The Heteromyidae (pocket mice and kangaroo rats) are a group of extant small rodents abundant in western North America, as well as in fossil assemblages over the last 20 million years. Two genera of heteromyids, Chaetodipus and Perognathus, share similar tooth morphology and teeth are the primary fossil remains. Previous genetic studies show these extant sister genera likely diverged in the middle Miocene (~16 million years ago); however, the Chaetodipus fossil record starts in the Pleistocene (~2 million years ago). In this study, we asked whether two-dimensional geometric morphometrics on complete dentition and isolated premolars can accurately identify Chaetodipus and Perognathus specimens at the genus and species level. We landmarked the occlusal surface of the upper and lower tooth rows of modern Chaetodipus (n = 83) and Perognathus specimens (n = 80), including 12 of the 26 extant species across the two genera. We ran a canonical variates analysis to investigate whether principal component variation could predict known taxonomic identifications. The morphospace using complete dentition can identify specimens to genus with 90 – 92% accuracy and to species with more variable accuracy. We found an isolated premolar provides sufficient information for genus-level identification (69 – 84% accuracy), but not for species-level identification (26 – 56% accuracy). This morphospace of modern specimens can be used to identify the skeletal remains of Chaetodipus and Perognathus in museum collections, raptor pellets, or middens, to refine our existing knowledge of heteromyid evolutionary history.

中文翻译：

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使用 2D 牙科几何形态学来识别现代 Perognathus 和 Chaetodipus 标本（啮齿目，Heteromyidae）

Heteromyidae（袋鼠和袋鼠）是一组现存的小型啮齿动物，在北美西部以及过去 2000 万年的化石组合中很丰富。异足类的两个属，Chaetodipus 和 Perognathus，具有相似的牙齿形态，牙齿是主要的化石遗迹。先前的遗传研究表明，这些现存的姐妹属可能在中新世中期（约 1600 万年前）分化。然而，Chaetodipus 化石记录始于更新世（约 200 万年前）。在这项研究中，我们询问完整牙列和孤立前磨牙的二维几何形态计量学是否可以在属和种水平上准确识别 Chaetodipus 和 Perognathus 标本。我们标记了现代 Chaetodipus (n = 83) 和 Perognathus 标本 (n = 80) 的上下牙排的咬合面，包括两个属的 26 个现存物种中的 12 个。我们进行了典型变量分析，以研究主成分变化是否可以预测已知的分类学识别。使用完整牙列的形态空间可以以 90 – 92% 的准确度将标本识别为属，并以更可变的准确度识别物种。我们发现分离的前磨牙为属级鉴定提供了足够的信息（准确率为 69 – 84%），但不能为物种水平的鉴定提供足够的信息（准确率为 26 – 56%）。这种现代标本的形态空间可用于识别博物馆藏品、猛禽弹丸或蛞蝓中的 Chaetodipus 和 Perognathus 的骨骼遗骸，