Boyer Doug M, Toussaint Séverine, Godinot Marc
Duke University, Department of Evolutionary Anthropology, Durham, NC 27708, USA.
UFR Sciences Du Vivant, Université Paris Diderot-Paris 7, Sorbonne Universités, Centre de Recherche sur La Paléobiodiversité et Les Paléoenvironnements (CR2P, UMR 7207), CNRS/MNHN/UPMC, Paris, France.
J Hum Evol. 2017 Oct;111:202-215. doi: 10.1016/j.jhevol.2017.07.005. Epub 2017 Aug 29.
The fossil record of early primates is largely comprised of dentitions. While teeth can indicate phylogenetic relationships and dietary preferences, they say little about hypotheses pertaining to the positional behavior or substrate preference of the ancestral crown primate. Here we report the discovery of a talus bone of the dentally primitive fossil euprimate Donrussellia provincialis. Our comparisons and analyses indicate that this talus is more primitive than that of other euprimates. It lacks features exclusive to strepsirrhines, like a large medial tibial facet and a sloping fibular facet. It also lacks the medially positioned flexor-fibularis groove of extant haplorhines. In these respects, the talus of D. provincialis comes surprisingly close to that of the pen-tailed treeshrew, Ptilocercus lowii, and extinct plesiadapiforms for which tali are known. However, it differs from P. lowii and is more like other early euprimates in exhibiting an expanded posterior trochlear shelf and deep talar body. In overall form, the bone approximates more leaping reliant euprimates. The phylogenetically basal signal from the new fossil is confirmed with cladistic analyses of two different character matrices, which place D. provincialis as the most basal strepsirrhine when the new tarsal data are included. Interpreting our results in the context of other recent discoveries, we conclude that the lineage leading to the ancestral euprimate had already become somewhat leaping specialized, while certain specializations for the small branch niche came after crown primates began to radiate.
早期灵长类动物的化石记录主要由牙齿构成。虽然牙齿可以表明系统发育关系和饮食偏好，但对于与原始冠层灵长类动物的位置行为或底物偏好相关的假说却几乎没有说明。在此，我们报告了一种牙齿原始的化石真灵长类动物——省级东鲁西猴（Donrussellia provincialis）距骨的发现。我们的比较和分析表明，这块距骨比其他真灵长类动物的距骨更为原始。它缺乏狐猴型灵长类动物特有的特征，比如大的内侧胫骨关节面和倾斜的腓骨关节面。它也没有现存类人猿型灵长类动物位于内侧的屈肌 - 腓骨肌沟。在这些方面，省级东鲁西猴的距骨惊人地接近笔尾树鼩（Ptilocercus lowii）以及已知距骨的已灭绝的近猴类动物的距骨。然而，它与笔尾树鼩不同，在表现出扩大的后滑车嵴和深的距骨体方面更像其他早期真灵长类动物。从整体形态来看，这块骨头更接近更依赖跳跃的真灵长类动物。通过对两个不同特征矩阵的分支系统分析，证实了来自新化石的系统发育基部信号，当纳入新的跗骨数据时，该分析将省级东鲁西猴置于最基部的狐猴型灵长类动物位置。结合其他近期发现来解读我们的结果，我们得出结论，导致原始真灵长类动物的谱系已经在某种程度上变得专门适应跳跃，而针对小分支生态位的某些特化是在冠层灵长类动物开始辐射之后出现的。
