Phalangeal curvature and positional behavior in extinct sloth lemurs (Primates, Palaeopropithecidae)
Phalangeal curvature and positional behavior in extinct sloth lemurs (Primates, Palaeopropithecidae)
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DOI：
10.1073/pnas.94.22.11998
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发表时间：
1997-10-28
影响因子：
11.1
通讯作者：
Chatrath, PS
中科院分区：
文献类型：
--
作者：
Jungers, WL;Godfrey, LR;Chatrath, PS
最近在马达加斯加的古生物学发现记录了一个不同的palaeopropithecids或“树懒狐猴”的分支的存在：Mesopropithecus（三个物种），Babakotia（一个物种），Palaeopropithecus（三个物种），和Escheoindris（一个物种），这种现已灭绝的小辐射（“亚化石”）狐猴与现存的indrids（Indri，Propithecus和Avahi）关系最密切。现存的大狐猴以其跳跃的杂技而闻名，而古狐猴科（也许除了鲜为人知的巨型大狐猴）表现出许多反前行或悬挂位置行为的骨骼设计特征（例如，高的膜间指数和移动的关节）。在这里，我们分析了手和脚的近端趾骨的弯曲，计算为夹角（θ），趾骨弯曲的发展是对机械使用的响应，并且已知在灵长类动物中与不同栖息地的手和脚功能相关;陆栖物种的趾骨比树栖物种的趾骨更直，高度悬空的物种如猩猩拥有最弯曲的趾骨，树懒狐猴作为一个群体的特点是非常弯曲的近端趾骨，超过蜘蛛猴和合趾猴，接近猩猩。印度狐猴的弯曲度大约是树懒狐猴的一半，而更陆生的亚化石古狐猴拥有所有印度狐猴中弯曲度最小的指骨。结合它们颅后解剖学的许多其他衍生方面，指骨弯曲表明树懒狐猴是哺乳动物进化史上最具悬浮性的分支之一。
Recent paleontological discoveries in Madagascar document the existence of a diverse clade of palaeopropithecids or ''sloth lemurs'': Mesopropithecus (three species), Babakotia (one species), Palaeopropithecus (three species), and Archaeoindris (one species), This mini-radiation of now extinct (''subfossil'') lemurs is most closely related to the living indrids (Indri, Propithecus, and Avahi). Whereas the extant indrids are known for their leaping acrobatics, the palaeopropithecids (except perhaps for the poorly known giant Archaeoindris) exhibit numerous skeletal design features for antipronograde or suspensory positional behaviors (e.g., high intermembral indices and mobile joints). Here we analyze the curvature of the proximal phalanges of the hands and feet, Computed as the included angle (theta), phalangeal curvature develops in response to mechanical use and is known to be correlated in primates with hand and foot function in different habitats; terrestrial species have straighter phalanges than their arboreal counterparts, and highly suspensory forms such as the orangutan possess the most curved phalanges, Sloth lemurs as a group are characterized by very curved proximal phalanges, exceeding those seen in spider monkeys and siamangs, and approaching: that of orangutans. Indrids have curvatures roughly half that of sloth lemurs, and the more terrestrial, subfossil Archaeolemur possesses the least curved phalanges of all the indroids. Taken together with many other derived aspects of their postcranial anatomy, phalangeal curvature indicates that the sloth lemurs are one of the most suspensory clades of mammals ever to evolve.