Mass Extinction

Invasive species are an important mechanism of this extinction because there are many different species of things that have been relocating. An example of this she talks about in the book is how the American chestnut was effected by humans. Humans introduced the chestnut to a fungus that made it poisonous to other species. Which

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).

Extinction: Most species become extinct because they can’t cope with the environmental change, and also because of introduced species that turned into competitors for

A mass extinction is an event in which at least 25-75% of species in the global environment are eradicated in a short period of time. Where as a regional extinction event is when the extinction is confined to a specific zone. Five mass extinctions have occurred throughout time, two of the most well known of these are the Permian and Cretaceous extinction events.

There are a lot of theories about why the K-T extinction occurred, but a widely accepted theory was proposed in 1980 by a physicist named Luis Alvarez and his son Walter Alvarez who was a geologist. the theory is that an asteroid 4-9 miles (6-15 km) in diameter hit the Earth about 65 million years ago, creating the Chicxulub crater at the tip of Mexico's Yucatán Peninsula. The crater is more than 110 miles in diameter and 12 miles in depth. It is one of the largest confirmed impact structures on Earth; The impact would have penetrated the Earth's crust, scattering dust and debris into the atmosphere, and causing huge fires, tsunamis, severe storms with highly acidic rain , seismic activity, and perhaps even volcanic activity . The impact could have caused chemical changes in the Earth's atmosphere, increasing concentrations of sulfuric acid, nitric acid, and fluoride compounds. The heat from the impact's blast wave would have incinerated all the life forms in its path. The evidence for the impact was first discovered by Walter Alvarez and some of his colleagues. They found that rocks laid down precisely at the K-T boundary contain extraordinary amounts of the metal iridium. The dating is precise, and the iridium layer has been identified in more than one hundred places around the Earth. Where the boundary is in marine sediments, the iridium occurs in a layer just above the last Cretaceous microfossils, and the sediments above it contain Paleocene microfossils from the earliest part of the Cenozoic. Iridium is much rarer than gold on Earth, yet in the K-T boundary clay iridium is usually twice as abundant as gold, sometimes more than that. The same high ratio is found in meteorites. The Alvarez group therefore suggested that iridium was scattered worldwide from a cloud of debris that formed as an asteroid struck somewhere on Earth. Shocked quartz was

The first thing to know about this particular mass extinction is the species that inhibited the earth

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.

The sixth mass extinction is on the way and could be as massive as the extinction that wiped out the dinosaurs (Kolbert, 2014). Before learning more about the sixth mass extinction, you’ll have to first understand what biodiversity is and what will happen when you tamper with it. According to Anup Shah, author of Why is Biodiversity Important? Who Cares, biodiversity means the variety of life on Earth or in an ecosystem. Every species plays an important role in the ecosystem or in the world, no matter how big or small. A way to incorporate this into easier terms is the food chain or food web. Without a certain species in the cycle, you’ll be losing another species and so forth (Shah, 2014).

The Cretaceous mass extinction had two theories on how and why it happened through the impact hypothesis. The first one was suggested that an asteroid collided with Earth 65 million years ago. Luis Alvarez and his son, Walter Alvarez found “high levels of the rare metal iridium” in the layers of the Earth during the periods of the Cretaceous and Tertiary located in Italy. Their proof is that it was the cause of extinction by an asteroid the size of 10 kilometers. The second impact hypothesis was from a crater that was found buried off the coast of Yucatan, Mexico. Due to the material that was thrown from the crater into the air, plant life could not receive sunlight to survive. The same goes for animals as the atmosphere was filled with dangerous

65 million years ago a mass extinction of the dinosaurs took place marking the end of the Cretaceous Period when dinosaurs lived and the beginning of the Tertiary Period when no dinosaurs remained (“Dinosaurs”). This period is also known as the Cretaceous/Tertiary, or K/T Boundary (“Dinosaurs”). Just what caused the mass extinction is still up for debate but the two main theories are either an impact from a huge asteroid or massive strain if

These discoveries and the search for answers led to work by a diverse group of scientists from a number of different disciplines finding evidence of a catastrophic event in the history of the Earth, and the hypothesis of an asteroid impact that would have led to mass destruction of life (plant and animal), including the extinction of the dinosaurs.

Though there is not one definitive explanation to explain dinosaurs' extinction, there are various theories that attempt to account for the mystery of their extinction. The theories that explain their extinction at the end of the Cretaceous period are the asteroid, the volcanoes, and the major climatic changes. The most popular theory for the extinction of the dinosaurs is that the Earth was hit by an asteroid or a comet. Was the impact actually the cause behind the dinosaur’s extinction? Or was it something completely different? An analysis of the evidence surrounding the extinction of dinosaur’s reveals that there are several different hypothesis that give theory on what might have happened.

One of the most widely accepted theories is the asteroid. In section 5, “Death of the Dinosaurs”, of a book written by Donald Prothero, he states that, “By 1990, the debate was no longer whether the impact occurred-that was clearly established” (Prothero). An article in TIME magazine states that, “About 66 million years ago, a six-mile wide (10 km) asteroid struck the coastline of the Yucatan peninsula” (Kluger). This theory was created in 1978

According to the research made by Alvarez (1980), it was due to an asteroid impact that single-handedly destroyed dinosaurs to extinction. Advocacy of this mechanism has been aided by the availability and tangibility of supporting evidence in the form of impact craters- the Chicxulub crater in the Yucatan Peninsula's date and timing of impact (dating produced an almost exact date of 65 million years ago), location, enormous size-170 km (Hildebrand et al.1991) and its high iridium content ( a metal not commonly found at the Earth's surface) make it seem that with a theoretical asteroid 10 km big caused the crater great damage at the end of the Cretaceous (Alvarez et al. 1980).

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