. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. VERTEBRAL CENTRUM HYLOCHOERUS d = ran. DERMAL SCUTE CROCODYLUS EQUUS MOLAR Figure 6. The hydraulic equivalents of different recent bones, as determined by settling velocity experiments. The equivalent quartz grain sizes were calculated using the method shown on Page 492 and the data given in Table 3. Density variation in the bones is the primary factor causing the variability of the hydraulically equiva- lent grain sizes. (Bones and grains are drawn to correct relative sizes.) variation in bone-quartz equivalence
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. VERTEBRAL CENTRUM HYLOCHOERUS d = ran. DERMAL SCUTE CROCODYLUS EQUUS MOLAR Figure 6. The hydraulic equivalents of different recent bones, as determined by settling velocity experiments. The equivalent quartz grain sizes were calculated using the method shown on Page 492 and the data given in Table 3. Density variation in the bones is the primary factor causing the variability of the hydraulically equiva- lent grain sizes. (Bones and grains are drawn to correct relative sizes.) variation in bone-quartz equivalence is shown graphically in Figure 6. It is obvious that the lighter bones, such as the vertebral centrum, and bones with high surface area to volume ratios, such as the crocodile scute, will be more easily transported than the heavier and more spherical bones. The quartz equivalents agree well with the evi- dence for differential dispersal potentials of these bones from Voorhies' (1969) flume study. Combined evidence from the settling velocity and flume experiments provide the general background necessary for predict- ing the behavior of bones in transport situ- ations. More work is needed, however, since in specific cases, the hydraulic equiv- alence and flume data do not agree. The sheep scapula, for instance, has a relatively large quartz equivalent ( mm), which is inconsistent with its high potential for dispersal in Voorhies Groups I/II. The Hydraulic Equivalents of Fossil Bones It would be useful to be able to predict, in general, the original quartz equivalent of any given fossil bone. Such data could then be compared with matrix grain sizes associ- ated with the fossils. The quartz equivalent of any object can be calculated if its density and volume are known, and if shape can be disregarded or corrected for. The basic equation is: d„ = (p„-i) Nominal diameter of the d„ pb bone = \ X Volume Bone densitv I. Please note that these images are extracted
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