Protypotherium (Mammalia, Notoungulata, lnteratheriinae) is a well-known and very diverse genus of extinct native ungulates of South America, widely distributed from southern to middle latitudes of Argentina, Chile, and Bolivia. This genus exhibits distinctive species throughout the Miocene to the beginning of the Pliocene that display an interesting size pattern. The large sample of specimens studied during several years of research allows us to analyze the shape and size of upper and lower molars for nine species of Protypotherium , in order to test the hypothesis of reduction of size ranges preserving a general tooth morphology as a response to climate deterioration, documented in South America by a marked reduction of temperature that occurred during Miocene times. Elliptic Fourier analyses were used to capture the shape of the occlusal morphology and the centroid size was also retained for subsequent analyses. Our results demonstrate that: 1) a similar morphological tooth pattern is observed among all species; 2) tooth shape variation is not associated with a change in size; and 3) there is a tendency to increase the size and decrease the number of species. This striking pattern could be correlated with a global trend to lower temperatures, which indicates a deterioration of paleoenvironmental conditions. A conservative tooth pattern, together with an increase of size and a reduction in number of species were the main evolutionary and ecological tendencies accounted in Protypotherium from the early to late Miocene-beginning of the Pliocene, which were accompanied by a latitudinal displacement from Patagonia to northern areas at the end of the Miocene.

中文翻译：

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整个南美洲中新世 Protypotherium (Interatheriidae, Notoungulata) 谱系的进化趋势

Protypotherium (Mammalia, Notoungulata, lnteratheriinae) 是南美洲已灭绝的本土有蹄类动物的一个众所周知且非常多样化的属，广泛分布于阿根廷、智利和玻利维亚的南纬至中纬。该属在整个中新世到上新世开始都表现出独特的物种，显示出有趣的大小模式。在数年的研究中研究的大量样本使我们能够分析九种 Protypotherium 的上下臼齿的形状和大小，以测试大小范围缩小的假设，保留一般牙齿形态作为对牙齿的反应。气候恶化，在南美洲记录在中新世时期发生的温度显着降低。椭圆傅里叶分析用于捕捉咬合形态的形状，质心尺寸也被保留用于后续分析。我们的结果表明：1）在所有物种中观察到相似的形态牙齿图案；2) 齿形变化与尺寸变化无关；3）有增加规模和减少物种数量的趋势。这种惊人的模式可能与全球气温降低趋势相关，这表明古环境条件正在恶化。保守的牙齿图案，连同大小的增加和物种数量的减少是 Protypotherium 从上新世早期到晚期中新世开始的主要进化和生态趋势，