There once was a time when dinosaurs walked this earth. These magnificent beasts thrived on this planet for nearly 200 million years. They dominated the food chains, some through their size, and others thanks to their intelligence. So how is it that they all disappeared so suddenly? That is a question that has remained unanswered ever since it was first posed. In this research I shall look at the evidence and research which has aimed at answering this all important question. I chose this subject because, when I was little more than a toddler, I was fascinated by dinosaurs.
I’d ask my parents for all sorts of movies, books, figurines, anything to do with dinosaurs in fact. Although these ancient creatures fed my imagination for years, as I got older, my interest in them dwindled, but then, a few months ago I was given the opportunity to revive my interest in this long lost world and I knew that, somewhere in my project, these ancient beasts had to be mentioned. In addition, the question of what happened to make a whole species die out is a question that caught my interest as I got older.
Dinosaurs seemed to be so incredibly powerful and well adapted to their environment that their mass extinction is very puzzling. What is wonderful with a subject like this is that there is no clear cut answer. Nobody can say for sure how this mass extinction took place. The search is ever ongoing, and that is why it is possible that, in ten years time, what I have written here may no longer be valid. As I found out while gathering the required information I needed in order to write this research, this subject is slightly more science orientated than I first thought.
I must admit, at first, I had some difficulty with several pieces of information myself; therefore, I’ve attempted to make the more intellectually challenging parts more accessible. In doing so, I have grouped my research under 2 main chapters. The first part of my research is devoted to the different hypotheses concerning the extinction event and the catastrophic effects they would have had on our planet at the time. In addition to this, the evidence supporting these hypotheses is presented.
In the first part of this chapter, I develop how our impact hypothesis concerning this extinction event came into being as well what would have been the possible consequences of such an impact. Dominic Pharaoh 5A Promoter: Harriet Gibson 4 After this, I review a second hypothesis concerning important amounts of volcanism in what are currently known as the Indian Deccan Traps. This part explains what exactly these Deccan Traps are and how a massive range of volcanoes perpetually erupting over millions of years has stressed contemporary biodiversity.
In the third part of this chapter, I approach a third, not yet sufficiently corroborated hypothesis concerning possible multiple impacts as well as the idea of a combination of hypotheses. The second chapter consists in tackling the selectivity issue. In other words, trying to answer the question “Why is it that some species survived while others did not? ” As has often been the case with this research, you will find that, once again, we have bumped into a question where a definitive answer has yet to be established.
However, scientists have speculated and posed a few suggestions which are likely to be close enough to the truth. In this part I shall therefore present the possible reasons as to why it is that some species survived and others did not. In the second section of this chapter, I will once again attempt to tackle an unanswered question only this time concerning the dinosaurs themselves. “Were dinosaurs warm-blooded or cold-blooded? ” Finally, before concluding, I shall attempt to explain why it is that they went extinct. . Dominic Pharaoh 5A Promoter: Harriet Gibson 5
I would also like to thank both my parents and Harriet, my promoter, for their support with this project. Dominic Pharaoh 5A Promoter: Harriet Gibson 6 II. The impact theory and the alternative hypotheses A. The impact or Alvarez theory A bit of history During the late 1970s, Walter Alvarez, alongside a group of Italian and American geologists, travelled to Gubbio (Italy) in order to study some sedimentary rocks dating back to the mid Cretaceous period. At first, Alvarez had no intention of studying dinosaur extinction however; he made a discovery that has led to the most promising theory yet concerning their demise.
During his time in Gubbio, Walter noticed a thin band of clay (1cm thick) separating the Cretaceous and Tertiary Periods and dating back to approximately 65 million years ago (around about when dinosaurs were known to have gone extinct). Fossilised plankton is abundant below this band of clay whereas, just above it, these fossils completely disappear and are replaced by a far scarcer and smaller type of plankton. . Geological time line -> http://caveofthemounds. com/geotimeline. htm site visited on the 23/02/12 Dominic Pharaoh 5A Promoter:
Harriet Gibson 7 Following this discovery of his, Walter returned to the United States with a specimen of rock which included all three layers present at the Cretaceous-Tertiary boundary (aka the K-T boundary) in order to show his father (Nobel Prize winning physicist, Luis Alvarez). They later discovered that the layer of clay separating these two geological periods contained and exceptionally high concentration of iridium. This metal is extremely rare on our planet however; it is abundant in asteroids.
This led the two scientists to believe that the K-T extinction event may have been caused by the collision of an asteroid with the earth, an asteroid as massive as 10-13 kilometres in diameter. Of course, this new “impact hypothesis” was utterly shocking and novel to the scientific community. It over-turned many of the existing explanations and was thoroughly rejected by a large majority of the scientists at the time. Even today, the extinction of the dinosaurs remains an unsolved mystery although this new line of research has proved extremely promising. 1 What would have happened if an asteroid that size had hit our planet?
Speculation varies as to the outcome of such an impact but, in any case, the consequences would have been devastating. Firstly, any living being within several hundred, or maybe thousands, of kilometres surrounding the blast site will have been almost certainly annihilated. Secondly, seeing as the impact seemingly took place on the tip of the Yucatan Peninsula (Mexico), a massive tsunami, far bigger than anything ever experienced by man, would have dispersed in every direction, destroying animals and vegetation alike in both the ocean and for miles inland.
Some computer modules suggest that the initial wave height may have reached as much a couple of kilometres. It is equally posited that temperatures will have risen dramatically after the impact and that flaming balls of ejected rock will have created wild fires all around the globe. It is even said that some of these flaming projectiles may have even left the earth’s atmosphere, attaining a sort of temporary orbit before falling back to earth, such was the force of the impact. 2 1