Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine, Medical Sciences Building, One Hospital Drive DC055.07, Columbia, MO 65212, USA.
Am J Primatol. 2010 Feb;72(2):161-72. doi: 10.1002/ajp.20767.
Lemurs are notable for encompassing the range of body-size variation for all primates past and present-close to four orders of magnitude. Benefiting from the phylogenetic proximity of subfossil lemurs to smaller-bodied living forms, we employ allometric data from the skull to probe the ontogenetic bases of size differentiation and morphological diversity across these clades. Building upon prior pairwise comparisons between sister taxa, we performed the first clade-wide analyses of craniomandibular growth allometries in 359 specimens from 10 lemuroids and 176 specimens from 8 indrioids. Ontogenetic trajectories for extant forms were used as a criterion of subtraction to evaluate morphological variation, and putative adaptations among sister taxa. In other words, do species-level differences in skull form result from the differential extension of common patterns of relative growth?In lemuroids, a pervasive pattern of ontogenetic scaling is observed for facial dimensions in all genera, with three genera also sharing relative growth trajectories for jaw proportions (Lemur, Eulemur, Varecia). Differences in masticatory growth and form characterizing Hapalemur and fossil Pachylemur likely reflect dietary factors. Pervasive ontogenetic scaling characterizes the facial skull in extant Indri, Avahi, and Propithecus, as well as their larger, extinct sister taxa Mesopropithecus and Babakotia. Significant interspecific differences are observed in the allometry of indrioid masticatory proportions, with variation in the mechanical advantage of the jaw adductors and stress-resisting elements correlated with diet. As the growth series and adult data are largely coincidental in each clade, interspecific variation in facial form may result from selection for body-size differentiation among sister taxa. Those cases where trajectories are discordant identify potential dietary adaptations linked to variation in masticatory forces during chewing and biting. Although such dissociations highlight selection to uncouple shared ancestral growth patterns, they occur largely via transpositions and retention of primitive size-shape covariation patterns or relative growth coefficients.
狐猴的身体大小变化范围在所有过去和现在的灵长类动物中都很显著——接近四个数量级。由于亚化石狐猴与体型较小的现存形式在系统发育上非常接近，我们利用颅骨的比例数据来探究这些类群中体型分化和形态多样性的个体发生基础。在之前对姐妹分类群进行的两两比较的基础上，我们对 10 种狐猴和 176 种指猴的 359 个标本进行了首次全谱系颅颌生长比例的分析。现存形式的个体发生轨迹被用作减法的标准，以评估形态变异和姐妹分类群之间的假定适应。换句话说，颅骨形态的种间差异是否来自于相对生长的共同模式的差异扩展？在狐猴中，所有属的面部尺寸都表现出普遍的个体发生比例模式，其中三个属的下颌比例也具有相对生长轨迹（狐猴、环尾狐猴和环尾狐猴）。哈氏狐猴和化石巴氏狐猴咀嚼生长和形态的差异可能反映了饮食因素。现生的指猴、巨指猴和原猴，以及它们较大的已灭绝姐妹分类群中腭猴和巴巴库猴，其颅面骨骼都具有普遍的个体发生比例模式。在指猴类的咀嚼比例的比例中观察到显著的种间差异，下颌内收肌的机械优势和抗压元素的变异与饮食有关。由于每个类群的生长系列和成年数据在很大程度上是一致的，因此面部形态的种间差异可能是由于姐妹分类群之间的体型分化选择所致。在轨迹不一致的情况下，确定与咀嚼和咬合力变化相关的潜在饮食适应。虽然这种分离强调了选择以解耦共享的祖先生长模式，但它们主要通过转换和保留原始的大小形状协变模式或相对生长系数来发生。
