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
Ceratopsians and Pachycephalosaurs are closely related in their characteristics. Ceratopsians processed a saddle-shaped boney frill that extended from the skull to the neck and typically had horns over the nose and eyes. The most popular was the triceratops, which could reach over 26 feet and weigh in excess of twelve metric tons. Their frills served as two major functions. It protected the vulnerable neck from being harmed. The second major function that the frill provided was due to the fact that the frill contained a network of blood vessels on its underside, which were used as a means to get rid of excess heat. The Pachycephalosaurs were considered to be bipedal. They were also found to have thick skulls, flattened bodies, and tail that were covered in an array of body rods. Pachycephalosaurs were thought to have been more than fifteen feet long and processed a skull that was surrounded by a rounded dome of solid bone. It was thought that they used their heads in combat or mating contests, but that was disproved fairly recently, which I will discuss later in the paper. Both Ceratopsians and Pachycephalosaurs were “bird-hipped” and both of these suborders contained a backwards pubic bone. Both were Marginocephilia, or “fringed heads”, which is one of three clads under the Orinthiscia order. They were also herbivore dinosaurs that inherited their fringe at the back of the skull from earlier ancestors.(2) Their classi...
Paul, Gregory S. (2002). "Looking for the True Bird Ancestor". Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds. Baltimore: Johns Hopkins University Press. pp. 171–224. ISBN 0-8018-6763-0.
Denotatively a bird is defined as a, Any of a class (Aves) of warm-blooded vertebrates distinguished by having the body more or less completely covered with feathers and the forelimbs modified as wings, often capable of flying. The authors/Glaspell’s strategic comparison of Mrs. Wright to a bird can be interpreted connotatively that she was a free,
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
The results of natural selection in Darwin 's finches and British Columbian sparrows change my view of species because every living animal changes to survive conditions that get in the way of normal life.
...(1995). The Beak of the Finch: A Story of Evolution in Our Time. Vintage Books: New York.
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.
Smith, Gene. "Lost Bird." American Heritage 47.2 (1996): 38. MAS Ultra - School Edition. EBSCO. Web. 6 Apr. 2015.
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...
Until recently, scientists believed the chances of finding a fossilized dinosaur heart were extremely slim. The heart belonged to a 66 million year old dinosaur found in Harding County in Northwestern South Dakota. The dinosaur, found in 1993, weighed over 650 pounds and was 13 feet long. The dinosaur was in fairly good condition with the exception of the left side of the skeleton. The small, plant-eating Thescelosaurus, nicknamed ‘Willo’ has been acquired by the North Carolina Museum of Natural Sciences. Thescelosaurus was an ornithischian, or "bird-hipped," dinosaur that lived in the latter stage of the Cretaceous period. This was approximately 1 million years before the end of the dinosaur era. Native to North America, its range extended from the northern United States up into Canada. Since using the 3-D software to reveal Willo's heart, scientists have also used it to create 3-D images of the fossil's skull, and of remains from other dinosaurs in the museum's collection. (Fisher, Paul)
The Burgess Shale Fauna is a fauna that was constructed based on a group of fossils that were initially found, in the Burgess Shale area in the Canadian Rockies (Gould, 1989). They are a very important group of fossils as “modern multicellular animals make their first unprotected appearance in the fossil record some 570 million years ago” through this group (Gould, 1989, pp. 24). Moreover the Burgess Shales are known to have preserved the soft parts of animals enabling us to get a better understanding of life at the time.
There were a few different themes in To Kill a Mockingbird one of which I believe would be the loss of innocence which I believe Dill represents in a odd way. Dill is a childish little boy who likes to play with Jem and Scout in fact early on in the book when the kids were acting Dill “played the character parts formally thrust upon Scout” (jem pg 8). Along with being a good friend and i nice guy Dill only came during the summer and loved to play with the kids he even ran away from home one summer when he couldn't come just to be with them. Dill never really loses his innocence and, I believe because of that he would make a good comparison to the kids at the end of the book after the attack. Along with being a good comparison Dill points out
...ocietal rules emphasizes the serious consequences of a scandalous. Additionally, Charles Smithson’s relationship with Sarah Woodruff has very notable consequences. Following his admittance to Ernestina, Mr. Freeman files a court order against Charles and specifically means Charles to remain a suitor for the rest of his life. As well, Charles is faced with another consequence following his kiss with Sarah; he feels that it is his duty to pay to put Sarah in a private asylum because of his attachment to her. Furthermore, individuals were faced with consequences after disregarding societal rules associated with sex and marriage.
When architects are put on this earth they have a dream; a dream to change the world in some way, shape, or form. If the architects receive fame and fortunes a result from their work, then that’s just a good perk. The project that they start to work on, integrates numerous elements in order to achieve the set goal. It should also be noted that every space is originally intended for a certain program, regardless of the space being flexible in use. The Paris Opera House professes, via its ceremonious and grand design, its function as a space suited for a gathering place of a “fashionable audience in an era of conspicuous wealth” (Kleiner 811) to enjoy art.