Groves Sabrina L, Peredo Carlos Mauricio, Pyenson Nicholas D
Department of Paleobiology, National Museum of Natural History, Washington, DC, USA.
Department of Biological Sciences, Mount Holyoke College, South Hadley, MA, USA.
PeerJ. 2021 Feb 5;9:e10882. doi: 10.7717/peerj.10882. eCollection 2021.
The history of cetaceans demonstrates dramatic macroevolutionary changes that have aided their transformation from terrestrial to obligate aquatic mammals. Their fossil record shows extensive anatomical modifications that facilitate life in a marine environment. To better understand the constraints on this transition, we examined the physical dimensions of the bony auditory complex, in relation to body size, for both living and extinct cetaceans. We compared the dimensions of the tympanic bulla, a conch-shaped ear bone unique to cetaceans, with bizygomatic width-a proxy for cetacean body size. Our results demonstrate that cetacean ears scale non-isometrically with body size, with about 70% of variation explained by increases in bizygomatic width. Our results, which encompass the breadth of the whale fossil record, size diversity, and taxonomic distribution, suggest that functional auditory capacity is constrained by congruent factors related to cranial morphology, as opposed to allometrically scaling with body size.
鲸类动物的进化史展现出了巨大的宏观进化变化，这些变化助力它们从陆生哺乳动物转变为完全水生的哺乳动物。它们的化石记录显示出广泛的解剖结构改变，这些改变有助于它们在海洋环境中生存。为了更好地理解这种转变所面临的限制因素，我们研究了现存和已灭绝鲸类动物的骨质听觉复合体的物理尺寸与体型之间的关系。我们将鼓泡（一种鲸类动物特有的海螺状耳骨）的尺寸与颧宽（一种代表鲸类动物体型的指标）进行了比较。我们的研究结果表明，鲸类动物的耳朵与体型并非等比例缩放，约70%的变异可由颧宽的增加来解释。我们的研究结果涵盖了鲸类化石记录的广度、体型多样性和分类分布，这表明功能性听觉能力受到与颅骨形态相关的一致因素的限制，而不是与体型呈异速生长缩放关系。
