Understanding feeding ecology of extinct kangaroos is fundamental to understanding the evolution of kangaroos and the Australia paleoenvironment during the Oligo-Miocene. Comparisons with extant species have suggested that the macropodiforms of the Oligo/Miocene (kangaroos and allies) from the Riversleigh World Heritage Area, northern Australia, were predominantly folivorous browsers or fungivores, unlike the majority of extant species. To further test this hypothesis, we investigate the relationship between variation in cranial and mandibular shape of extant and extinct macropodiforms and ecological factors such as diet, locomotion, and body mass using 3D geometric morphometric analysis of 42 living species and eight extinct species from two radiations (the extinct clade of Balbaridae and some early representatives of the extant Macropodidae. Dietary class (fungivore, browser, grazer, and mixed feeder) correlated strongly with variation in cranial shape (20–25% of variance explained). There was also significant association between cranial shape, and both locomotor mode and body mass. In a principal component analysis of shape variation for crania (including the shape of the molar row), Riversleigh macropodiforms cluster with extant folivorous browsers on principal components (PC) 1 and 3, providing support for previous interpretations of these species as browsing kangaroos. However, as a group and regardless of phylogenetic association, the shape centroid of extinct species differs significantly from that of extant species. Riversleigh macropodiforms cluster with regular hoppers or arboreal tree kangaroos, but this may be a result of the correlation between diet and locomotor mode in kangaroos. Their similarity to extant browsers supports previous interpretations of rainforest and woodland environments at Riversleigh during the early and middle Miocene, respectively. Procrustes ANOVA Analysis of the full shape dataset and diet also shows that diet accounts for a significant portion of variation; however, when phylogeny is taken into account these results become nonsignificant. In analyses of dentary shape, some balbarid species cluster with extant mixed feeders, although this may reflect phylogenetic differences rather than ecological signal.

中文翻译：

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3D 形态测量分析揭示了来自澳大利亚 Riversleigh 世界遗产区的早期袋鼠（巨足科）和长牙袋鼠（巴尔巴里达科）的相似生态形态

了解已灭绝袋鼠的摄食生态是了解袋鼠进化和澳大利亚古环境在渐新世期间的基础。与现存物种的比较表明，与大多数现存物种不同，来自澳大利亚北部里弗斯利世界遗产区的寡头/中新世巨足类动物（袋鼠和盟友）主要是食叶食草动物或食真菌动物。为了进一步验证这一假设，我们使用来自两种辐射的 42 种现存物种和 8 种已灭绝物种的 3D 几何形态计量分析，研究了现存和已灭绝巨足类动物的颅骨和下颌骨形状的变化与生态因素（如饮食、运动和体重）之间的关系（巴尔巴科的灭绝分支和现存巨猿科的一些早期代表。饮食类别（食真菌动物、食肉动物、食草动物和混合饲养者）与颅骨形状的变化密切相关（解释了 20-25% 的变化）。颅骨形状与运动模式和体重之间也存在显着关联。在颅骨形状变化的主成分分析（包括臼齿行的形状）中，Riversleigh 巨脚类在主成分 (PC) 1 和 3 上与现存的食叶浏览器聚集在一起，为以前将这些物种解释为浏览袋鼠提供了支持。然而，作为一个群体，无论系统发育关联如何，已灭绝物种的形状质心与现存物种的形状质心显着不同。Riversleigh macropodiforms 与规则的漏斗或树栖树袋鼠成群结队，但这可能是袋鼠的饮食和运动模式之间存在相关性的结果。它们与现存浏览器的相似性支持先前对 Riversleigh 雨林和林地环境分别在早中新世和中新世的解释。Procrustes ANOVA 对完整形状数据集和饮食的分析也表明，饮食占变异的很大一部分；然而，当考虑到系统发育时，这些结果就变得不重要了。在牙齿形状的分析中，一些 balbarid 物种与现存的混合饲养者聚集在一起，尽管这可能反映了系统发育差异而不是生态信号。Procrustes ANOVA 对完整形状数据集和饮食的分析也表明，饮食占变异的很大一部分；然而，当考虑到系统发育时，这些结果就变得不重要了。在牙齿形状的分析中，一些 balbarid 物种与现存的混合饲养者聚集在一起，尽管这可能反映了系统发育差异而不是生态信号。Procrustes ANOVA 对完整形状数据集和饮食的分析也表明，饮食占变异的很大一部分；然而，当考虑到系统发育时，这些结果就变得不重要了。在牙齿形状的分析中，一些 balbarid 物种与现存的混合饲养者聚集在一起，尽管这可能反映了系统发育差异而不是生态信号。