Evidence for Evoluti15

Evidence for Evoluti15 - whale hunted in shallow mangrove...

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Evidence for Evolution Whale with legs This is my fourth posting in my "evidence for evolution" series. This will be a short one. It's a short, gee-whiz paper from Science. In my next post (tomorrow, maybe) I'll explain a paper in Nature in which the authors sequenced DNA from a 17-20 MY old magnolia leaf. I'll tell what they found (it's cool) and how they did it (also cool). In the July 13, 1990 issue of science, Gingerich et. al. report on an interesting fossil found in Egypt. It is a whale with feet. The skeleton is of the species Basilosaurus isis . This whale lived in the Eocene period (in Egypt (then under water obviously)). Current cetacea (whales), as you are no doubt aware, do not have external hind limbs. But whales, which are mammals, evolved from terrestrial mammals. This fossil, therefore, is a link between the two. The skeleton they show is long (16 m) and serpentine. The authors believe this
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Unformatted text preview: whale hunted in shallow mangrove or seagrass habitat. It's hind limb has a short femur and a slightly shorter fibula and tibia. It has no thumb and a greatly reduced second digit. The other three fingers are quite long (relatively). In short, another variation of the basic mammalian leg. The authors speculate that the limbs were tucked in close to the body while the whale was swimming (and the topography of the bones suggest that they are correct). Furthermore, they go on to speculate that the limbs served as a copulatory guide for the whale. The one thing I didn't like about the paper was a lack of actual photographs of the specimen. They gave graphs and schematic diagrams of all the salient features, but no photos. I would think that in a paper of this nature, a picture would have been worth a thousand words. Maybe they are working on the reconstruction and want to complete it before display....
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This note was uploaded on 11/14/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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