![]() Males of Lucy’s species were probably closer to 150 cm tall (McHenry, 1991). They used mathematical formulas that relate femur length to stature to predict that Lucy stood approximately 104 to 106 centimeters (cm) tall (Feldesman & Lundy, 1988 Jungers, 1988 McHenry, 1991). Later, scientists estimated Lucy’s height based on the length of her femur, even though the end of her femur had been crushed prior to complete fossilization. 288 were those of a female (see Scott & Stroik, 2006, for a discussion of the alternative models of sexual dimorphism in Lucy’s species). He knew that, like many living primates, hominins tended to be sexually dimorphic, meaning the males were bigger than the females therefore, it seemed clear that the relatively small bones recovered from A.L. He was knowledgeable about fossil hominin discoveries made by other researchers, in other parts of Africa, in decades prior to the Lucy discovery. Johanson hypothesized almost immediately that Lucy was a female because of her small size. Lucy’s skeleton comprises fossil fragments that are extremely similar in appearance. In addition, the color and appearance of fossils is determined, in part, by the minerals that were present in the deposits where the fossils formed and the type of weathering the fossils experienced, so a group of fossils that formed at different times in different deposits would likely be different colors and show different signs of weathering. Instead, they found only enough bone fragments to compose one partial skeleton the probability that these fossilized bones are from more than one individual is therefore very low. This is not what the Hadar team discovered. If, for example, the Hadar field team had found fragments of three femora or had discovered two mandibles, they would have known immediately that the remains of multiple individuals were eroding out of the sediments. If the fossil fragments belonged to more than one individual, we would expect to find more fossilized bones than could possibly belong to a single skeleton. Johanson and Gray carefully scanned the ground and were delighted to discover many more fossilized bone fragments, including parts of a cranium, mandible, ribs, pelvis, thighs, feet, and more (Figure 1). Lucy’s broken ulna was protruding from the sediments and Johanson could tell by its shape and size that it definitely belonged to a primate and could very possibly be the fossilized remains of a hominin. One could say Lucy’s discovery is a “funny bone story.” The first fragment of Lucy’s skeleton that Johanson spotted was the elbow region of her ulna (when you bump the ulnar nerve in your elbow, it presses against your humerus and you get that tingly, “funny bone” feeling). Johanson was optimistic about what the team might find and he became more expectant when his Ethiopian colleague, Alemayehu Asfaw, discovered some hominin jaws near their Hadar camp (Johanson & Edey, 1981 Johanson and Wong, 2009). He had traveled to Ethiopia before, in 1972, on a reconnaissance trip to inspect the geological formations and fossiliferous deposits of the Afar region of Ethiopia, and again in 1973, when he made his first hominin discovery at Hadar-a knee joint. and professor of anthropology in Cleveland, Ohio. In male gorillas and orangutans (and some species of fossil hominin), in which very large chewing muscles are anchored to a relatively small cranial vault, the right and left superior temporal lines not only converge at the midline of the top of the cranial vault (along the sagittal suture), but also require the development of a sagittal crest to provide sufficient attachment area for the temporalis muscles.In 1974, Johanson was 31 years old, a newly-minted Ph.D. In apes the superior extent of the temporalis muscles is positioned higher on the cranial vault (because brain size is smaller, and the muscles of mastication are larger than those found in humans), such that the right- and left-side superior temporal lines approach one another at midline. In humans, who have large brains (and hence large cranial vaults) relative to their body size, the temporal muscles occupy a position on the lateral walls of the cranial vault, and extend only about halfway up the vault surface. The crest provides a surface for the attachment of the large chewing muscle, temporalis. Sagittal crests are rare in adult male chimpanzees and female gorillas, and are unknown in female chimpanzees, female orangutans, and humans and bonobos of both sexes (and are also absent in juveniles of all species). The sagittal crest is a prominent ridge of bone that projects superiorly (upwards) from the cranial vault along its midline, most commonly seen in adult male gorillas and orangutans.
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