Fossil Discovery Impacts Theory on Evolution of Birds and Flight
In the past few decades, the hypothesis that birds evolved from dinosaurs has been widely accepted by many scientists because of fossil evidence. Now scientists are looking for ways to prove the origin of flight through extensive research of newly found fossils. The origin of flight has been debated between scientists for years, but without strong evidence, they have yet to come to a conclusion on the issue. The disagreement between the two sides is whether flight arose from creatures that lived in the trees or ones on the ground. A new discovery in western Liaoning, China shed some light on the debate and many scientists now conclude that flight evolved from creatures living in the trees.
Prior to this discovery, the debate over the origin of flight had no conclusive evidence and looked like it would not be solved. Arboreal theorists, who believed that flight arose in creatures that lived in the trees, supported their claim by observing “that flight is energetically more efficient at higher speeds (when more lift is generated),” (Prum). Therefore if the creatures began their flight from a higher elevation, they would create more speed as well as more lift enabling them to obtain flight. These theorists also argued that take-off from the ground is much more difficult than from the trees. They based this argument on the fact that flight stroke is continuous and would be much simpler from trees where flight would be level. These creatures could simply jump out of a tree and while falling would gain enough speed enabling them to fly.
Opposing the arboreal theorists were there cursorial theorists who felt flight evolved from la...
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... tree to gain enough speed to obtain flight. When Microraptor gui was discovered in 2000, this was an enormous gain for arboreal theorists. This well preserved creature provided evidence that flight evolved from tree-dwelling animals. Even though it is still not widely accepted, it gives us a new look on the issue and further research will certainly provide us will a solid conclusion.
Sources:
Prum, R. "Dinosaurs take to the air." 421. 23 January 2003: 323-324. 5 April 2004 <www.nature.com/nature>.
Xu, X., Zhou, Z., Wang, X., Kuang, X., Zhang, F., & Du, X. "Four-winged dinosaurs from China." 421. 23 January 2003: 335-340. 4 April 2004 <www.nature.com/nature>.
Zhou, Z., Barrett, P., & Hilton, J. "An exceptionally preserved Lower Cretaceous ecosystem." 421. 20 February 2003: 807-814. 4 April 2004 <www.nature.com/nature>.
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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.
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4. Pearson, Helen. “Asteroid let dinosaurs rule.” Nature 17 May 2012 Nature News Service/ Macmillan Magazines Ltd 2015
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