Institut Català de Paleontologia, Universitat Autònoma de Barcelona, Edifici ICP, Campus de la UAB s/n, E-08193 Cerdanyola del Vallès, Barcelona, Spain.
J Hum Evol. 2011 Jul;61(1):42-9. doi: 10.1016/j.jhevol.2011.01.003. Epub 2011 Mar 2.
Oreopithecus bambolii is one of the few hominoids that evolved under insular conditions, resulting in the development of unique adaptations that have fueled an intensive debate. The palaeoenvironment associated with this great ape has been the subject of great controversy as well. On the one hand, palaeobotanical data indicate that Oreopithecus likely inhabited mixed mesophytic forests interrupted by swamps; on the other hand, an abundance of hypsodont bovids points towards the existence of dry and open environments. Here, we provide a new approach based on the ecomorphology of the extinct endemic Muridae (rats and mice) of the so-called Oreopithecus faunas. Our results show that the successive species of endemic insular murids (Huerzelerimys and Anthracomys) evolved a number of adaptations observed only in extant family members that include significant proportions of grass in their diet. While this fits the pattern exhibited by large mammals, it contrasts with the available palaeobotanical information, which indicates that grasses were minor components of the vegetation. This contradiction may be explained because these endemic murids may have been adapted to the consumption of particular food items such as hard parts of aquatic plants (as shown by some extant murid species). However, because it is unlikely that the remaining herbivore mammals were adapted to this diet as well, we favour an alternative hypothesis that takes into account the peculiar ecological conditions of insular ecosystems leading to a density-dependent selective regime with strong competition. Such a regime would promote the selection of dental adaptations to increase feeding efficiency and durability of the dentition (such as hypsodonty) as seen in some fossil insular ruminants. This hypothesis requires further testing, but may partly account for parallel evolution of dental traits in phylogenetically unrelated insular mammals.
奥里诺科猴是少数在岛屿环境中进化的人科动物之一，这导致了独特适应性的发展，引发了激烈的争论。与这种大型猿类相关的古环境也一直存在很大争议。一方面，古植物学数据表明，奥里诺科猴可能生活在混合常绿森林中，森林中穿插着沼泽；另一方面，大量高齿牛科动物的存在表明存在干燥和开阔的环境。在这里，我们提供了一种基于所谓的奥里诺科猴动物群中已灭绝的特有鼠科（老鼠）的生态形态学的新方法。我们的结果表明，连续的特有岛屿鼠种（Huerzelerimys 和 Anthracomys）进化出了一些仅在现存的科成员中观察到的适应性，包括在其饮食中占很大比例的草。虽然这与大型哺乳动物的模式相符，但与现有的古植物学信息相矛盾，后者表明草是植被的次要组成部分。这种矛盾可能是因为这些特有鼠类可能已经适应了某些特定食物的消耗，例如水生植物的硬部分（一些现存的鼠类物种就是如此）。然而，由于不太可能其余的食草哺乳动物也适应这种饮食，我们倾向于另一种假设，该假设考虑到岛屿生态系统的特殊生态条件，导致具有强烈竞争的密度依赖选择性机制。这种机制将促进牙齿适应性的选择，以提高进食效率和牙齿的耐用性（如高齿性），就像一些化石岛屿反刍动物一样。这个假设需要进一步的测试，但可能部分解释了在系统发育上无关的岛屿哺乳动物中牙齿特征的平行进化。
