Deane Andrew S, Russo Gabrielle A, Muchlinski Magdalena N, Organ Jason M
Department of Anatomy and Neurobiology, University of Kentucky, College of Medicine, MN 224 UK Medical Center, Lexington, Kentucky, 40536.
J Morphol. 2014 Nov;275(11):1300-11. doi: 10.1002/jmor.20304. Epub 2014 Jun 11.
Prehensile tails, capable of suspending the entire body weight of an animal, have evolved in parallel in New World monkeys (Platyrrhini): once in the Atelinae (Alouatta, Ateles, Brachyteles, Lagothrix), and once in the Cebinae (Cebus, Sapajus). Structurally, the prehensile tails of atelines and cebines share morphological features that distinguish them from nonprehensile tails, including longer proximal tail regions, well-developed hemal processes, robust caudal vertebrae resistant to higher torsional and bending stresses, and caudal musculature capable of producing higher contractile forces. The functional significance of shape variation in the articular surfaces of caudal vertebral bodies, however, is relatively less well understood. Given that tail use differs considerably among prehensile and nonprehensile anthropoids, it is reasonable to predict that caudal vertebral body articular surface area and shape will respond to use-specific patterns of mechanical loading. We examine the potential for intervertebral articular surface contour curvature and relative surface area to discriminate between prehensile-tailed and nonprehensile-tailed platyrrhines and cercopithecoids. The proximal and distal intervertebral articular surfaces of the first (Ca1), transitional and longest caudal vertebrae were examined for individuals representing 10 anthropoid taxa with differential patterns of tail-use. Study results reveal significant morphological differences consistent with the functional demands of unique patterns of tail use for all vertebral elements sampled. Prehensile-tailed platyrrhines that more frequently use their tails in suspension (atelines) had significantly larger and more convex intervertebral articular surfaces than all nonprehensile-tailed anthropoids examined here, although the intervertebral articular surface contour curvatures of large, terrestrial cercopithecoids (i.e., Papio sp.) converge on the ateline condition. Prehensile-tailed platyrrhines that more often use their tails in tripodal bracing postures (cebines) are morphologically intermediate between atelines and nonprehensile tailed anthropoids.
能悬挂动物整个体重的抓握性尾巴在新大陆猴（阔鼻猴亚目）中平行进化：一次出现在蛛猴科（蛛猴属、绒毛蛛猴属、吼猴属、长毛吼猴属），另一次出现在卷尾猴科（卷尾猴属、松鼠猴属）。在结构上，蛛猴科和卷尾猴科的抓握性尾巴具有一些形态特征，这些特征将它们与非抓握性尾巴区分开来，包括近端尾巴区域更长、血窦突发育良好、尾椎强壮能承受更高的扭转和弯曲应力，以及能够产生更高收缩力的尾部肌肉组织。然而，尾椎椎体关节面形状变化的功能意义相对了解较少。鉴于抓握性和非抓握性类人猿使用尾巴的方式有很大差异，合理预测尾椎椎体关节面面积和形状会对特定使用模式下的机械负荷做出反应。我们研究了椎间关节面轮廓曲率和相对表面积区分有抓握性尾巴和无抓握性尾巴的阔鼻猴类和猕猴类的潜力。对代表10种类人猿分类群且尾巴使用模式不同的个体，检查了第一尾椎（Ca1）、过渡性和最长尾椎的近端和远端椎间关节面。研究结果显示，对于所有采样的椎骨元素，存在与独特尾巴使用模式的功能需求一致的显著形态差异。更频繁在悬挂中使用尾巴的有抓握性尾巴的阔鼻猴（蛛猴科），其椎间关节面明显更大且更凸，比这里检查的所有无抓握性尾巴的类人猿都大，不过大型陆生猕猴类（即狒狒属）的椎间关节面轮廓曲率接近蛛猴科的情况。更常以三脚架支撑姿势使用尾巴的有抓握性尾巴的阔鼻猴（卷尾猴科）在形态上介于蛛猴科和无抓握性尾巴的类人猿之间。
