on the knowledge of the scientists in this field. Although there has been much research on the subject nobody has come up with a conclusive answer. And we are left to read the countless articles, all having their own opinions as to the mass extinction. One such theory is that a shift in the solar system could have caused the mass destruction. According to an article published in Nature magazine,

How exactly the asteroid damaged the Earth remains unclear, but the power released by such an impact is unquestionable. Effects possibly include reduced sunlight over a period of several months which possibly led to the decline or even total halt of primary production (via photosynthesis). One of the dominant signatures of the extinction at the KT boundary was the low activity of primary production, the possibility of reduced sunlight is high (Schulte et al. 2010) . Even if the primary production proved to be on a decline when this impact occurred, there is still some uncertainties as to where exactly the impact hit. This was why asymmetries in subsurface features of the Chicxulub crater were observed via geophysical methods were analyzed and it was calculated from estimates that the

There have been five well known extinctions on this earth. The one most well known is the mass extinction that ended the dinosaurs. Mass extinction is often described as the elimination of a large number of species in a short period of time. Despite what many think, the elimination of species is almost commonplace at this point. The Earth is currently in the middle of a sixth mass extinction, and it’s been caused by the human race.

used to roam the lands and seas of planet Earth. The extinction of such species is a widely known

The asteroid impact extinction theory began in 1980 with Luis and Walter Alvarez, a father and son team. They theorized that an asteroid struck the Earth at the close of the Cretaceous period, causing devastating effects and mass

They say as mammals continued to evolve, they drove the dinosaurs into extinction (“What Killed the Dinosaurs”). “Not only did mammals likely compete with dinosaurs for resources, many species survived the end-Cretaceous extinction and subsequently came to dominate Earth.” (“What Killed the Dinosaurs?”). This is primarily because the early mammals were a lot smaller than the mammals that exist today. “Some of the world's earliest mammals were the multituberculates, a group of small rodent like animals that first emerged on Earth about 165 million years ago.” (Welsh, Jennifer). Scientists predict that any mass extinction event that caused animals to go extinct affected larger animals than it did the smaller animals, such as mammals ("Dinosaurs Became Extinct 'due to Laying Eggs'"). Mammals remained small for almost 100 million years, while they out competed small and baby dinosaurs for food, shelter and resources until they were extinct. Once the dinosaurs were out of the way mammals were able to evolve and grow large in size like the mammals that exist today today (LiveScience). Fossil evidence sheds some light on this theory as well. Fossils of mammals believed to date back to about eighty five million years ago show that mammals began to change rapidly and grow. “This matches up with other mammal groups, including recently discovered species from the Late Cretaceous (between 100 million and 65 million years ago) showing highly specialized