Alligators reveal how dinos survived low oxygen levels.Byline: ANI Washington, April 17 (ANI): Scientists have studied alligators to analyze what life may have been like for dinosaurs <onlyinclude> This list of dinosaurs is a comprehensive listing of all genera that have ever been included in the superorder Dinosauria, excluding class Aves (birds, both living and those known only from fossils) and purely vernacular terms. at low oxygen levels of 12 percent during pre-historic times. The scientists chose the alligator alligator, large aquatic reptile of the genus Alligator, in the same order as the crocodile. There are two species—a large type found in the S United States and a small type found in E China. Alligators differ from crocodiles in several ways. as a test subject for the study because they are believed to be the modern relatives of the dinosaurs. "We knew testing the effects of different oxygen levels would work with alligators because crocodilians have survived in their basic shape and form for 220 million years. They must be doing something right to have survived the oxygen fluctuations," said scientist Tomasz Owerkowicz. Choosing to start at the beginning of alligator development, the scientists decided to try incubating alligator eggs at different oxygen levels, to find out how the youngsters grew and developed. Receiving newly laid alligator eggs from Elsey at the Rockefeller Wildlife Refuge wildlife refuge, haven or sanctuary for animals; an area of land or of land and water set aside and maintained, usually by government or private organization, for the preservation and protection of one or more species of wildlife. , Owerkowicz divided the eggs into groups incubated at 12 percent (low) oxygen, 21 percent (normal) oxygen and 30 percent (high) oxygen, and waited to see what would happen. After almost 10 weeks of waiting, the eggs began hatching and Owerkowicz could see that there were no obvious differences between the alligators that developed in normal and high oxygen atmospheres. But, he was in for a shock when the low oxygen level hatchlings began to emerge. The tiny alligators' bellies were enormously swollen. They had failed to absorb all of the egg yolk yolk (yok) the stored nutrient of an oocyte or ovum. yolk n. The portion of the egg of an animal that consists of protein and fat from which the early embryo gets its main nourishment and of food supply, leaving them with huge yolk-distended bellies. In some casesm the bellies were so big that the animals' legs could not reach the ground, and the alligators had to sit around until they had burned off the yolk and could begin moving. Owerkowicz suspects that there was not enough oxygen for the developing embryos to consume the yolk. The low oxygen level youngsters' organs were much smaller too, all except the heart, which was relatively large, presumably pre·sum·a·ble adj. That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster. to maximize use of the youngsters' limited oxygen supplies. Next, Owerkowicz was curious to see how the alligators performed after 3 months in their respective atmospheres. When Owerkowicz checked the size of the 3 month old low oxygen youngsters' lungs, he could see that they had caught up with his expectations and were larger than those of the normal oxygen alligators. The alligators' lungs were enlarged to compensate for the low oxygen supply, allowing the alligators to increase their metabolic rates Noun 1. metabolic rate - rate of metabolism; the amount of energy expended in a give period basal metabolic rate, BMR - the rate at which heat is produced by an individual in a resting state , but not as much as the normal or high oxygen alligators. Owerkowicz admits that although his results can't tell us what life was like for his alligators' prehistoric pre·his·tor·ic also pre·his·tor·i·cal adj. 1. Of, relating to, or belonging to the era before recorded history. 2. Of or relating to a language before it is first recorded in writing. predecessors, it is clear that 'their growth and metabolic met·a·bol·ic adj. Of, relating to, or resulting from metabolism. Metabolic Refers to the chemical processes of an organ or organism. patterns would have been significantly different'. (ANI) Copyright 2009 Asian News International The Asian News International (ANI) agency provides multimedia news to China and 50 bureaus in India. It covers virtually all of South Asia since its foundation and presently claims, on its official website, to be the leading South Asia-wide news agency. (ANI) - All Rights Reserved. Provided by Syndigate.info an Albawaba.com company |
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