Several mass extinctions have occurred during the Earth’s history. The Cretaceous – Tertiary Boundary (K-T) Extinction caused the loss of at least three-quarters of all species known at that time including the dinosaurs. The cause of this mass extinction is a controversial subject among scientists but the fossil evidence of it’s occurrence is abundant.
The K-T Extinction occurred 65 million years ago. Many species perished in that extinction. Today evidence for this extinction can be seen in the fossil record. Biological, botanical and geological evidence at the Cretaceous – Tertiary Boundary show that some enormous event occurred that caused mass extinction of life on the Earth. Controversy about the cause of the K-T extinction exists with two main theories currently being in favour. One theory is called Intrinsic Gradualism and believes the cause of the K-T Extinction was a slow and gradual Earth generated event, caused by intense volcanic activity and the effect of plate tectonics. The second theory is known as Extrinsic Catastrophism and proposes that the K-T Extinction was caused by a sudden and violent catastrophic event such as the Earth being struck by a meteor or asteroid. The K-T Extinction supports the concept of Punctuated Equilibrium in evolution because surviving species evolved and others were exterminated. This creates the stepladder effect of evolution seen in the fossil record .
THE K-T EXTINCTION
The Cretaceous period occurred between 144 and 65 million years ago. The K-T Extinction is an event that happened at the end of this period 65 million years ago. By the beginning of the Tertiary period eighty-five percent of all species disappeared, making it the second largest mass extinction event in geological history (“The End-Cretaceous (K-T) Extinction”, accessed 2000).
Among the species that perished were the dinosaurs, pterosaurs, belemnoids, many species of plants, except ferns and seed-producing plants, ammonoids, marine reptiles and rudist bivalves. Severely affected organisms included planktic foraminifera, calcareous nannnoplankton, diatoms, dinoflagellates, brachiopods, mollusca, echinoids and fish. Mammals, birds, turtles, crocodiles, lizards, snakes and amphibians fared much better and were mostly unaffected by the End-Cretaceous mass extinction (“The End-cretaceous (K-T) Extinction”, accessed 2000...
... middle of paper ...
...pdated 1995, accessed 3 Sept. 2000), Dino Buzz – What killed The Dinosaurs ? – Current Arguments,
Lowood, H. 1998 (updated 7 Sept 1999, accessed 30 June 2000), Stanford Presidential Lectures and Symposia in the Humanities and Arts, Stephen Jay Gould,
Smith, P.L. 1997a (updated 1997, accessed 3 Sept. 2000), Biological Evidence,
Smith, P.L. 1997b (updated 1997, accessed 3 Sept. 2000), The Marine Realm,
Smith, P.L. 1997c (updated 1997, accessed 3 Sept. 2000), The Terrestrial Realm,
Smith, P.L. 1997d (updated 1997, accessed 3 Sept. 2000), Geological Evidence,
“Speculated Causes of the End-Cretaceous Extinction” (accessed 3 Sept. 2000),
“The End-Cretaceous (K-T) Extinction” (accessed 3 Sept. 2000),
Need Writing Help?
Get feedback on grammar, clarity, concision and logic instantly.Check your paper »
- Humans are very quickly dominating the globe. Today, the human population is around 7 billion people. Humans are populating at a rate of almost 220,000 per day. Humans are rapidly heading towards Earth’s carrying capacity. Earth has gone through five fully major extinctions before. We currently are in the process of Earth’s sixth mass extinction. This mass extinction is closely related in severity to the extinction of the dinosaurs. Earth’s extinctions are broken into three different areas. The first area was the large number of animals caught by hunter-gathers.... [tags: World population, Overpopulation, Human]
1827 words (5.2 pages)
- ABSTRACT Several mass extinctions have occurred during the Earth’s history. The Cretaceous – Tertiary Boundary (K-T) Extinction caused the loss of at least three-quarters of all species known at that time including the dinosaurs. The cause of this mass extinction is a controversial subject among scientists but the fossil evidence of it’s occurrence is abundant. INTRODUCTION The K-T Extinction occurred 65 million years ago. Many species perished in that extinction. Today evidence for this extinction can be seen in the fossil record.... [tags: K-T Extinction]
2446 words (7 pages)
- Cretaceous Extinction Event Causes, Evidence, and Effects on Biodiversity The most significant event of the Cretaceous era came at its end. Nearly 65 million years ago, the second most severe mass extinction in earth’s history occurred. This resulted in the loss of around 80% of species living at the time. Though nowhere near as severe as the end-Permian mass extinction, the end-Cretaceous extinction is the most well known mass extinction event. This is due to the violent event that caused it the extinction, as well as the chapter of earth’s history that it closed: the Dinosaurs.... [tags: mass extinction, dinosaur, asteriord]
1325 words (3.8 pages)
- Throughout Earth’s history there have been many changes. These changes have consisted of temperature fluctuations, atmospheric differentiations, extinctions of various plant and animal life, etc. Over time everything seems to have evolved in some way form or fashion. However, the Permian Era extinction was different from all the rest. This extinction affected every form of life, but especially the marine life. Researchers have stated that 93-97% of all Earths species went extinct during this period of time.... [tags: Paleozoic Era, global warming, species, Earth]
1113 words (3.2 pages)
- ... 70 million years later, we have more complex life, which has moved out of the ocean making use of the land. The Late Devonian extinction is not a single event but a myriad of smaller scale extinctions such as the Kellwasser event, and the Hangenberg event that are combined to create the entirety of the major extinction event. The third mass extinction happened approximately 245 mya and is referred to as the Permian–Triassic extinction event. “More than half of the families of living things died out, and as many as 90 to 96 percent of the planet's marine species were lost.... [tags: history and evolution of Earth]
718 words (2.1 pages)
- We are on the cusp of the sixth mass extinction, as estimated the event to be occurring within 2200 years. Scientists have evidences supporting this statement with the extinction rates and magnitudes, and comparing the present conditions to the past “Big Five”—the previous five mass extinction events. Mass extinction is generally known as the forever disappearance of 75% of lives in the globe, therefore species lost is the main driver of such extinction events. With the current high extinction rates and increasing trend of extinction magnitudes, the sixth mass extinction is expected.... [tags: Volcanic Eruption, Climate Dynamics]
1636 words (4.7 pages)
- As titled: Are We On The Cusp Of The Sixth Mass Extinction Event. Yes, we are indeed, as we, here defined as all the lives on the Earth at the moment. Mass extinction is times when the Earth loses more than three-quarters of its species in a geologically short interval (Barnosky et al., 2011). In addition, according to the Oxford Dictionary of Geology and Earth Sciences edited by Michael Allaby (2013), mass extinction is defined as the Earth has been taken place environmental catastrophe, removes many groups from environment from record and not replaced, and ecosystems collapse.... [tags: environmental catastrophe, Geology]
608 words (1.7 pages)
- Mass Extinction in the Precambrian As the decades pass, technological advances have enabled researchers, entrepenures and pondering minds the ability to discover more and more about every aspect of our very existence. Over the past three decades the evolutionary tree of life has been expanded at least seven times over. Major advances have been made in the area of evolution to open the eyes of many to the extensive history of the earth. For the very first time, we have tangible knowledge that life evolved and grew to become a flourishing success during the young ages of the Earth.... [tags: Papers]
444 words (1.3 pages)
- Earth Faces a Sixth Mass Extinction Scientists in Great Britain have been studying the distribution of birds, butterflies and plants for the past 40 years and the results from these studies suggest that the Earth is heading towards another mass extinction, and this one may have its roots in human activity. Within the four billion years that Earth has been around, it has already experienced five mass extinctions. The most recent, and most well known occurred 65 million years ago and caused the extinction of the dinosaurs.... [tags: Exploratory Essays Research Papers]
1252 words (3.6 pages)
- IntroductionThink of a world which existed 290 million years ago. As you look out over the terane in front of you, you think that you are on an alien planet. You see volcanoes spewing ash and lava. Beside them is the ocean which is swarming with many different species of echinoderms, bryozoans and brachiopods. As you look down onto the sea floor you are amazed at the countless number of starfish and urchins. Some animals leave you can't even describe and you have no idea even what phylum they belong to.... [tags: essays research papers fc]
5677 words (16.2 pages)