Many living primates that feed on hard food have been observed to have thick-enameled molars. Among platyrrhine primates, members of the tribe Pitheciini (Cacajao, Chiropotes, and Pithecia) are the most specialized seed and nut predators, and Cebus apella also includes exceptionally hard foods in its diet. To examine the hypothesized relationship between thick enamel and hard-object feeding, we sectioned small samples of molars from the platyrrhine primates Aotus trivergatus, Ateles paniscus, Callicebus moloch, Cebus apella, Cacajao calvus, Chiropotes satanas, Pithecia monachus, and Pithecia pithecia. We measured relative enamel thickness and examined enamel microstructure, paying special attention to the development of prism decussation and its optical manifestation, Hunter-Schreger Bands (HSB). Cebus apella has thick enamel with well-defined but sinuous HSB overlain by a substantial layer of radial prisms. Aotus and Callicebus have thin enamel consisting primarily of radial enamel with no HSB, Ateles has thin enamel with moderately developed HSB and an outer layer of radial prisms, and the thin enamel of the pitheciins (Cacajao, Chiropotes, and Pithecia) has extremely well-defined HSB. Among platyrrhines, two groups that feed on hard objects process these hard foods in different ways. Cebus apella masticates hard and brittle seeds with its thick-enameled cheek teeth. Pitheciin sclerocarpic foragers open hard husks with their canines but chew relatively soft and pliable seeds with their molars. These results reveal that thick enamel per se is not a prerequisite for hard object feeding. The Miocene hominoid Kenyapithecus may have included hard objects in its diet, but its thick-enameled molars indicate that its feeding adaptations differed from those of the pitheciins. The morphology of both the anterior and posterior dentition, including enamel thickness and microstructure, should be taken into consideration when inferring the dietary regime of fossil species.

中文翻译：

---

pitheciin灵长类动物的牙釉质厚度和微观结构，并评论中新世中型类人猿肯尼亚pithecus的饮食适应性。

据观察，以硬食为食的许多活灵长类动物的臼齿较厚。在普拉提灵长类动物中，Pitheciini部落（Cacajao，Chiropotes和Pithecia）的成员是最专业的种子和坚果食肉动物，Cebus apella的饮食中还含有特别坚硬的食物。为了检查假设的珐琅质与坚硬物体进食之间的关系，我们从香茅灵长类动物Aotus trivergatus，Ateles paniscus，Callicebus moloch，Cebus apella，Cacajao calvus，Chiropotes satanas，Pithecia monachus和Pithecia pithecia的小臼齿样本中进行了切片。我们测量了相对的牙釉质厚度并检查了牙釉质的微观结构，并特别注意了棱镜微影的发展及其光学表现，亨特·施格格带（HSB）。Cebus apella的牙釉质厚，轮廓分明但蜿蜒的HSB被大量的径向棱柱覆盖。Aotus和Callicebus的搪瓷薄，主要由放射状搪瓷组成，不含HSB； Ateles的搪瓷薄，具有适度发育的HSB和放射状棱柱的外层；而pitheciins的稀薄搪瓷（Cacajao，Chiropotes和Pithecia）具有极佳的釉质-定义的HSB。在桔梗中，以硬物为食的两组食物以不同的方式处理这些硬食物。Cebus apella的釉质浓密的颊齿可咀嚼硬而脆的种子。Pitheciin硬皮果食者用犬齿打开坚硬的果壳，但用其臼齿咀嚼相对较软且柔韧的种子。这些结果表明，厚搪瓷本身并不是硬物体进给的先决条件。中新世的类人猿肯尼亚皮猴在其饮食中可能含有坚硬的物体，但其浓密的珐琅臼齿表明其饲喂适应性不同于披皮霉素。推断化石物种的饮食方式时，应考虑前牙列和后牙列的形态，包括牙釉质的厚度和微观结构。