Department of Anatomy, Midwestern University, Arizona 85308, USA.
Anat Rec (Hoboken). 2010 Oct;293(10):1711-21. doi: 10.1002/ar.21199. Epub 2010 Aug 20.
In recent years it has become possible to investigate the hearing capabilities in fossils by analogy with studies in living taxa that correlate the bony morphology of the auditory system with hearing sensitivity. In this analysis, we used a jack-knife procedure to test the accuracy of one such study that examined the functional morphology of the primate auditory system and we found that low-frequency hearing (sound pressure level at 250 Hz) can be predicted with relatively high confidence (±3-8 dB depending on the structure). Based on these functional relationships, we then used high-resolution computed tomography to examine the auditory region of three fossil New World monkeys (Homunculus, Dolicocebus, and Tremacebus) and compared their morphology and predicted low-frequency sensitivity with a phylogenetically diverse sample of extant primates. These comparisons reveal that these extinct taxa shared many auditory characteristics with living platyrrhines. However, the fossil with the best preserved auditory region (Homunculus) also displayed a few unique features such as the relative size of the tympanic membrane and stapedial footplate and the degree of trabeculation of the anterior accessory cavity. Still, the majority of evidence suggests that these fossil species likely had similar low-frequency sensitivity to extant South American monkeys. This research adds to the small but growing body of evidence on the evolution of hearing abilities in extinct taxa and lays the groundwork for predicting hearing sensitivity in additional fossil primate specimens.
近年来，通过与研究活体分类群的类比，人们已经可以研究化石的听力能力，这些分类群将听觉系统的骨骼形态与听力敏感度相关联。在这项分析中，我们使用了一种折刀程序来测试一项此类研究的准确性，该研究检查了灵长类动物听觉系统的功能形态，我们发现低频听力（250Hz 时的声压级）可以相对有信心地预测（取决于结构，准确度在±3-8dB 之间）。基于这些功能关系，我们然后使用高分辨率计算机断层扫描检查了三个新世界猴化石（Homunculus、Dolicocebus 和 Tremacebus）的听觉区域，并将它们的形态和预测的低频敏感度与现生灵长类动物的多样化样本进行了比较。这些比较表明，这些已灭绝的类群与现存的阔鼻猴具有许多听觉特征。然而，听觉区域保存最好的化石（Homunculus）也显示出一些独特的特征，例如鼓膜和镫骨足板的相对大小以及前辅助腔的小梁化程度。尽管如此，大多数证据表明，这些化石物种可能与现生的南美猴具有相似的低频敏感度。这项研究增加了关于已灭绝类群听力能力进化的少量但不断增长的证据，并为预测其他化石灵长类标本的听力敏感度奠定了基础。
