Mesotheriidae were small to medium‐sized native South American ungulates. Mesotheriids radiated from the early Oligocene epoch to the early–middle Pleistocene, in two subfamilies: Trachytheriinae and Mesotheriinae. Beyond the conspicuous fossil record, little is known about mesotheriid palaeobiology, and particularly, the dietary habits. To date, different studies suggest grazing habits, similar to some extant ungulates, but recent contributions are challenging this vision. Here, we explore dietary preferences in mesotheriids, focusing on food intake and oral processing strategies. We performed a shape analysis of the snout and reconstructed ancestral shapes to assess evolutionary trends within the clade. Also, we considered other morphological variables of the masticatory apparatus to perform a functional characterization. We recognized three snout configurations: Trachytherus, ‘Intermediate’ and Mesotherium morphotypes that can be associated with different food intake capabilities and, considering other morphological proxies, with the consumption of different food items. Taking into account palaeoenvironmental conditions, the evolution of the masticatory apparatus is interpreted in the context of a consumption gradient from coarse and tough foods (roots, tubers, tough leaves) to grasses. We propose that during the ecomorphological evolution of mesotheriids, an initial phase took place during the late Oligocene and Miocene, consisting of diversification and specialization for consumption of hard‐to‐break food items. A second phase began incipiently during the late Miocene, and became well‐defined during the Pliocene and Pleistocene, characterized by an ecomorphological displacement towards grazing habits. Inferred dietary habits in Mesotheriidae could provide light on palaeoecological evolution and niche partitioning within South American herbivorous mammalian communities.

中文翻译：

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啮齿动物状等温线有蹄类动物的鼻息状和咀嚼器（Notoungulata，Typotheria）：通过祖先重建探索饮食策略的演变趋势

Mesotheriidae是南美洲有蹄类动物的中小型。Mesotheriids从渐新世早期辐射到中更新世早期，有两个亚科：Trachytheriinae和Mesotheriinae。除了显着的化石记录外，关于中温体古生物学尤其是饮食习惯还知之甚少。迄今为止，不同的研究提出了放牧习惯，类似于一些现存的有蹄类动物，但是最近的研究对这一观点提出了挑战。在这里，我们探讨中温疗法的饮食偏爱，重点是食物摄入和口腔加工策略。我们对口鼻部进行了形状分析，并重建了祖先形状，以评估进化枝内的进化趋势。此外，我们考虑了咀嚼器的其他形态变量来执行功能表征。Trachytherus，'intermediate'和Mesotherium可能与不同食物摄入能力相关的形态型，并考虑其他形态学指标，与不同食物的消费有关。考虑到古环境条件，咀嚼器的演变是根据从粗硬食物（块根，块茎，硬叶）到草的消费梯度来解释的。我们建议，在中温放线虫的生态形态演化过程中，始于渐新世和中新世晚期，包括多样化和专业化消费难碎食品的初始阶段。第二阶段始于中新世晚期，并在上新世和更新世期间定义明确，其特征是向放牧习惯的生态形态学位移。