ABSTRACT Dental homologies and evolutionary transformations within caviomorph rodents have long been disputed. Here, we participate in these debates in providing new insights from the dental morphology of Paleogene caviomorphs from Peruvian Amazonia (Contamana and Shapaja). Their analyses and comparisons with many hystricognaths allow (1) to generalize some hypotheses previously proposed about occlusal morphology of caviomorph cheek teeth, and (2) to propose new ones. In caviomorphs, the third crest of upper teeth would correspond either to a mesoloph or to a mesolophule or to a combination of both. The transformation from a pentalophodont pattern to a tetralophodont pattern would be explained by the disappearance of the metaloph. Likewise, the transformation from a tetralophodont pattern to a trilophodont pattern is observed by the loss of the third crest. A direct transformation from a pentalophodont pattern to a trilophodont pattern is also observed. Concerning lower teeth, discrepancies of homologies are centered on the mesial cristids, which can be notably distinguished depending on their compositions and connections with other structures. The ancestral patterns of caviomorph lower molars and dp4s were likely tetralophodont and pentalophodont, respectively. However, schemes with five and four (even three) transverse cristids cannot be ruled out for the two loci, respectively.

中文翻译：

---

Caviomorpha（Hystricognathi，Rodentia）的牙齿同源性和进化转化：来自秘鲁亚马逊河古近纪的新数据

摘要 腔形啮齿动物的牙齿同源性和进化转变长期以来一直存在争议。在这里，我们参与了这些辩论，从秘鲁亚马逊河（Contamana 和 Shapaja）的古近纪 caviomorphs 的牙齿形态中提供新的见解。他们与许多 hystricognaths 的分析和比较允许 (1) 概括以前提出的一些关于 caviomorph 颊齿咬合形态的假设，以及 (2) 提出新的假设。在 caviomorphs 中，上牙的第三个牙冠将对应于 mesoloph 或 mesolophule 或两者的组合。从五齿兽图案到四齿兽图案的转变可以用金齿兽的消失来解释。同样地，通过第三冠的消失可以观察到从四齿兽模式到三齿兽模式的转变。还观察到从五齿兽图案到三齿兽图案的直接转变。关于下牙，同源性的差异集中在近中嵴上，这可以根据它们的组成和与其他结构的连接进行显着区分。caviomorph 下臼齿和 dp4s 的祖先模式可能分别是四齿兽和五齿兽。然而，对于这两个位点，不能分别排除具有五个和四个（甚至三个）横向嵴的方案。可以根据它们的组成和与其他结构的连接进行明显区分。caviomorph 下臼齿和 dp4s 的祖先模式可能分别是四齿兽和五齿兽。然而，对于这两个位点，不能分别排除具有五个和四个（甚至三个）横向嵴的方案。可以根据它们的组成和与其他结构的连接进行显着区分。caviomorph 下臼齿和 dp4s 的祖先模式可能分别是四齿兽和五齿兽。然而，对于这两个位点，不能分别排除具有五个和四个（甚至三个）横向嵴的方案。