Discovery of New Tiktaalik Roseae Fossils Reveals Key Link in Evolution of Hind Limbs
Ronak Shah1/14/14
http://www.sciencedaily.com/releases/2014/01/140113154211.htm
Author: University of Chicago Medical Center
Published: Jan 13 2014
Summary:
Recently the back part of the Tikaalik Roseae was discovered. The Tikaalik Roseae is a fish that resembles a fish/crocodile mix which is 325 million years old. After this back part of the body, scientists found what is the transitional species between fish and the first legged animals. A good analogy would be going from a 2 wheel drive in fish to a 4 wheel drive on land. A pelvic bone of the fish's was for the first time discovered along with "enhanced hind fins" that seem very similar to the first hind legs. The pelvis is the most interesting part. It is comparable to the pelvis of the first tetrapods and has, like them, a ball and hip socket. It was nearly identical size. Though no hind legs were found the hind limbs were just as complex and strong as the animals fore fins. Scientists say it is clearly possible the fish used the hind fins to walk on the ocean floor. This fish also contains a primitive form of a lung, though scientists think it was not used. It is a great step in understanding how the first sea based eukaryptes, started to walk.
Connection:
This article connects to our most recent unit on evolution. We learned about how natural selection makes it so only the organisms in a population best suited to survive pass down more gametes that those who don't. We also learned that if their is an open niche in the environment, it is common for an organism to evolve until it can fill that niche and get all resources and food that come with it. This relates to the article because if the hind limbs of the Tikaalik Roseae's ancestors allowed to walk on the ocean floor and get food, it would have been the best allele constantly getting stronger and more common and soon after, becoming strong enough to walk out onto the land and fill that niche.
Citation:
University of Chicago Medical Center. "Discovery of new Tiktaalik roseae fossils reveals key link in evolution of
hind limbs." ScienceDaily, 13 Jan. 2014. Web. 14 Jan. 2014.
The article talks about a preexisting theory of vertebrates developing mobile hind appendages only after they transitioned to land. Is there any evidence to support this theory, and how does this new discovery affect other theories of "the missing-link"?
ReplyDeleteThe theory i found states certain kinds of fish moved into the shallower and shallower areas to escape predators, and in the shallows, the legs needed to develop stronger for an easier way to move around. Darwins theory of Nat selection says that orgs with stronger and stronger legs would have reproduced better. The only problem with this theory is that scientists could not think of a fish having a lung but his changed when they found this fish. The evidence is scientists found fish fossils with stronger hind fins where the shallows would have been. The real legs developed after they were out of the water. This is different than other theories because they could not think of fish transitioning with lungs so the previous land orgs like algaea developed.
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