Department of Anatomy and Neurobiology, Northeastern Ohio Universities College of Medicine, Rootstown, OH 44272, USA.
Am J Phys Anthropol. 2010 Aug;142(4):519-30. doi: 10.1002/ajpa.21251.
Jaw-joint height (JJH) above the occlusal plane is thought to be influenced by cranial base angle (CBA) and facial angulation during growth. To better understand how JJH relates to midline craniofacial form, we test the hypothesis that relative increases in JJH are correlated with increasing CBA flexion and facial kyphosis (i.e., ventral bending) across primates. We compared JJH above the occlusal plane to CBA and the angle of facial kyphosis (AFK) across adults from 82 species. JJH scales with positive allometry relative to a skull geometric mean in anthropoids and most likely strepsirrhines. Anthropoid regressions for JJH are elevated above strepsirrhines, whereas catarrhines exhibit a higher slope than platyrrhines. Semipartial correlations between relative JJH and both CBA and AFK show no association across a small strepsirrhine sample, limited associations among catarrhines and anthropoids, but strong correlations in platyrrhines. Contrary to our hypothesis, however, increases in relative JJH are correlated with relatively less flexed basicrania and more airorhynch faces (i.e., reduced ventral bending) in platyrrhines. The mosaic pattern of relationships involving JJH across primate clades points to multiple influences on JJH across primates. In clades showing little association with basicranial and facial angles, such as strepsirrhines, the potential morphological independence of JJH may facilitate a relative freedom for evolutionary changes related to masticatory function. Finally, failure to associate relative JJH and basicranial flexion in most clades suggests that the relatively taller JJH and more flexed basicrania of anthropoids compared to strepsirrhines may have evolved as an isolated event during the origin of anthropoids.
颌关节高度（JJH）高于咬合平面被认为受颅基底角度（CBA）和生长期间面部角度的影响。为了更好地理解 JJH 与中线颅面形态的关系，我们检验了这样一个假设，即在灵长类动物中，JJH 的相对增加与 CBA 弯曲度的增加以及面部后凸（即腹侧弯曲）的增加有关。我们比较了 82 个物种的成人中，咬合平面以上的 JJH 与 CBA 和面部后凸角（AFK）的关系。在类人猿和大多数可能的原始猴中，JJH 与头骨几何平均值呈正异速生长。类人猿的 JJH 回归曲线高于原始猴，而猫猴类的斜率高于阔鼻猴类。相对 JJH 与 CBA 和 AFK 之间的半偏相关在一个小的原始猴样本中没有关联，在猫猴类和类人猿中关联有限，但在阔鼻猴类中相关性很强。然而，与我们的假设相反，在阔鼻猴类中，相对 JJH 的增加与相对较不弯曲的颅基底和空气口鼻面（即减少腹侧弯曲）有关。涉及 JJH 的灵长类动物分支的镶嵌关系模式表明，JJH 在灵长类动物中受到多种因素的影响。在与颅基底和面部角度关联不大的分支中，如原始猴类，JJH 的潜在形态独立性可能为与咀嚼功能相关的进化变化提供相对自由。最后，在大多数分支中，相对 JJH 与颅基底弯曲度没有关联，这表明与原始猴类相比，类人猿的 JJH 相对较高，颅基底较弯曲，这可能是类人猿起源时的一个孤立事件。
