Thorium-Uranium Dating

They aren't able to adapt and figure their new environment quickly enough. Documents B, E, and F each tell about a specific organism that was affected by the dramatic climate change, these organisms spend years trying to perfect their home, diet, and children. Document B states, “Organisms are dying out, especially in certain areas where they aren't able to adapt as quickly, but they don't have the chance to do all that work over, so they have to live with that and start over until they reach safety again.

Earth has experienced many episodes of dramatic climate changes with different periods in earth history. There have been periods during which the entire planet has been covered in ice and at another time it has been scorchingly hot and dry. In this regards, earth has experienced at least three major periods of long- term frigid climate and ice ages interspersed with periods of warm climate. The last glacial period which current glaciers are the result of it, occurring during the last years of Pleistocene, from approximately 110,000 to 10,000 years age (Clayton, 1997). Indeed, glaciers present sensitive indicators of climate change and global warming and by estimating and monitoring the dynamic evolution of these ice masses, several

It was during the Pleistocene period when the most recent episodes of global cooling from the last Ice Age took place. During this time much of the World's temperate zones were alternately covered by glaciers during cool periods and then uncovered during the warmer interglacial periods when the glaciers retreated.[110]

Encyclopaedia Britannica also states that it is “proved to be a versatile technique of dating fossils and archaeological specimens from 500 to 50,000 years old” (1998). This method of age determination is dependent upon the decay of nitrogen and radiocarbon (Carbon-14) (Encyclopaediea Britannica, 1998; Opinions of Radiocarbon Dating, 2011). Carbon-14 is continually formed in nature by the interaction of neutrons with nitrogen-14 in the Earth’s atmosphere (Encyclopaediea Britannica, 1998; Opinions of Radiocarbon Dating, 2011) and all living things exchange the gas carbon-14 with the atmosphere surrounding them. The amount of carbon-14 exchanged into the living organism is perfectly balanced with its surroundings, but when an organism dies, they stop taking in the gas and that equilibrium is damaged. Because Carbon-14 slowly decays at a known rate called its “half-life” in a dead organism, scientists can figure out how long ago it had stopped exchanging carbon with its atmosphere. Thus, its age can be determined by measuring the amount of Carbon-14 in a sample (Hirst, 2017; Opinions of Radiocarbon Dating, 2017; Oxford Radiocarbon Accelerator Unit Research Laboratory for Archaeology, n.d.; Earthsky, 2017; Cram, 1993). With the utilisation of Radiocarbon Dating, scientists have been able to discover that Lindow

Based on these ideas, Martin introduced the implications of the overkill hypothesis. For one, he asserts that in the absence of better material for dating the colonization of Clovis people in North America, it is reasonable to equate the date of extinction of megafauna with the date of colonization starting in Beringia and traveling southward (Martin P.S. 972). Martins model also implies that the diet of the Clovis hunters during the time of megafauna almost entirely consisted of megafauna.

From both the title of the chapter and the introduction by Dr. Shubin, this chapter begins with a focus on teeth. Because the function of teeth is to break down food before it enters the esophagus, the different shapes of teeth can represent many different things about the organism it belongs to including what type of eater it was (carnivore, herbivore, or omnivore). Teeth are the hardest tissue (not bone) in the human body and therefore fossilize well. As Dr. Shubin stated in chapter one, there must be many points that permit a fossil to make any kind of scientific conclusion. Obviously, the state of their presence is important, so the fact that teeth preserve well allows for them to be great specimens for analysis. Dr. Shubin and his team analyzed fossilized teeth in areas as different as Nova Scotia and the Arizona desert. Studying different fossils in these diverse regions allowed the team to see that mammalian and reptilian teeth are very different. For example, mammalian teeth differ from organism to organism to fit with the organisms need (Cheetahs that eat only meat will have different teeth than deer who are herbivores) and are replaced only once in the lifetime of the organism while reptilian teeth are usually sharp and are constantly replaced if damaged. These differences allowed scientists to characterize fossils as either a reptile or a mammal. Similar to Tiktaalik discussed in chapter one, the discovery of fossils that were part reptile and part mammal allowed the researchers to see that mammals evolved from reptiles, and further supported the theory of evolution. Further studies yielded even more

There were multiple issues identified in opposition to this claim, the first being the lack of evidence for contemporaneity between the arrival of humans with the extinction of the megafauna. Without consensus on these two time periods inferences about the cause of megafaunal extinction cannot be made. Judith Field suggests that the site at Cuddie Springs demonstrates long periods of co-habitation between humans and now extinct megafauna, which generates issues in the rapid extinction aspect of Flannery’s hypotheses (“Taming the Fire”, 1998). In addition Bowman (1998) also proposes the evidence for primarily human induced megafaunal extinction is unsubstantial and possibly caused by numerous factors including climate and habitat changes (pp.

The ecological conditions might have changed quickly and the species was not able to adapt to those conditions, which eventually lead the species to go extinct.

Hypothesis supporting climate change as a factor in Neanderthal extinction has taken on two forms - Neanderthals inability to adapt to harsh environments and prey extinction. Traditionally, Neanderthal extinction has been contributed to sudden climate change in which the species was unable to adapt (Houldcroft & Underdown 2015). Despite the fact that Neanderthal fossil exhibit ecomorphological characteristics that suggest they were adapted to colder ‘ice age’ environments; there is considerable evidence that supports the hypothesis that climatic changes are responsible for their sudden disappearance (Rae et al 2011; Stewart 2005). Neanderthal species were unlike any

Although a cause for the end-Pleistocene extinction has yet to be agreed upon, I will be discussing and evaluating the four most debated theories. These are the overkill hypothesis, the climatic hypothesis, hyperdisease, and the Younger Dryas impact hypothesis. The overkill hypothesis is the argument that the humans caused the end-Pleistocene megafaunal extinction, through over-hunting.

Because dinosaurs are animals that lived millions of years ago, we are entirely dependent on the fossils that they have left behind for any understanding that we hope to gain. As any paleontologist will tell you, fossil hunting is difficult. There are no certainties, no guarantees. A certain amount of luck is as valuable as any scientific knowledge.

I have learned that where I lack discipline in editing my papers, I excel in going with the flow of things. Without having to worry about the structure or order of my paper, I ‘am extremely capable of creating a story or paper without rushing myself. I feel as if I’am talking with my hands when type the words down on to this digital piece of paper. My spelling and my function mean nothing because they only hold me back if i choose to let them do so. MY biggest problem was when i work; the fear of breaking the english language rule. Now if i concentrate on just writing the essay or writing the research paper without worry about all the rules, I find myself able to writing hundreds of words in the matter of minutes . Where it use to pain me to write so clearly and thoughtfully, now writing without causation has let me be able to write more fluidly and creatively. As of right now I have

There is another theory proposed that posits that rapid sea level regression followed quickly by transgression caused the mass extinction, at least in the marine realm. According to Schoene and Geux (2010), δ18O values from fossil oysters suggest cool ocean temperatures immediately following the negative δ13C excursion followed by a period of warming. As shown in figure 2, during a time spanning approximately 300,000 years there was a positive carbon isotope anomaly (corresponding with a decrease in sea level along with cooling and glaciation) followed by a period of higher sea levels and a negative carbon isotope anomaly. These findings are consistent with rapid sea level regression-transgression lasting only approximately 290,000 years, which can only be explained

Not to mention “...both groups emphasized that climate change would play an increasing role in species decline…” (Gilman). Climate change is still a controversial topic to some, but many scientists have proven that it’s true. In fact, Neil Degrasse Tyson has given evidence to prove its truth and already informed the world that it’s too late to fix people’s mistakes (Neil). The extinction of species has been caused in certain instances by climate change, which is only getting worse. People have continuously altered the environment to the point of harming other species. The human race’s tendency to destroy an environment greatly impacts the plants and animals residing there. To be more specific, “Human destruction of animal and plant habitat...appear to be having a major impact on extinction rates” (Wilson). Environmental degradation and habitat destruction are both key players in the extinction of many world species. The impact people have had on the environment is much bigger than most anticipate, as they both destroy and intervene with the environment.

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.