Abstract: The diets and environments of fossil rhinocerotoids from the Linxia Basin, Gansu, China,ranging in age from 25 to 2.5 Ma, were reconstructed based on bulk and serial carbon (C) and oxygen (O) isotope analyses of tooth enamel. The results support many previous hypotheses inferred from dentition and cranial and limb morphology and offer new insight on the paleoecology of some genera. The isotopic results support the following previous hypotheses: the Late Oligocene rhinoParaceratherium inhabited a forested environment, and the coexisting rhino Allacerops lived in a relatively open habitat and had a less specialized diet; the Middle Miocene Hispanotherium grazed in open territory, whereas the contemporaneous Alicornops had a more generalized diet in a forested environment; and the Late Miocene rhino Parelasmotherium grazed in an open steppe habitat. The isotope data indicate that the rhinos Acerorhinus and Dicerorhinus inhabited open steppe environments, inconsistent with previous inferences that these two rhinos dwelled in forested environments. The isotopic results are not conclusive concerning the habitat of Iranotherium, but support previous hypotheses that this rhino was a specialized C3 grazer. The results also suggest thatChilotherium was a forest-dweller throughout much of the Late Miocene, but occupied a more open environment by the end of the Late Miocene. Additionally, the results are consistent with previous hypotheses that the Pliocene rhino Shansirhinus and the Pleistocene rhino Coelodonta were grazers in open habitats. Finally, the C isotope data support that all rhinos in this study were pure C3 feeders,confirming that C4 grasses were not an important component of the plant biomass in the Linxia Basin from 25 to 2.5 Ma. 

摘要： 根据牙齿釉质的全样和系列碳、氧同位素分析，重建了甘肃临夏盆地25~2.5Ma期间犀牛的食性和环境。其结果支持先前根据牙齿和头骨-肢骨形态做出的一些推断，并对部分属的古生态提出了新的看法。同位素结果支持如下的推断：晚渐新世的巨犀Paraceratherium生活于森林环境，而与其共生的异角犀Allacerops栖息地相对开阔，食性特化程度低；中中新世的西班牙犀Hispanotherium在开阔领地上取食草本植物，而同时代的奇角犀Alicornops在森林环境中具有更特化的食性；晚中新世的副板齿犀Parelasmotherium在开阔的稀树草原上取食草本植物。与先前认为无鼻角犀Acerorhinus和额鼻角犀Dicerorhinus生活于森林化环境的推断不同，数据指示这两种犀牛也生活于开阔的稀树草原环境。同位素结果未能得出伊朗犀Iranotherium的确切生活环境，但支持先前认为它特化为C3草本植物取食者的推断。研究结果也显示大唇犀Chilotherium在晚中新世的大多数时间内是森林生活者，但其在晚中新世末期占据了更开阔的环境。此外，分析结果与先前的推断一致，即上新世的山西犀Shansirhinus和更新世的披毛犀Coelodonta是开阔生活环境中的食草者。最后，碳同位素数据支持在此项研究中的所有犀牛都是纯C3取食者，确认C4植物不是临夏盆地从25Ma到2.5Ma期间植被的重要成分。