Pampush James D, Spradley Jackson P, Morse Paul E, Harrington Arianna R, Allen Kari L, Boyer Doug M, Kay Richard F
Department of Evolutionary Anthropology, Duke University, Durham, NC, USA.
Department of Anthropology, University of Florida, Gainesville, FL, USA.
Am J Phys Anthropol. 2016 Dec;161(4):705-721. doi: 10.1002/ajpa.23077. Epub 2016 Sep 16.
Three dental topography measurements: Dirichlet Normal Energy (DNE), Relief Index (RFI), and Orientation Patch Count Rotated (OPCR) are examined for their interaction with measures of wear, within and between upper and lower molars in Alouatta palliata. Potential inferences of the "dental sculpting" phenomenon are explored.
Fifteen occluding pairs of howling monkey first molars (15 upper, 15 lower) opportunistically collected from La Pacifica, Costa Rica, were selected to sample wear stages ranging from unworn to heavily worn as measured by the Dentine Exposure Ratio (DER). DNE, RFI, and OPCR were measured from three-dimensional surface reconstructions (PLY files) derived from high-resolution CT scans. Relationships among the variables were tested with regression analyses.
Upper molars have more cutting edges, exhibiting significantly higher DNE, but have significantly lower RFI values. However, the relationships among the measures are concordant across both sets of molars. DER and EDJL are curvilinearly related. DER is positively correlated with DNE, negatively correlated with RFI, and uncorrelated with OPCR. EDJL is not correlated with DNE, or RFI, but is positively correlated with OPCR among lower molars only.
The relationships among these metrics suggest that howling monkey teeth adaptively engage macrowear. DNE increases with wear in this sample presumably improving food breakdown. RFI is initially high but declines with wear, suggesting that the initially high RFI safeguards against dental senescence. OPCR values in howling monkey teeth do not show a clear relationship with wear changes.
研究三种牙齿形态测量指标：狄利克雷法向能量（DNE）、起伏指数（RFI）和旋转定向面片计数（OPCR），在蛛猴（Alouatta palliata）上下臼齿内部以及上下臼齿之间与磨损测量指标的相互作用。探讨“牙齿雕刻”现象的潜在推断。
从哥斯达黎加拉帕西菲卡机会性收集了15对嚎叫猴的第一臼齿（15颗上臼齿，15颗下臼齿），根据牙本质暴露率（DER）选择样本，其磨损阶段从未磨损到严重磨损。从高分辨率CT扫描获得的三维表面重建（PLY文件）中测量DNE、RFI和OPCR。通过回归分析测试变量之间的关系。
上臼齿有更多的切割边缘，表现出显著更高的DNE，但RFI值显著更低。然而，两组臼齿的测量指标之间的关系是一致的。DER和EDJL呈曲线相关。DER与DNE呈正相关，与RFI呈负相关，与OPCR不相关。EDJL与DNE或RFI不相关，但仅在下臼齿中与OPCR呈正相关。
这些指标之间的关系表明，嚎叫猴的牙齿能适应性地应对宏观磨损。在这个样本中，DNE随着磨损增加，可能有助于改善食物分解。RFI最初较高，但随着磨损而下降，表明最初较高的RFI可防止牙齿衰老。嚎叫猴牙齿的OPCR值与磨损变化没有明显关系。
