Bony labyrinth morphology varies across marine mammals and contains key information regarding hearing sensitivity and ecology. The hearing ranges of globicephaline (Delphinidae: Globicephalinae) or melon-headed dolphins, known as “Blackfish,” have been extensively studied using acoustic technologies, but clade-wide morphological analysis of the bony labyrinth is lacking. In this study, we investigate the variation in hearing-relevant bony labyrinth morphology within globicephalines using μCT scans of isolated petrosals and digitally isolating the bony labyrinth of all species. Principal components analysis (PCA) of nine hearing-relevant measurements of the cochlea alongside a broader sampling of terrestrial and aquatic artiodactyls shows Orcaella brevirostris and other globicephalines with higher levels of facial asymmetry and potentially more specialized echolocation abilities plotting near Monodon monoceros, Delphinapterus leucas, and Orcinus orca. The remaining globicephalines, which have more symmetrical skulls and other unique and acoustically relevant attributes, plotted towards the middle of the echolocating odontocete portion of the PCA. Our analysis thus reveals that inner ear morphology may correlate with both facial skull morphology and echolocation specializations, as these are intertwined. Furthermore, this study illustrates how morphological analyses, especially those centered on hearing, may provide critical conservation-relevant information as direct access to audiograms becomes less tenable.

中文翻译：

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黑鱼的骨迷宫（海豚科：Globicephalinae）

海洋哺乳动物的骨迷宫形态各不相同，并包含有关听力敏感性和生态学的关键信息。已使用声学技术广泛研究了球头海豚（海豚科：球头海豚）或瓜头海豚（称为“黑鱼”）的听力范围，但缺乏对骨迷路的进化枝范围的形态分析。在这项研究中，我们使用孤立岩骨的 μCT 扫描和数字隔离所有物种的骨迷路来研究球脑内与听力相关的骨迷路形态的变化。对耳蜗的九种听力相关测量值的主成分分析 (PCA) 以及更广泛的陆地和水生偶蹄动物采样显示了短尾虎鲸和 其他 具有 更高 水平 的 面部 不对称 和 可能 更 专门 的 回声 定位 能力 的 球脑 素 , 在Monodon monoceros、Delphinapterus leucas和Orcinus orca附近绘图。其余的球头颅素，具有更对称的头骨和其他独特的和声学相关的属性，绘制在 PCA 回声定位齿状部分的中间。因此，我们的分析表明，内耳形态可能与面部颅骨形态和回声定位专业相关，因为它们是相互交织的。此外，这项研究说明了形态分析，特别是那些以听力为中心的分析，如何提供关键的保护相关信息，因为直接访问听力图变得不那么站得住脚了。