Essay on Physioanatomical Analysis of Australopithecus Afarensis

1573 Words Sep 21st, 2012 7 Pages
Haydee Munoz



15- April-2010

Physioanatomical Analysis of Australopithecus Afarensis

The first Australopithecus afarensis was found in 1974 by Don Johanson at Hadar in Ethiopia, Africa, and dates from about 3.9 to 3 million years ago. The very complete fossil is thought to be a female skeleton and it is called “Lucy” after a Beatles song. Because the skeleton is 40 percent complete, it facilitates a more accurate analysis in a broader sense. When comparing A. afarensis to a chimpanzee, a species with many traits that for hominins are considered primitive, and a modern human, it is concluded that the subject is very primitive, because it shows few developed traits.

The Lucy skeleton is female and it is
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First of all, the foramen magnum is located more to the center of the bottom of the skull, because of the humans’ more developed bipedalism. On the contrary, chimpanzees’ and A. afarensis’ foramen magnum is closer to the back edge of the bottom of the skull, which indicates less developed bipedalism. Another derived trait is that the human skull’s broader part is in the upper part of the skull and it is very rounded, while chimpanzees’ and A. afarensis skulls are broader in the bottom part of the skull and have a backward horizontally elongated skull, which suggests thicker muscles on the neck to hold a less centered head caused by a less developed bipedalism. One more human characteristic is a larger forehead and small brow ridges, but chimpanzees and A. afarensis have no foreheads and even though chimpanzees have thicker brow ridges, A. afarensis’ brow ridges are very thick also. Also, humans have a very flat postorbital constriction and even though A. afarensis has a flatter constriction than chimpanzees, their mandibles are still very far out. In addition, humans use tools and have a smoother diet, so they have a small zygomatic because they don’t need thick muscles for their mandibles. On the contrary, chimpanzees and A. afarensis have bigger zygomatics than humans because of their diet. Also, chimpanzees and A. afarensis have a bigger ascending ramus of mandible than humans.

The diet an organism follows influences

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