Examining the Cretaceous-Paleogene Extinction Event Over 98% of all organisms that have lived on Earth are now extinct. A mass extinction event occurs when a large number of species die out within a small time frame (relative to the age of Earth). Mass extinctions are intensively studied for both cause and effect, as there is usually room for debate regarding catalysts that precede the extinction and the massive influx of new biological species that follows. There have been five major mass extinctions, dubbed the “Big Five,” that have wiped out at least 50% of the species living at those times. The most well-known mass extinction of the Big Five, with the decimation of every species of non-avian dinosaur, is the Cretaceous-Paleogene extinction event (K-Pg). The K-Pg extinction occurred as ongoing natural disasters followed by an asteroid collision with Earth, which affected plant life, animal life, and hydrology (Cobb, n.d.). Some paleontologists believe that the global ecosystem had already been in decline before the final blow, an asteroid, destroyed much of life on Earth. Continental drift and seafloor spreading may have shifted oceanic circular patterns, causing dramatic changes in sea level and the Earth’s climate.
The possibility if a meteor strike as the cause of extinctions is discarded, something that most specialists agree on. There is no evidence of any meteor crater big enough or recent enough to be accountable for it; there are no “elements that are common extraterrestrially but less so on Earth, such as iridium, and no sign of a tsunami or other phenomena following the impact.” The extinctions where also very selective and occurred over a very long period of time. If a “one shot” catastrophe had been the cause it would have affected all species at the same time and in similar
The question of what caused the extinction of megafauna during the Late Pleistocene period is one that archaeologists have struggled to answer for decades, but why should it matter? Discovering with certainty the cause of megafaunal extinction would simultaneously prove or disprove any of the proposed implications of each existing theory regarding this massive extinction.
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. This essay will explain how a once blossoming progressive era turned into Earths most catastrophic event.
The disaster theory, Gould claims, is an example of good science. It has testable evidence and has an impact on studies in other fields of science, it develops further and explains why the extinction of dinosaurs occurred simultaneously with other events. This theory suggests that a large comet hit the Earth sixty five million years ago, causing the cloud of dust to rise into the sky and to block sunlight. As a result, world temperatures went down significantly, the ice age bega...
Being that there was not enough sun light it made it impossible for plants and animals to survive. Which lead to a deadly chain of events. Without the sun, all the plants died; without the plants, all the plant-eaters died; and without the plant-eaters, all the meat-eaters died. Which sounds quit reasonable. Some evidence even seems to indicate that all the dinosaurs had died before the meteorite hit. This change was said to be too much for dinosaurs to survive.
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. The Cretaceous Event ( often shortened to K-T event) Of the animals that were killed off were the flying reptiles (pterosaurs) and the last few mosasaurs and plesiosaurs, both early marine reptiles. Many mollusks and species of microscopic plankton were killed. Terrestrial plants suffered mass extinction as well. Almost 60% of terrestrial plants were lost. This led to high extinction rates among insect populations, especially insects that were highly specialized to feed on just a few types of plants had it the worst. It took approximately 9 million years for the global insect populations to recover from the Cretaceous extinction. Immediately after the extinction, the earth saw an explosion of short term species who respond well to fire, or other external disturbance. Evidence of the catastrophe comes from a thin rock layer deposited worldwide just after the impact. It is dominated by fossil plants whose descendants recover quickly after fires of other disturbances, such as Fire Weed in Alaska. The causes of the Cretaceous extinction are still being debated by paleontologists. Scientists agree that the main cause of the extinction was a...
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.
Throughout history our world has undergone and experienced all sorts of changes that have shaped the world into what we see it today. The most significant events included disasters like the extinctions of organisms. Out of all the extinctions, the most influential was the Permian Mass Extinction. During the Paleozoic era roughly eighty five percent of living species died and became extinct due to the Permian mass extinction. This illustrates how severe an event like the Permian mass extinction actually was. With such a prodigious magnitude, it’s important to note the consequences and results that aroused. In this case the most devastating consequence was its influence and alternation on the history of life. In addition, it is crucial to see the factors responsible for causing such immense extinctions, ultimately leading to what we call the Permian Mass Extinction.
So agreement over dinosaur extinction is far from unanimous, and fossil’s continue to be found that adds to the knowledge about how dinosaurs lived and died. The climate change theory still holds sway over some scientist, that refute that the chicxulub impact was the major reason for the dinosaurs extinction. Some evidence from the 65-million-year-old lava flows in india hint that a giant, gaseous volcanic plume might have initiated global climate change that threatened and killed the dinosaurs. Scientist continue to research and make more conclusions on what killed
Sixty-five million years ago the dinosaurs died out along with more than 50% of other life forms on the planet. This mass extinction is so dramatic that for many years it was used to mark the boundary between the Cretaceous Period, when the last dinosaurs lived, and the Tertiary Period, when no dinosaurs remained. This is called the Cretaceous/Tertiary (or K/T) boundary, and the associated extinction is often termed the K/T extinction event.The name "Tertiary" is a holdover from the early days of geology, and many geologists now prefer the term "Paleogene" for the time period that immediately follows the Cretaceous. These scientists refer to the Cretaceous/Paleogene or K/P boundary, which represents the same moment in time as the K/T event. Since their discovery in the nineteenth century, the reason for the dinosaurs' demise has been a matter of speculation and debate. Early paleontologists, working prior to Darwin's theory of evolution by natural selection, suggested that
seems like it happened so sudden, as geologic time goes, that almost all the dinosaurs
The discovery that birds are a type of dinosaur showed that dinosaurs in general are not, in fact, extinct as is commonly stated.[156] However, all non-avian dinosaurs as well as many groups of birds did suddenly become extinct approximately 66 million years ago. It has been suggested that because small mammals, squamata and birds occupied the ecological niches suited for small body size, non-avian dinosaurs never evolved a diverse fauna of small-bodied species, which led to their downfall when large-bodied terrestrial tetrapods were hit by the mass extinction event.[157] Many other groups of animals also became extinct at this time, including ammonites (nautilus-like mollusks), mosasaurs, plesiosaurs, pterosaurs, and many groups of mammals.[9] Significantly, the insects suffered no discernible population loss, which left them available as food for other survivors. This mass extinction is known as the Cretaceous–Paleogene extinction event. The nature of the event that caused this mass extinction has been extensively studied since the 1970s; at present, several related theories are supported by paleontologists. Though the consensus is that an impact event was the primary cause of dinosaur extinction, some scientists cite other possible causes, or support the idea that a confluence of several factors was responsible for the sudden disappearance of dinosaurs from the fossil record.[158][159][160]
Because the CO2 levels are rising, the ice caps are melting and many more animals can become extinct. When pangea started splitting, there was a lot of volcanic activity, which cause the death of many dinosaurs. A meteor also hit earth and the mass extinction of many land and marine animals happened. There have been five mass extinctions in Earth’s history. The worst one wiped out ninety-six percent of marine life and seventy percent of land organisms. This took millions of years to recover.
Throughout history there have been many different reasons for the extinction of species. The earliest known reason was 64-66 million years ago when scientists believe a meteorite struck earth causing the extinction of the dinosaur and of 85% of the species existing at the time (Sherry, 2). Another major problem is the introduction of species into a new environment. Most introduced species become pests because they have no natural enemies and can easily out compete native species that have natural enemies, thus overpopulating a certain environment (Sherry, 5). The main causes of extinction are habitat destruction, commercial exploitation, damage by non-native species introduced into the environment, and pollution (Definition of endangered species). Out of all of these, habitat destruction is the major source of extinction. It is thought that at least 4,000-6,000 species become extinct each year in the rain forest alone due to burning acreage to make room for farm fields (Today’s situation). Most of the human caused extinctions occurred during the Industrial Revolution, which was 250 years ago (Sherry, 2). Another significant reason for the decline, if not extinction of species is hunting and poaching animals. A good example of this is the near extinction of the American Bison due to over hunting. Between 1870 and 1875, 2.5 million Bison were killed annually. In 1883 the last significant herd with around 10,000 members was done away with. By 1990 there were only an estimated 500 plain Bison remaining in the United State (Direct Causes). These are all key reasons for the extinction of species and if we can avoid them then we may prevent the future extinctio...