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Essay On Shark Teeth

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Mariah Ross Period 8 Adaption of teeth among sharks Shark teeth often change size and shape based on its position in the shark’s mouth, whether it’s from the upper or lower jaw, and the age, sex, and species of the shark it came from. Shark teeth are produced and shed serially moving forward as though they are on a conveyor belt. With this replacement system, one shark can produce, use, and shed as many as 6,000 teeth each year. If a shark tooth is well preserved it offers the scientist a number of points that can be used to identify the species and the basic taxonomic group of shark it came from. However a great number of shark tooth fossils aren’t well preserved and are often times worn down to the point being smooth and featureless, making them all but useless in the identification process. Early Fossil Shark Teeth and consequent evolution The earliest known fossil shark teeth are those of Leonodus (left) dating back some 400 million years. Their overall crown shape vaguely resembles that of fossilized Xenacanthus (right) teeth, possibly indicating that these early sharks were related. Their roots, however, are quite different, suggesting that Leonodus and Xenacanthus may have evolved similar crowns as an adaptation to feeding on similar prey rather than due to shared ancestry. No one is sure which group of sharks evolved in to their modern counterparts, but until recently many scientists believed that it was the Hybodonts. However, paleoichthyologist John G. Maisey’s extensive studies of fossil and modern sharks, causes some belief that the hybodonts were a side-branch of shark evolution that did not give rise to any group of modern shark. Maisey has proposed that a genus known as Synechodus may be more closely related to ... ... middle of paper ... ...ark can eat 1% to 10% of its overall body weight per week. Many shark species swallow their food whole without any form of chewing. While some sharks are probably not very selective feeders, certain sharks eat some foods more than others. For example, hammerhead sharks are known to eat stingrays; bull sharks eat other sharks; and smooth dogfish eat crabs and lobsters. Tiger sharks feed opportunistically on both live food and carrion. Their prey includes bony fishes, other sharks, marine mammals, seabirds, and invertebrates. How Sharks Work by Tom Harris, http://animals.howstuffworks.com/fish/sharks/shark4.htm Martin, R. Aidan. 2003. Copyright and Usage Policy. World Wide Web Publication, www.elasmo-research.org/copyright.htm http://seaworld.org/en/animal-info/animal-infobooks/sharks-and-rays/diet-and-eating-habits/ NO AUTHOR LISTED, DIET AND EATING HABITS
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