Contributing Factors to Dinosaur’s Extinction
Sixty-five million years ago, scientist believed that there was an event that changed the face of the earth and wiped more than half of all living creatures on the planet. The phenomenon brought major and abrupt changes that resulted to mass extinction of 75% to 90% of life forms on earth in which many of them had vanished and fossil record of their existence never again seen (Fortey, 1999). Earth was in a period of chaos as continents were thrust and pushed into new locations, ocean ridges particularly the Atlantic and the Indian Ocean displayed a great deal of expansion. Formations of major mountains were also observed in the process while wide spread volcanic eruptions are being experienced. As a result of these occurrences, continents sunk deep with in the seas while other rose (Fortey, 1999). Earth’s oceans and atmosphere was in disarray and there were massive evidence that they were in a state of disorder. Great hurricanes, storms and tornadoes were also in the forefront of destruction as continental weathering was happening at a very quick rate. The atmosphere showed massive chemical changes and temperature and climate were changing. With the abrupt transformation and earth changing phenomena that were taking place, the different life forms on earth were unable to adapt. Dinosaurs which were roaming the earth gradually die. The Late Cretaceous period proved to be the last for the dinosaurs as they become extinct brought by the catastrophic incidents (Caldeira, 1999).
In explaining what could have lead to these events that eventually yield dinosaurs extinction, scientist devised different theories that they feel have contributed to the events that have transpired (Mullen, 2004). Although, some theories poses dilemma and further questions arise from explaining these theories, they are supported by facts and evidences (Than, 2006).
The Impact Theory is the most popular explanation of how dinosaurs came into their extinction (Alvarez, 1997). It is a general theory used to explain how mass extinctions have occurred. With in this theory are the contributing factors that led to the death of dinosaurs. Scientists proposed that either an asteroid or a comet came in contact with the earth’s atmosphere, shattering the planet and igniting a huge blast (DeHaan, 1997). The huge ball of fire smashes the earth’s hydrosphere creating big splash of water that resulted to continents sinking to the bottom of the oceans as flash floods enveloped the continents (MacLeod, 1998). Debris of rocks and dusts were also thrown in different directions as part of the asteroid hit the ground. Aside from the instant death that some dinosaurs experienced upon the comet or asteroid impact on earth, death were also brought to their species as dust and other particles cover the earth for a long period of time. Sun rays were blocked from entering the atmosphere as particles enveloped the planet due to the huge impact of the collision that throws different dust and rock particles into the atmosphere. Without the sun there was no source of principal energy (Bambach, 2004). With the black darkness blanketing the whole planet, plants eventually wither and die. Starvation then creeps as vegetations that serve as foods for the dinosaurs became scarce (Alvarez, 1997). Food shortage was experienced all over the planet followed by extreme coldness that envelops the earth. With little food and coldness the surrounded the planet, mass extinction of different animal which included the dinosaurs was inevitable. After the dusts and smoke that screened sunlight off the planet had subsided, greenhouse effect heated the earth further eliminating dinosaurs which may have survived during the close of the cretaceous period (McLean, 1995). The vast amount of iridium, a metal that is abundant only on the Earth’s interior but is common among asteroids and meteors, which is found on sedimentary deposits during Cretaceous period supports the impact theory (Alvarez, 1997). Further the observed drop then rise of temperature also validated this belief.
Another theory that scientist used to explain mass extinctions is the volcanic theory. Just like the impact theory it explains that extinction of dinosaurs is brought by the darkness and coldness that envelopes the planet that resulted to sun rays failing to reach the earth. The changes in weather and climate are brought by the massive and continuous volcanic activities around the planet (O’Keefe, 1989) . It explains that environmental changes that are caused by vast eruption of volcanoes are the major reasons why dinosaurs around the planet especially in regions situated in mid-latitudes became extinct.
Scientist also looked into radiation as contributing factors that lead to mass extinction of dinosaurs. Being exposed to radiation leads to mutation. Experts believed that radiation which could have come from exploding super nova and super solar flare near the earth helped alter genetic structure of several species. Due to the radiation which was absorbed by the dinosaurs mutation had occurred. As a result of these mutations, new species was produced. Little changes at the genetic level of composition and structure are proven to likely create new specie or stir up extinction process (Bambach, 2004). They have shown that extinction could have been caused by failed mutation that leads to the death of the great animals. Furthermore, radiation has resulted to poisoning that eventually killed different species of animals especially the dinosaurs.
Scientists also disclosed that extinction of dinosaur could have also been started from the dinosaurs themselves. In examining egg shells of the dinosaurs they have found out that older layers of shells which explorers have discovered are thicker compare to the newer shells. Shell thickness of older eggs are measured to be approximately to be 0.1 inch , compared to egg shells of the late Cretaceous period which is 0.04 (Fortey, 1999). Experts also noted that newer eggs have poor coating, as result embryos that are contained with in the egg could not properly utilized the nutrients such as calcium which are needed to support their skeletons and proteins which are necessary for muscle growth development and other elements which supposedly will nourished them. Embryos then become unhealthy and became vulnerable with the presence of harsh weather and atmospheric conditions. Embryos could even die since shells which are aimed to protect them from dehydration and even predation would be incapable. Therefore large numbers of dinosaurs have died even during their infancy period. As a result their number depreciates even during a short period of time. Scientists explain that thin shells among eggs are caused by the cold fronts in the atmosphere and the presence of toxic components in the environment. They are results of DNA changes among the dinosaurs due to variation of hormones they secret. They also added, that presence of thin shells in eggs indicates high and increase mutation.
Increased in the amount of carbon dioxide in the earth’s atmosphere was also viewed as a major contributor in egg shells thinning. Together with selenium, the increased in amount of these two components to the atmosphere proved to be fatal for the dinosaurs. With the abrupt changes in the temperature, dinosaur’s embryo development was also affected as cold weather inhibits their development which in turn resulted to reduction of dinosaurs. The problem was coupled by the fact that dinosaurs are cold blooded (Than, 2006). As a member of cold blooded species of animals, they found it hard to adapt to changing weather patterns. Thus a slight change from cold to hot then hot to cold would make this gigantic animals uneasy.
Their size, also poses great disadvantage to them since they are unable to hibernate due to these feature. Thus, they are unable to control and check their body temperature to the appropriate temperature that would suit them. This will then bring out the topic of competition among other animals as a cause of their extinction. The emergence of mammals and their invasion of different parts of the world could have been major reasons of the extinction. Unlike the dinosaurs, mammals are warm blooded. They are able to adapt to the slightest and most extreme climate conditions that are presented to them. They are able to endure the stress that could be imposed to them the extreme by the varying weather condition such as the coldness that had engulfed the earth. With the famine that was being experienced by the animals due to overpopulation fierce competition and battle for survival was existing and with the earth’s condition favoring the mammals, dinosaurs had lost the battle to survive. It was also believed that predation from mammals which eat dinosaur’s eggs and young ones contribute to their extinction as what was supposed to be new generations of dinosaurs apparently have been eliminated.
It is also important to note how genetics of dinosaurs also contributed to the mass extinction of their species. In genetics perspective it is necessary to discuss the activity that their pituitary glands were engaged with. Over activity of their pituitary glands resulted to dinosaur’s increase in physical size. Bones and cartilage started to develop massively and grew relatively large as their pituitary gland continues in secreting growth hormones. With their abnormality in size efficiency and movement of dinosaurs were hinder and affected. Pituitary glands start to malfunction and overgrowth of horns and other body parts proved to be detrimental to their cause. Then, these traits were passed on to their child and to their children’s child which eventually affect the dinosaur’s population as they found it hard to adapt to the environment with their new frame.
Mass extinction of Dinosaurs which believed to have happened during the late Cretaceous Period can be attributed to different factors. In their extinction, the earth’s environment played the most prominent role. The different theories that scientist have made with regards to dinosaur’s extinction all are mainly based on the facelifts that were encountered by the planet. The abrupt changed in the earth’s atmosphere that changed the planet’s climate blanketing it in extreme coldness affected the dinosaurs as they failed to adapt with this condition. The effect extended up to the embryos they produced that may have quickened the rate of their extinction. Furthermore, plants were unable to photosynthesize that result to worldwide starvation. Massive volcanic eruptions, the continuous folding of mountains and movement of continents and expanding of oceans ridges all have their share in the extinction as dinosaurs failed to integrate with the continuous changing the earth was subjected and unable to protect themselves from the harmful situations presented to them. However, the extinction is not only prompted by their environment as genetics also contributed. Mutation caused by radiation gave birth to new species, while failed mutations eventually results to extinction.
References
Alvarez, W (1997). T. Rex and the Crater of Doom. Princeton University Press
Bambach, R.K. (2004). Origination, extinction, and mass depletions of marine diversity. Paleobiology
Caldeira, K. G. (1990). Deccan Volcanism, Greenhouse Warming and the Cretaceous/ Tertiary Boundary. Geological Society of America.
DeHaan, J. D. (1997).Kirk’s Fire Investigation. Upper Saddle River, N.J.: Prentice-Hall.
Fortey, R (1999). Life: A Natural History of the First Four Billion Years of Life on Earth. Vintage.
MacLeod, N (1998). Impacts and marine invertebrate extinctions. Geological Society
McLean, D (1995). The Deccan Traps Volcanism-Greenhouse Dinosaur Extinction Theory. Mullen, L (October 13, 2004). Debating the Dinosaur Extinction. Astrobiology Magazine
O’Keefe, J. D., and Aherns, T. J. (1989). Impact Production of CO2 by the Bolide and the Resultant Heating of the Earth. Nature.
Than, K. (2006). Scientists Debate Dinosaur Demise. Live Science.
University of Vermont
