Hypotheses On the Origin of Birds
Since the advent of the theory of evolution the origin of birds has been a thriving topic in science. Many ideas and hypotheses have been presented, but only two stand today: that birds are descendents of ancient thecodont stem reptiles, and that birds are the direct descendents of a group of dinosaurs known as the coelurosaurs. Both hypotheses pose many interesting and insightful ideas based on information obtained from the fossil record. There is not enough evidence at this time to determine which hypothesis, if either, is right. Only more hard work by scientists will tell. Until then we have only speculation, but speculation based in observed evidence.
The origin of birds is one of the great mysteries in biology. Birds are dramatically different from all other living creatures. Feathers, toothless beaks, hollow bones, perching feet, wishbones, deep breastbones, and stump-like tailbones are only part of the combination of features that no other living animal has in common with them (Padian and Chiappe 1998).
Scientists have speculated on the evolutionary history of birds since shortly after Charles Darwin established his theory of evolution in On the Origin of Species (Padian and Chiappe 1998). One year later, in 1860, a solitary fossil feather of a bird was found dating back 150 million years. The next year a skeleton of an animal that had bird-like wings and feathers, but a very unbirdlike long, bony tail and toothed jaw, turned up in the same region. These finds became the first two specimens of Archaeopteryx lithographica, the most archaic known member of the birds, and sparked the immense interest in the evolution of birds and the search for their ancestors (Padian and Chiappe 1998...
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...y of Deinonychus antirrhopus, an unusual theropod from the Lower Cretaceous of Montana. 1969: Bulletin of the Peabody Museum of Natural History, Yale University 30: 1-165. In: Feduccia 1996: p 66.
Padian K, and Chiappe LM. The origin of birds and their flight. Sci Amer 1998; 278: 38-47.
Recer P. Fossils challenge the theory of dinosaur origin of birds. 2000: Available from:
http://www.canoe.ca/CNEWSScience0006/
23_dino.html. Accessed: Sept. 14, 2000.
Stokstad E. Feathers, or flight of fancy? Science 2000; 288:2124-5.
Tarsitano S, and Hecht MK. A reconsideration of the reptilian relationships of Archaeopteryx. 1980. Zoological Journal of the Linnean Society of London 69: 257-263. In: Feduccia 1996: p 70.
Unwin DM. Feathers, filaments and theropod dinosaurs. Nature 1998; 394:234-5.
Zhao X, and X Xu. The oldest coelurosaurian. Nature 1998; 394:234-5
The war was coming to a victorious conclusion for the Allies. Germany had fallen, and it was only a matter of time until Japan would fall as well. Secretary of War Henry L. Stimson was at the forefront of the American war effort, and saw atomic weaponry as a way out of the most monumental war ever. As discussed in Cabell Phillips’ book, The Truman Presidency: The History of a Triumphant Succession, Stimson was once quoted as saying that the atomic bomb has “more effect on human affairs than the theory of Copernicus and the Law of Gravity” (55). Stimson, a defendant of dropping the bomb on Japan, felt that the world would never be the same. If the world would change after using atomic weapons, could it possibly have changed for the better? One would think not. However, that person might be weary of the biased opinion of White House personnel. He or she should care more for the in depth analytical studies done by experts who know best as to why America should or should not have dropped the atomic bomb. As more and more evidence has been presented to researchers, expert opinion on whether or not the United States should have dropped the two atomic bombs on Hiroshima and Nagasaki has also changed. More and more researchers seem to feel that the atomic bomb should never have been used (Alperovitz 16). Despite several officials’ claims to enormous death estimations, an invasion of Japan would have cost fewer total lives. In addition, post atomic bomb repercussions that occurred, such as the Arms Race, were far too great a price to pay for the two atomic drops. However, possibly the most compelling argument is that Japan would have surrendered with or without the United States using the atomic bomb. In defiance of top...
Calyptorhynchus banksii, commonly known as the red-tailed black-cockatoo, is of the Family Cacatuidae (Cockatoos), which is a branch of the Order Psittaciformes. Red-tailed black-cockatoos are indigenous to Australia and can be found throughout the entire continent. Calyptorhynchus banksii is distinct in that there are five different subspecies: Calyptorhynchus banksii( C.b.) banksii, C.b. macrorohynchus, C.b. naso, C.b. graptogyne, and C.b. samueli (Del Hoyo et al., 1997). Differences in beak apparatus are one of the most prevalent variations observed within the subspecies. Throughout the paper an examination of evolutionary forces will explain the changes that have occurred in the beak apparatus of the red-tailed black-cockatoo.
The bombings of 1945 by the United States of America on Japan were very controversial events. Many historians believe these acts were aggressive and unnecessary. In addition, analysts argue that the U.S. should have used alternative methods instead of the bomb, but most do not realize the repercussions of these different tactics. On the contrary, the bomb was needed to ease tension quickly and effectively. Ultimately, the bomb proved more effective than any other method, and also proved to be a technique that is sufficient for America’s needs. The effort made by the U.S. to bomb Japan after their disapproval of the Potsdam Declaration was needed to end conflicts in the Pacific because of Japanese resistance, to save American lives, and to portray the U.S. as a nation of power and dominance.
People normally tend to assume that plants in the past vary in differences and traits compared to species that are present. People have the impression that the past species had diverse weather conditions and nature related incidents forcing them adapt and become different from others. In the book, Andrew Knight had the idea that the food that was available could have tampered with their genes. Reproduction could have something to do with species changing. With plants, minor situations could determine whether they disperse a seed. It happens quickly and changes the genes of the plant causing a new formation that is disseminated through plant. Reproduction inheritance of genes is an important aspect when trying to determine ancestor’s life. By studying these pigeons, Darwin decides that all pigeons have originated from the rock-pigeon. Many people believe that pigeons have descended from a numerous amount of species and birds. Pigeons mate for life and by doing so the breeds are kept together and have markings in same areas of body. They mold into different species as years have passed because of the natural selection or an idea that Charles called unknown selection.
Bard, Mitchell G. The Complete Idiot's Guide to world War II, Macmillan Publishing, New York, New York, 1999
One of the most controversial decisions that have been made, in the history of the United States, was Harry Truman’s decision to drop atomic bombs on the two Japanese cities of Hiroshima and Nagasaki. The ever so controversial topic of the dropping of the atomic bombs has successfully driven people insane. People feel strongly that this decision was atrocious and unnecessary, while others believe the polar opposite, that it was completely necessary. Some historians argue that the human cost to the Japanese population can never justify the use of such weapons. Other historians see it from an optimistic perspective, that it would not have been moral if atomic weapons had not been used to end the war as quickly as possible. President Harry S.
Kuznick, Peter J. "The Decision to Risk the Future: Harry Truman, the Atomic Bomb and the Apocalyptic Narrative.” JapanFocus. The Asia-Pacific Journal: Japan Focus, 9 Dec. 2013. Web. 09 Jan. 2014.
Jonathan Weiner, The Beak of the Finch: A Story of Evolution in Our Time. New York:
Fossil evidence suggests that the Cathartid (New World) vultures have been around for quite some time with two fossil species dated from the early Oligocene (about 35 million years ago). During the Pliocene and Pleistocene (about 2 million years ago) th...
Horsey addresses the argument that gay marriage would ruin the sanctity of marriage. The cartoon was made around April, at the same time as Supreme Court rulings on the Defense Of Marriage Act and Proposition 8. By addressing the argument, Horsey is using pathos to allow the reader to make their own conclusion that this claim is incorrect. Rather than stating right out that the claim is incorrect, he proves this to the reader through ironic and comedic imagery and still allows the reader to come to their own conclusion. Horsey places his comic in a 24-hour Las Vegas chapel to prove his point, pointing out a major flaw in the anti-gay argument, which is that not all current heterosexual marriage is sacred. Rather, a large portion of the weddings that take place in Las Vegas are down under the influence of alcohol, not love, like with the intoxicated couple waiting in the window in the cartoon. He also promotes the idea that spontaneous Las V...
del Hoyo, Josep, Andrew Elliott and Jordi Sargatal. Handbook of the Birds of the World. Vol 1, Ostrich to Ducks. Barcelona: Lynx Edicions, 1992.
Dill’s difficult life is at home with his family. We learn early on in the story that Dill is sent to live with his Aunt in Maycomb County for every summer. We also discovered that Dill does not have a father, when Dill replies to Scout’s question about a father,”I haven’t got one”(8), is what he answers. Having no father and having your mother send you away every year can harshly impact a child’s life. Even though Dill shows no noticeable sign of having a poor family life, we know that something catastrophic might happen to Dill in the long run if no one does anything to fix Dill’s problem.
Nuddes and Dyke's analysis of the Archaeopteryx and Confuciusornis wing fossils concluded that their wings are too thin and weak to take flight ( 2010). According to Nuddes and Dyke, they would need to have solid primary feathers for them to be able to fly (2010). The fossils of the Archaeopteryx and Confusciusornis show rachises that are too narrow to fly. Also, their wings show the likelihood to fail by buckling if they attempt flight ( Nuddes and Dyke, 2010). Since the two species have similar wing feathers as the modern bird, the only way they could fly is if their wings serve as a parachute ( Nuddes and Dyke, 2010). In other words, they would have been gliders ( Nuddes and Dyke, 2010). Even with that theory, these birds are still weak flyers ( Nuddes and Dyke, 2010). Palaeontologist had found their fossils in lake sediments and oceans ( Nuddes and Dyke,
The profession of architecture, the possible career as an architect, taking steps to gain a position and education as well as the set growth and prospects of this profession. According to Lee W. Waldrep (2010), author of the book Becoming a Architect “A Guide to Careers in Design, an architect is an imaginative person who designs a wide range of structures for buildings”(p. 2). These structures not only have to be aesthetically pleasing, but must also meet the safety requirements. Architects have to compete with other architects to attract customers by presenting designs. This process is generally based on building a reputation as an architect. Due to the nature and the amount of time devoted to designing, architects
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