Bio Lab - Anuja Oza Anouck Champsour Angela Hsu Stephen...

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Anuja Oza, Anouck Champsour, Angela Hsu, Stephen Wilson 4/9/08 Macroevolution of the Horse 1. What do your results say about the timing of adaptive radiation in horses relative to this change in plants? Grasslands were found to become widespread approximately 24 million years ago, or about when Parahippus first started showing up. Parahippus was the first taxa to have a postorbital bone, which protects the eye from the temporalis muscle that controls jaw motion. The temporalis muscle began working much harder when browsers turned into grazers because of the low-quality grass they must chew. The next taxa to show up was Me rychippus B 19 million years ago, which also happened to be the first with a square jaw, a characteristic of grazers. 2. When did horses become adapted to grasslands? The final adaptation horses took toward become grassland grazers occurred 15 million years ago when the taxa Calippus showed up with one toe, instead of the three toes that all the prior taxa had. This adaptation allowed for faster movement through the open areas of grasslands to run from predators, because less toes equal less weight, which in turn equals faster movement with less energy. So the
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Bio Lab - Anuja Oza Anouck Champsour Angela Hsu Stephen...

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