Abstract Caviid rodents have peculiar craniomandibular specializations toward masticatory propalinal movements and grinding, in relation to a grass-rich diet. The aim of this study is to: (1) analyse the variation of cheek tooth shape in the Caviinae and, (2) quantify the covariation relations between caviine cheek teeth. For this purpose, we perform the first geometric morphometric analysis on cheek teeth of fossil and extant caviids, ancestral shape reconstructions and covariation analyses. Our results show that caviine dentition is strongly integrated with a higher covariation between teeth of the same row than between opposite teeth, differing from mammals with complex interlocking. Each series acts as a single functional unit integrated during grinding action obtained by mainly propalinal movements. However, p4 shows more plasticity, allowing its morphology to differentiate from the common pattern of molars. Morphologically homogeneous cheek tooth series are ancestral in crown caviids and highly marked in Cavia, while stronger morphological differences between tooth pieces are observed in Microcavia and Galea. These differences are probably driven by diet changes. The tendency towards alignment of main masticatory movements with the tooth row axes seems to be a key factor in understanding cheek tooth covariation patterns in this and other rodent clades.

中文翻译：

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磨食草食动物颊齿的整合模式和生态形态进化：以豚鼠啮齿动物为例（Caviomorpha：Caviidae）

摘要 Caviid 啮齿动物具有特殊的颅下颌骨特化，与富含草的饮食有关，咀嚼蜂巢运动和研磨。本研究的目的是：（1）分析颧骨牙齿形状的变化，（2）量化颧骨颧骨之间的协变关系。为此，我们首次对化石和现存豚鼠的颊齿进行几何形态测量分析、祖先形状重建和协变分析。我们的研究结果表明，与具有复杂互锁的哺乳动物不同，同排牙齿之间的协变比相对牙齿之间的协变更高。每个系列都作为一个单一的功能单元，在主要通过蜂胶运动获得的研磨作用期间集成。然而，p4 显示出更多的可塑性，使其形态与常见的臼齿模式区分开来。形态上均质的颊齿系列在冠腔中是祖先的，在腔中高度显着，而在 Microcavia 和 Galea 中观察到牙片之间的形态差异更强。这些差异可能是由饮食变化驱动的。主要咀嚼运动与牙排轴对齐的趋势似乎是理解该和其他啮齿动物进化枝中颊齿协变模式的关键因素。这些差异可能是由饮食变化驱动的。主要咀嚼运动与牙排轴对齐的趋势似乎是理解该和其他啮齿动物进化枝中颊齿协变模式的关键因素。这些差异可能是由饮食变化驱动的。主要咀嚼运动与牙排轴对齐的趋势似乎是理解该和其他啮齿动物进化枝中颊齿协变模式的关键因素。