Essay Example on 5 Mass Extinctions: Understanding the Cretaceous Period

Introduction

Scientists from different research disciplines, such as evolutionary biology and geology across the world identified that there had been five primary extinction events in the history of life. For a vent to be categorized as mass extinction, there have to be more than half of forms of life are known in a particular time must be extinct. One of the best-known mass extinctions on earth is the fifth mass extinction, referred to as Cretaceous Mass extinction. The Cretaceous period is best known for the dominance of big reptiles (dinosaurs). This period is referred to as the Mesozoic Era, a time where dinosaurs dominated most parts of the habitats on the land. The mammals were small, and they are believed to have been nocturnal in order to avoid the dinosaurs. The end of the cretaceous period gave a chance for mammals to dominate other species. the extinction of this period occurred nearly 65.5 million years (Schoene et al. 2018). Several species were lost after the on after the end of the Cretaceous period; some of these animals include flying pterosaurs, non-avian dinosaurs, mosasaurs, ichthyosaurs of the sea and plesiosaurs. Also, some of the significant marine invertebrates were extinct, including groups of cephalopods, bivalves, and ammonites. Several pieces of evidence of geological materials indicate that a natural disaster caused this action. This paper, therefore, explores cretaceous extinction.

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Cause of Cretaceous Mass Extinction

Cretaceous extinction is known as one of the sudden mass extinctions of about half of the species which were found on the earth. Geological evidence shows that extinction was caused by a massive occurrence of the asteroid of 10 to 15 kilometers- 9 miles wide, which devastated the environment of the earth as a result of a lingering impact that altered the process of photosynthesis of several and plankton in water bodies as well (Schoene et al. 2018). The impact of this occurrence includes the effect on Creator in the Yucatan Peninsula. A place in Mexico currently filled with rocks on the surface of the land that dates back to the time of extinction. It is thought that the impact caused a cloud of enormous dust which covered the atmosphere and covered the planet. This dust prevented enough amount of light from reaching the surface of the earth, which affected the rates of photosynthesis.

Theories Explaining Cretaceous Mass Extinction

Theories regarding mass Cretaceous mass extinction have been proposed intermitted by the European and North American geological scientists for over 250 years. Some of the theories perceive the extinction of biological components as the primary causative agent. The proposed theoretical causes of this phenomenon have included the impact of comets or asteroids, the passage of planetesimals close to planet earth, and transient increases in cosmic radiation (Longrich et al. 2015). Over time, these theories have significantly extrapolated based on observation of astronomical events to suggest that most of the extraterrestrial had an impact on the earth in the past. It was until the late century when these theories showed scientific tests of temporal quirks between mass extinction and the terrestrial impacts of extraterrestrial materials. The impact of comets was the first hypothesis to propose such tests. The theory of impact-extinction by Luis Alvarez, together with his colleagues, is on the theories with direct scientific evidence of these occurrences (Longrich et al. 2015).

The test which was conducted did not provide scientific properties to explain the cause of Cretaceous mass extinction. The theories of extraterrestrial effects on the cause of this extinction have always utilized the hypothesis of proximate and ultimate impacts of extinction. The definition of these combinations has always varied significantly from time to time and category to category. In general, these theories have evolved more rapidly since they were presented and explored based on scientific interest. Therefore, the impact -extinction theory is one of the theories that have bee subject to tests and shows scientific evidence, and the impact of the fall of comets is linked to environmental and biological effects.

Description of Extinction

Cretaceous is known as the last period of big reptiles, including dinosaurs, and the extinction process was savers and devastating, causing the complete disappearance of these critical pieces on the planet earth. Mass extinction is deadly and caused by adverse effects; it was severe, rapid, eliminating and selective. Cretaceous extinction is the most recent extinction which occurred through a fall of comets, causing a deadly impact on the earth. It is estimated that 76% of the species were lost in this period of extinction. The phenomenon happened in about 66 million years ago when a giant asteroid falls into the earth service- waters a location is currently known as Yucatan, moving at a speed of 45,00 miles per hour (Halliday & Goswami 2016).

The impact of this slam was massive, leaving a crater of more than 121 miles wide. This occurrence caused large volumes of dust, sulfur, debris covering the atmosphere. This brought about an adverse cooling on the earth, wildfires lighting land of about 900 miles wide, and a severe tsunami that occurred as a result of the impact of the asteroid (Halliday & Goswami, 2016). The ecosystem that supported the survival of the dinosaurs and other vast species of animals began to collapse. Global warming increased as it was fueled by the series of volcanic eruptions occurring at the Deccan Flats, this is thought to have aggravated the extinction process, the scientist believes that the eruption of these mountains was linked to the impact of the asteroid. the event is thought to have affected all the continents as the extinction of all extinct animals of this era were found in different places of the earth. Biologically, the extinction of most of the species that rely on photosynthesis declined as the particle blocked sunlight that facilitates this process (Aberhan & Kiessling, 2015).

Evidence of extinction

There are several evidence showings that extinct animals existed. In North America, there are temporal sequences that bets represent the events that caused the extinction. This is seen from the existence of a visible discrepancy occurring between the late Maastrichtian Pollen and post- boundary fern point. Today the most of the information about dinosaurs bearing rocks that exist in the form of K-Pg boundary is found in the West part of North America. Also, the scientific census shows the impact of the asteroid at the K-Pg boundary left deposits of Mega tsunami as well as sediments around the Gulf of Mexico and areas of Carrabin sea, and this despot is to have occurred as a result of colossal waves generated by the impact of the comets (Halliday & Goswami, 2016).

Mass extinction of some of the marine species such as Plankton appeared to have been sudden and occur right at the boundary of K-Pg. the extinction process was slower in some of the species, and the gradual process led to a gradual reduction in marine fossils. Most of the fossils of the extinct animals exist within the sedimentary rocks, which are thought to have been deposited as a result of the impact (Aberhan & Kiessling,2015). Further scientific analysis shows that most of the process of extinction was in progress in the Cretaceous period, and they overlapped at some period, as a result of mass extinction, the diverse marine species as climate change such as a rapid increase in temperature. Recently, deposits of fossiliferous sedimentary materials have been found along the Gulf of Mexico regions, including deposits of mangrove-type of life system.

Extinct Organisms

The organism that went to extinct includes, chorister, turtles, Lepidosauria, pterosaurs, and birds. Generally, terrestrial's organisms, mammals, insects, birds, Amphibians, marine life (fish, and most of the reptiles) and plants went to extinct (Longrich et al. 2015). Most of the dinosaur species became extinct; other species include foraminifera and non-avian dinosaurs. Marine invertebrates that went became extinct include, gryphaeid (Bivalve) and inoceramid (Bivalve) Extinction was more adverse in animals' aquatic animals that terrestrial animals because the marine animals are more relent on primary production from Phyla plankton and those living on the floors of the ocean, depends on detritus.

Those organisms whose food chain was significantly altered rapidly went to extinct. For instance, the ammonites are thought to been depending on mosasaurs as a primary source of food, and these species became extinct at the boundary. Also, the most abundant animals which survived on a massive amount of air were greatly affected as the rest of the dust which the atmosphere. Most of the terrestrial animals disappeared after the extinction of the terrestrial plants they relied on as part of their habitat. The extinction of these, however, gave a chance to some of the animals to dominate, new habitat developed, new species also emerged, promoting the evolution of life on the earth after extinction. The extinction of dinosaurs benefited the mammals, which led to the rise of human beings as well as other species of animals and plants that exists today (Vellekoop et al. 2016).

Extinction Today

Scientist suggests that today, extinction is an ongoing process. Unlike in the impact of comets, extinction is more gradual. Extinction is occurring more faster today than it would have happened naturally. Several factors contributing to this phenomenon include climate change, global warming, planet's physical changes; these factors trigger the extinction of other several species, and in the future, this will be seen as another mass extinction. The planet is currently experiencing a crisis of biodiversity. There is a possibility of losing over a million species of animals and plants because of the rapid increase in human active-ties that are harmful to the environment. Some of these activities include hunting, deforestation, and overfishing. Also, there are severe factors that threaten some of the species, which include invasive species, human trade, diseases, and pollution.

Summary

Cretaceous mass extinction is one of the most destructive events that took place about 65 million years ago. The extinction caused the permeant disappearance of several animal and plant species on planet earth. There have several scientific pieces of research on the cause of this extinction. There are deferent theories that have been developed to explain the cause of this event, which includes the impact of comets or asteroids, the passage of planetesimals close to planet earth, and transient increases in cosmic radiation. Most of the studies show that asteroid is the major of extinction as it led to saver environmental effects.

It is thought that massive comets fall on the earth's service - water a place in peninsula Mexico. The size of the asteroid is estimated to have been about 6 miles in diameter. On hitting the earth's service at the end of the cretaceous period, it led to a saver impact that produced dust covering the atmosphere. The dust deleteriously reduced the amount of sunlight reaching the surface of altering the rate of photosynthesis in terrestrial plants and affect the plankton in the water. As terrestrial and aquatic plants died, the food chain for most of the animals was substantially damaged; this includes eliminations of several herbivores and carnivores and reptiles. The impact father extended as it causes wildfires, volcanic eruptions, and falls back of debris.

This event led drove many species of animals and plants into extinction. Most of the reptiles, mammals, birds, fish, and plants became extinct. The extinctio...