Linear enamel hypoplasia (LEH), a developmental defect of enamel, increases in frequency from pro... more Linear enamel hypoplasia (LEH), a developmental defect of enamel, increases in frequency from prosimian to monkey to lesser ape to great ape grades (Guatelli-Steinberg [2000] Am. J. Phys. Anthro- pol. 112:395–410, [2001] Evol. Anthropol. 10:138–151; Newell [1998] Ph.D. dissertation, Temple University). This taxonomic pattern in the distribution of LEH is closely related to maturation length across the primate order (Newell [1998] Ph.D. dissertation, Temple Univer- sity, [2000] Am. J. Phys. Anthropol. [Suppl.] 30:236). Longer maturation periods are associated with higher LEH frequencies; they appear to provide greater opportunity for defects to form. The present study explores the relationship between maturation length and LEH frequency within the Ceboidea. Because of its prolonged period of growth, Cebus is predicted to manifest LEH at a higher frequency than the more rapidly maturing ceboid genera. To test this hypothesis, two separate researchers (E.A.N. and D.G.-S.) examined LEH in non- overlapping museum series of ceboids. The results support the hypothesis: in 13 genera (n = 1,276), E.A.N. found that LEH frequencies ranged from 0% in Callice- bus, Cebuella, and Saimiri to 20% in Cebus. D.G.-S. found similar frequencies among five genera (n = 107), from 0% in Saimiri to 32% in Cebus. Thus, the broad pattern of LEH distribution evident across major taxonomic groups of primates is repeated within the Ceboidea. We also examined a related hypothesis linking the spacing of perikymata, which is influenced by enamel extension rates (Shellis [1998] J. Hum. Evol. 35:387– 400), to LEH. The most likely areas of tooth crowns to exhibit LEH in human teeth are those in which periky- mata are most closely spaced (Hillson and Bond [1997] Am. J. Phys. Anthropol. 104:89–103). We hypothesized that the longer-maturing Cebus, with its elevated LEH frequency, will also exhibit more closely spaced peri- kymata than other ceboids. Analysis of a small micro- scopic subsample (n = 8) lends limited support to this second hypothesis. Am J Phys Anthropol 131:252–260, 2006.
For centuries, cadaveric dissection has been the touchstone of anatomy education. It offers a med... more For centuries, cadaveric dissection has been the touchstone of anatomy education. It offers a medical student intimate access to his or her first patient. In contrast to idealized artisan anatomical models, it presents the natural variation of anatomy in fine detail. However, a new teaching construct has appeared recently in which artificial cadavers are manufactured through three-dimensional (3D) printing of patient specific radiological data sets. In this article, a simple powder based printer is made more versatile to manufacture hard bones, silicone muscles and perfusable blood vessels. The approach involves blending modern approaches (3D printing) with more ancient ones (casting and lost-wax techniques). These anatomically accurate models can augment the approach to anatomy teaching from dissection to synthesis of 3D-printed parts held together with embedded rare earth magnets. Vascular simulation is possible through application of pumps and artificial blood. The resulting arte...
Molar enamel thickness has played an important role in the taxonomic, phylogenetic, and dietary a... more Molar enamel thickness has played an important role in the taxonomic, phylogenetic, and dietary assessments of fossil primate teeth for nearly 90 years. Despite the frequency with which enamel thickness is discussed in paleoanthropological discourse, methods used to attain information about enamel thickness are destructive and record information from only a single plane of section. Such semidestructive planar methods limit sample sizes and ignore dimensional data that may be culled from the entire length of a tooth. In light of recently developed techniques to investigate enamel thickness in 3D and the frequent use of enamel thickness in dietary and phylogenetic interpretations of living and fossil primates, the study presented here aims to produce and make available to other researchers a database of 3D enamel thickness measurements of primate molars (n=182 molars). The 3D enamel thickness measurements reported here generally agree with 2D studies. Hominoids show a broad range of r...
Linear enamel hypoplasia (LEH), a developmental defect of enamel, increases in frequency from pro... more Linear enamel hypoplasia (LEH), a developmental defect of enamel, increases in frequency from prosimian to monkey to lesser ape to great ape grades (Guatelli-Steinberg [2000] Am. J. Phys. Anthro- pol. 112:395–410, [2001] Evol. Anthropol. 10:138–151; Newell [1998] Ph.D. dissertation, Temple University). This taxonomic pattern in the distribution of LEH is closely related to maturation length across the primate order (Newell [1998] Ph.D. dissertation, Temple Univer- sity, [2000] Am. J. Phys. Anthropol. [Suppl.] 30:236). Longer maturation periods are associated with higher LEH frequencies; they appear to provide greater opportunity for defects to form. The present study explores the relationship between maturation length and LEH frequency within the Ceboidea. Because of its prolonged period of growth, Cebus is predicted to manifest LEH at a higher frequency than the more rapidly maturing ceboid genera. To test this hypothesis, two separate researchers (E.A.N. and D.G.-S.) examined LEH in non- overlapping museum series of ceboids. The results support the hypothesis: in 13 genera (n = 1,276), E.A.N. found that LEH frequencies ranged from 0% in Callice- bus, Cebuella, and Saimiri to 20% in Cebus. D.G.-S. found similar frequencies among five genera (n = 107), from 0% in Saimiri to 32% in Cebus. Thus, the broad pattern of LEH distribution evident across major taxonomic groups of primates is repeated within the Ceboidea. We also examined a related hypothesis linking the spacing of perikymata, which is influenced by enamel extension rates (Shellis [1998] J. Hum. Evol. 35:387– 400), to LEH. The most likely areas of tooth crowns to exhibit LEH in human teeth are those in which periky- mata are most closely spaced (Hillson and Bond [1997] Am. J. Phys. Anthropol. 104:89–103). We hypothesized that the longer-maturing Cebus, with its elevated LEH frequency, will also exhibit more closely spaced peri- kymata than other ceboids. Analysis of a small micro- scopic subsample (n = 8) lends limited support to this second hypothesis. Am J Phys Anthropol 131:252–260, 2006.
For centuries, cadaveric dissection has been the touchstone of anatomy education. It offers a med... more For centuries, cadaveric dissection has been the touchstone of anatomy education. It offers a medical student intimate access to his or her first patient. In contrast to idealized artisan anatomical models, it presents the natural variation of anatomy in fine detail. However, a new teaching construct has appeared recently in which artificial cadavers are manufactured through three-dimensional (3D) printing of patient specific radiological data sets. In this article, a simple powder based printer is made more versatile to manufacture hard bones, silicone muscles and perfusable blood vessels. The approach involves blending modern approaches (3D printing) with more ancient ones (casting and lost-wax techniques). These anatomically accurate models can augment the approach to anatomy teaching from dissection to synthesis of 3D-printed parts held together with embedded rare earth magnets. Vascular simulation is possible through application of pumps and artificial blood. The resulting arte...
Molar enamel thickness has played an important role in the taxonomic, phylogenetic, and dietary a... more Molar enamel thickness has played an important role in the taxonomic, phylogenetic, and dietary assessments of fossil primate teeth for nearly 90 years. Despite the frequency with which enamel thickness is discussed in paleoanthropological discourse, methods used to attain information about enamel thickness are destructive and record information from only a single plane of section. Such semidestructive planar methods limit sample sizes and ignore dimensional data that may be culled from the entire length of a tooth. In light of recently developed techniques to investigate enamel thickness in 3D and the frequent use of enamel thickness in dietary and phylogenetic interpretations of living and fossil primates, the study presented here aims to produce and make available to other researchers a database of 3D enamel thickness measurements of primate molars (n=182 molars). The 3D enamel thickness measurements reported here generally agree with 2D studies. Hominoids show a broad range of r...
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