The cretaceous period and the aftermath
The Cretaceous Period and the Aftermath Imagine a great, thickly muscled dinosaur. Got it? See those serrated teeth? And the great yellow eye that is pondering whether you are food or foe? Now, imagine something that can kill this beast and all of its kind. This “something” is called the Cretaceous Tertiary Extinction event, and it occurred 65. 5 million years ago, and killed all the dinosaurs, and affected the process of evolution forever afterward. The Cretaceous Tertiary Extinction Event was actually a geologically short period of time. It is known as the K-T extinction event.
It’s associated with the geological signature known as the K-T boundary. The K-T boundary is a thin band of sedimentation found in various parts of the world. The thin band of sedimentation marking the K- T boundary line Did you know that the K stands for Cretaceous period? Guess someone didn’t know how to spell! The T stands for Tertiary period. This boundary marks the end of the Mesozoic Era, and it marks the beginning of the Cenozoic era. This was a large scaled mass extinction event. It may have been caused by one or more catastrophes.
On March 4, 2010, a panel of 41 scientists agreed that the Chicxulub asteroid riggered the mass extinction. Although, several impact craters such as in the Deccan Traps may have caused it. With such a catastrophic The Chicxulub Crater in Mexico event as this, evolution is sure to occur because of it. Charles Darwin’s Theory of Evolution Evolution occurred once organisms were formed. Our understanding of evolution does not depend on our non-understanding of how it began. Right now the scientists believe that complex life cam from simple chemical reactions.
It is unclear how this happened, and scientists don’t understand how it happened. Not much is clear about he structure of the first living things and life. Also, there is no scientific consensus on how evolution began. But what we do know is that this event killed the dinosaurs and set evolution in motion. Evidence of the Deccan Traps on a hillside The Deccan Traps are one of the theories of dinosaur extinction. These were a series of floods that was thought to have been the gradual extinction of the dinosaurs. The Deccan Traps were thought to have lasted over 2 million years.
Recent evidence shows that the traps erupted over 800,000 years ago and may have led to the extinction. An artists idea of the cause of dinosaur extinction Another theory is a multiple impact event. Some evidence of this theory is that the possibility of simultaneous multiple impacts that caused the extinction. Yet another theory is multiple causes. Some could have been volcanism, marine regression, and extraterrestrial impact. Also, terrestrial and marine communities were stressed. Lastly, the most probable cause of the dinosaur extinction was an impact event. So this is what most scientists think happened.
An asteroid hits earth, during the time of K-T boundary. How they know that it was most likely an asteroid is ecause inside of an asteroid is iridium. Guess what else contains iridium? The K-T boundary sedimentation line, that’s what. So then a dust cloud from the asteroid impact blocks the sun for a year or less. This injects sulfuric acid aerosols into the atmosphere. The dust cloud then leads to 10-20% reduction of sunlight reaching the earth’s surface. In turn, this inhibits photosynthesis. It takes 10 years for aerosols to dissipate. The aerosols would account for the extinction of plants and phytoplankton.
Then, it would produce high oxygen levels. This supports the intense combustion of he brush and tree. It makes widespread fires, and increases C02 content in the atmosphere. The wildfire leads to the greenhouse effect, and kills the most vulnerable organisms after impact. The greenhouse effect produces acid rain, which sounds dangerous, but if only a minor effect, and lasted for only 12 years. The acidity of the rain was actually neutralized by the environment. The animals vulnerable to acid rain effects actually survived, like frogs and such. Showing that the rain contributed to the effect very little.
The hypothetical asteroid that would have caused ll this might be the Chicxulub crater in the Yucatan peninsula, Mexico. The size of this asteroid compared to their estimations of the hypothetical asteroid is very close. Leading to their conclusion that this MIGHT be the asteroid that causes the Cretaceous-Tertiary event. If you doubt that an asteroid could do all this damage listen to this. According to scientist’s calculations, a 10-25 km (6. 21-15. 53 miles) space rock hit the Yucatan Peninsula. The impact would have released the same energy as 100 trillion tons of TNT, or over a billion times the energy of the bombs dropped on
Hiroshima. So, because this is all hypothetical, scientists searched for some real evidence of an unnatural extinction. And boy, did they find it. One of the Campanian Rocks The Campanian rock formations are an example of the evidence. They show a greater diversity of dinosaurs than any other. The Maastrichtian rocks contain the largest members of several clades. A clade is like a “branch” on the “tree” of life. Some of these members of the rock formation are Tyrannosaurus, and Triceratops. All of this suggests that food was plentiful prior to the mass extinction.
Also, in addition to rich inosaur fossils, there are also many different species of plant fossils. These illustrate the reduction in plant species the extinction cause. During the extinction, due to the inhibition of photosynthesis, the most of the plant population died. So, after the K-T boundary the dominant plant species are the Angiosperm pollen grains. Did you know that the most informative rocks containing dinosaur information is located in North America? Yes, mostly it is located in Hell Creek, Montana! Another entire species was also affected.
Everyone knows that the dinosaurs and lant species were affected, but almost no one talks about the animals in the ocean. boundary. Though, the gradual extinction of marine plankton such as ammonite began well before the K-T boundary. Extinction is a natural part of life, and because of that, scientists have been able to study some extinction patterns. The definition of extinction is: extinction is the disappearance of an entire species. Also, most scientists have concluded that extinction is the ultimate fate of all species. Extinctions have happened continuously throughout the history of life.
There are many major extinctions that have happened throughout the history of our earth, but the K-T extinction event is the most well known. A lesser well known extinction event is the P-T extinction event, and this event was far more severe and a violent extinction than the K-T extinction event. Extinctions are not an unusual event, and species regularly disappear through extinction. Nearly all animal and plant species that have lived on earth from the K-T extinction event are now extinct. The rate of extinction is fairly steady, sometimes it spikes in occasional mass extinction events.
The animals that survived the K-T extinction event were omnivores, insectivores and carrion eaters. At the end of the Cretaceous Period, there were almost no herbivores or carnivores. Evidence suggests that the herbivores died out when the plants that the animals and food chain depended on died because of all of the fore mentioned events that occurred because of said impact event. After the herbivores died, the carnivores followed after, such as the Tyrannosaurus Rex, and its relatives, and enemies. The mammals and birds that survived fed on insects and such.
Scientists think that these animals survived ecause they ate non-living organic material, and this contributed to their survival and adaptation. All of the animals that survived the impact, or started surviving went through natural selection. Natural selection is what causes evolution, and chooses who stays on earth, and who must go extinct. For example, the dinosaurs couldn’t evolve fast enough to survive the catastrophe, and so natural selection got rid of them. The two main mechanisms that produce evolution are natural selection and genetic drift. Natural selection favors genes that aid survival and reproduction.
Genetic drift is a random change in the frequency of alleles, cause by a random sampling of a generation’s genes during reproduction. The importance of natural selection and genetic drift vary depending on the strength of the selection and the effective population size. Effective population is the number of individuals in a species capable of breeding, and passing on their genes. Remember: natural selection dominates in large populations, and genetic drift dominates in small populations. All of this evidence proves that the extinction of the dinosaurs, in some way shape r form, led to humans evolving.
If the impact event had not occurred, would there be some other dominant species? Of course. If nothing else, genetic drift and natural selection prove that life will always be striving for the top dog spot on the food chain. Luckily for us humans, because evolution took a turn for the worse for the dinosaurs, it took a turn for the better for us. Its sad that such wonderful creatures had to go extinct, but whether we want to believe it or not, its better for us if they were dead. Many people wish that dinosaurs could be alive today, and the book Jurassic Park by
Michael Crichton is evidence of some of the media wishing this to be true. This whole gaining more momentum and ended up with us. I don’t know if the snowball stopped, but I doubt it. Even now, humans are evolving, slowly, but surely. Personally, I believe that without the Chicxulub Crater crashing into planet Earth, and blocking photosynthesis and such, we as humans would not have formed as life beings. The Cretaceous Tertiary Extinction event occurred 65. 5 million years ago, and was a geologically short period of time. It was known as the K-T extinction event, and has since become famous.
The event is associated with the K-T boundary, which is a thin band of sedimentation found in various parts of the world. This was a large scaled mass extinction event, and may have been caused by one or more catastrophes. Evolution occurred once organisms were formed. Right now scientists believe that complex life came from simple chemical reactions. It is unclear how this occurred, and they have no explanation for it. Some of the theories for dinosaur extinction was an impact event, the Deccan Traps, a multiple impact event, and multiple causes. The Campanian Rock formations prove that it was an unnatural extinction.
It shows many diverse species of dinosaurs before the K-T boundary, meaning that food was plentiful prior to the mass extinction. Showing, that it wasn’t a slow death the dinosaurs had, it was relatively quick. This event, though, is not an unusual event. Scientists have been studying extinction patterns for decades. Species regularly disappear through extinction. Mammals and birds survived because of genetic drift and natural selection, as they were able to adapt, and the dinosaurs were not. This concludes my science paper, proving that dinosaurs did in fact affect evolution, and human life on Earth.