German R Z
Am J Phys Anthropol. 1982 Aug;58(4):453-9. doi: 10.1002/ajpa.1330580414.
New World monkeys vary considerably in the manner and degree to which they use their tails. There ought to arise a corresponding variation in the stresses on caudal vertebrae. Consequently, different behavior types will have contrasting caudal morphologies. This study investigates caudal morphology of several New World monkeys representing the large range of ability from totally nonprehensile tails to the dexterous fifth limb of spider monkeys. One large-bodied, nonprehensile-tailed Old World monkey is included to offset the correlation between size and degree of prehensility in New World monkeys. These monkeys vary both within and between species as to the number of caudal vertebrae and the length of individual vertebrae. Despite this variation, the length of caudal vertebrae within a given tail decreases at a constant rate across species. The width of the vertebrae at two points, midbone and the proximal end, separates the monkeys with prehensile tails from those with nonprehensile tails. The middle of the vertebrae is wider and more robust in prehensile-tailed forms. This is associated with stronger bones in tails subject to greater stress. THe proximal width of each bone is also greater in the prehensile-tailed monkeys. This measure reflects the lateral development of the proximal transverse process. This provides a larger lever arm for M. caudalis lateralis, implying greater rotational ability.
新大陆猴在使用尾巴的方式和程度上有很大差异。因此，尾椎骨所承受的压力应该会出现相应的变化。相应地，不同的行为类型会有截然不同的尾部形态。本研究调查了几种新大陆猴的尾部形态，这些猴子代表了从完全无抓握能力的尾巴到蜘蛛猴灵活的第五肢等广泛的能力范围。还纳入了一种体型较大、尾巴无抓握能力的旧大陆猴，以抵消新大陆猴体型与抓握能力程度之间的相关性。这些猴子在尾椎骨数量和单个椎骨长度方面，种内和种间都存在差异。尽管存在这种差异，但在给定的尾巴中，尾椎骨的长度在不同物种间以恒定速率递减。在两个点，即椎骨中部和近端，椎骨的宽度将有抓握能力尾巴的猴子与无抓握能力尾巴的猴子区分开来。有抓握能力尾巴的猴子，其椎骨中部更宽且更粗壮。这与承受更大压力的尾巴中更强壮的骨骼有关。有抓握能力尾巴的猴子每块骨头的近端宽度也更大。这一测量反映了近端横突的侧向发育。这为尾外侧肌提供了更大的杠杆臂，意味着更强的旋转能力。
