Homunculus patagonicus is a stem platyrrhine from the late Early Miocene, high-latitude Santa Cruz Formation, Argentina. Its distribution lies farther south than any extant platyrrhine species. Prior studies on the dietary specialization of Homunculus suggest either a mixed diet of fruit and leaves or a more predominantly fruit-eating diet. To gain further insight into the diet of Homunculus, we examined how the occlusal surfaces of the first and second lower molars of Homunculus change with wear by using three homology-free dental topographic measures: Dirichlet normal energy (DNE), orientation patch count rotated (OPCR), and relief index (RFI). We compared these data with wear series of three extant platyrrhine taxa: the folivorous Alouatta, and the frugivorous Ateles and Callicebus (titi monkeys now in the genus Plecturocebus). Previous studies found Alouatta and Ateles exhibit distinctive patterns of change in occlusal morphology with macrowear, possibly related to the more folivorous diet of the former. Based on previous suggestions that Homunculus was at least partially folivorous, we predicted that changes in dental topographic metrics with wear would follow a pattern more similar to that seen in Alouatta than in Ateles or Callicebus. However, wear-induced changes in Homunculus crown sharpness (DNE) and complexity (OPCR) are more similar to the pattern observed in the frugivorous Ateles and Callicebus. Based on similar wear modalities of the lower molars between Homunculus and Callicebus, we infer that Homunculus had a primarily frugivorous diet. Leaves may have provided an alternative dietary resource to accommodate fluctuation in seasonal fruiting abundance in the high-latitude extratropical environment of late Early Miocene Patagonia.

中文翻译：

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牙形长大变化和饮食推断的齿形变化。

Homunculus patagonicus是来自中新世早期，高纬度阿根廷圣克鲁斯组的茎桔梗。它的分布比任何现存的桔梗种类都更靠南。先前有关鼠尾草的饮食专长的研究表明，水果和树叶的混合饮食或以水果为主的饮食。为了进一步了解沙门氏菌的饮食，我们通过使用三种无同源性的牙齿地形学方法检查了沙门氏菌第一和第二下磨牙的咬合面如何随磨损而变化：狄利克雷正态能量（DNE），取向斑计数旋转（ OPCR）和救济指数（RFI）。我们将这些数据与三个现存的桔梗类群的磨损系列进行了比较：叶类Alouatta，以及食肉性Ateles和Callicebus（现在属于电单胞菌属的Titi猴子）。先前的研究发现，Alouatta和Ateles的咬合形态随宏观穿着表现出独特的变化模式，这可能与前者的较节食有关。根据以前的建议，即Homunculus至少部分是有叶的，我们预测随着磨损的牙齿地形学指标的变化将遵循与Alouatta（而不是Ateles或Callicebus）相似的模式。但是，磨损引起的Homunculus冠状锐度（DNE）和复杂性（OPCR）的变化与在节食的Ateles和Callicebus中观察到的模式更为相似。基于Homunculus和Callicebus之间的下磨牙的类似磨损方式，我们推断Homunculus的饮食主要是节食的。