Marchi Damiano, Ruff Christopher B, Capobianco Alessio, Rafferty Katherine L, Habib Michael B, Patel Biren A
Department of Biology, University of Pisa, Pisa, 56126, Italy.
Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, WITS 2050, South Africa.
J Morphol. 2016 Sep;277(9):1199-218. doi: 10.1002/jmor.20569. Epub 2016 Jun 20.
Palaeopropithecids, or "sloth lemurs," are a diverse clade of large-bodied Malagasy subfossil primates characterized by their inferred suspensory positional behavior. The most recently discovered genus of the palaeopropithecids is Babakotia, and it has been described as more arboreal than Mesopropithecus, but less than Palaeopropithecus. In this article, the within-bone and between-bones articular and cross-sectional diaphyseal proportions of the humerus and femur of Babakotia were compared to extant lemurs, Mesopropithecus and Palaeopropithecus in order to further understand its arboreal adaptations. Additionally, a sample of apes and sloths (Choloepus and Bradypus) are included as functional outgroups composed of suspensory adapted primates and non-primates. Results show that Babakotia and Mesopropithecus both have high humeral/femoral shaft strength proportions, similar to extant great apes and sloths and indicative of forelimb suspensory behavior, with Babakotia more extreme in this regard. All three subfossil taxa have relatively large femoral heads, also associated with suspension in modern taxa. However, Babakotia and Mesopropithecus (but not Palaeopropithecus) have relatively small femoral head surface area to shaft strength proportions suggesting that hind-limb positioning in these taxa during climbing and other behaviors was different than in extant great apes, involving less mobility. Knee and humeral articular dimensions relative to shaft strengths are small in Babakotia and Mesopropithecus, similar to those found in modern sloths and divergent from those in extant great apes and lemurs, suggesting more sloth-like use of these joints during locomotion. Mesopropithecus and Babakotia are more similar to Choloepus in humerofemoral head and length proportions while Palaeopropithecus is more similar to Bradypus. These results provide further evidence of the suspensory adaptations of Babakotia and further highlight similarities to both extant suspensory primates and non-primate slow arboreal climbers and hangers. J. Morphol. 277:1199-1218, 2016. © 2016 Wiley Periodicals, Inc.
古原狐猴，即“懒狐猴”，是马达加斯加亚化石灵长类动物中的一个多样化分支，其特征是具有推测的悬吊姿势行为。古原狐猴中最近发现的属是巴氏古原狐猴，据描述它比中狐猴更适应树栖生活，但不如古原狐猴。在本文中，将巴氏古原狐猴的肱骨和股骨的骨内及骨间关节和骨干横截面比例与现存狐猴、中狐猴和古原狐猴进行了比较，以进一步了解其树栖适应性。此外，还纳入了一组猿类和树懒（二趾树懒属和三趾树懒属）作为功能外类群，它们由适应悬吊的灵长类动物和非灵长类动物组成。结果表明，巴氏古原狐猴和中狐猴的肱骨干/股骨干强度比例都很高，类似于现存的大型猿类和树懒，表明有前肢悬吊行为，在这方面巴氏古原狐猴更为极端。所有这三个亚化石类群的股骨头都相对较大，这也与现代类群中的悬吊行为有关。然而，巴氏古原狐猴和中狐猴（但不包括古原狐猴）的股骨头表面积与骨干强度比例相对较小，这表明这些类群在攀爬和其他行为过程中的后肢定位与现存大型猿类不同，活动能力较弱。巴氏古原狐猴和中狐猴的膝关节和肱骨关节尺寸相对于骨干强度较小，类似于现代树懒，与现存大型猿类和狐猴不同，这表明在运动过程中这些关节的使用方式更像树懒。中狐猴和巴氏古原狐猴在肱股头和长度比例上与二趾树懒更相似，而古原狐猴与三趾树懒更相似。这些结果为巴氏古原狐猴的悬吊适应性提供了进一步的证据，并进一步突出了它与现存悬吊灵长类动物以及非灵长类慢速树栖攀爬者和悬挂者的相似性。《形态学杂志》277:1199 - 1218，2016年。©2016威利期刊公司。
