Abstract The late Permian dicynodont Endothiodon is characterized by its specialized feeding system, most notably manifested in its long rows of post-canine teeth and corresponding keratinous surfaces. This specialisation has fuelled discussion of not only the masticatory biomechanics in Endothiodon but also of its diet and ecology. To shed light on the latter two, we compared the oxygen (δ18Op) and carbon (δ13Cc) stable isotope compositions of Endothiodon tooth and bone apatite with those of the co-occurring dicynodont Tropidostoma, another late Permian dicynodont of similar size. Preliminary results indicate that Endothiodon had significantly lower ratios for stable isotopes of both oxygen and carbon. The δ18Op values from Endothiodon suggest that its lifestyle was more water-dependent (i.e. obligate drinker) than Tropidostoma, pointing to the possibility of a semi-aquatic ecology, whereas δ13Cc values suggest that Endothiodon had a diet primarily comprising riparian vegetation, with the possibility that juveniles consumed terrestrial insects. The data suggest a negligible role for roots, seeds, or algae in the diet of Endothiodon.

中文翻译：

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稳定同位素（δ18O 和 δ13C）为来自南非卡鲁盆地晚二叠世的 Endothiodon Bathystoma（Therapsida、Dicynodontia）的生态和饮食提供了新的视角

摘要 晚二叠世二齿兽类 Endothiodon 的特点是其特殊的摄食系统，最显着的是其长排的后犬齿和相应的角质表面。这种专业化不仅引发了对 Endothiodon 咀嚼生物力学的讨论，还引发了对其饮食和生态学的讨论。为了阐明后两者，我们比较了 Endothiodon 牙齿和骨磷灰石的氧 (δ18Op) 和碳 (δ13Cc) 稳定同位素组成与共同发生的二齿兽 Tropidostoma（另一种类似大小的晚二叠世二齿兽）的稳定同位素组成。初步结果表明，Endothiodon 的氧和碳稳定同位素比率明显较低。来自 Endothiodon 的 δ18Op 值表明它的生活方式比 Tropidostoma 更依赖水（即专性饮水），指出半水生生态的可能性，而 δ13Cc 值表明 Endothiodon 的饮食主要包括河岸植被，幼鱼可能食用陆生昆虫。数据表明根、种子或藻类在 Endothiodon 的饮食中的作用可以忽略不计。