School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg, South Africa.
Department of Anatomy, University of Pretoria, Pretoria, South Africa.
Am J Phys Anthropol. 2019 Nov;170(3):439-446. doi: 10.1002/ajpa.23901. Epub 2019 Jul 10.
Morphological variation within the southern African hypodigm of Paranthropus has been the focus of major interest since the earliest discoveries in the "Cradle of Humankind." Given the relevance of the bony labyrinth for investigating fossil primate paleobiodiversity, this article aims to provide additional evidence for assessing the degree of regional variation within Paranthropus through the comparative analysis of the inner ear of DNH 22.
As comparative material, 18 southern African hominin specimens from Sterkfontein, Swartkrans, and Makapansgat (plus published data from Kromdraai B), attributed to Australopithecus, early Homo or Paranthropus, as well as 10 extant human and 10 extant common chimpanzee specimens are investigated. A landmark-based geometric morphometric method is applied for quantitatively assessing labyrinthine morphology. Additionally, cochlear parameters and oval window area are measured.
In terms of semicircular canal and cochlear shape, DNH 22 most resembles the Paranthropus specimen SKW 18 from Swartkrans. Both specimens differ from the other Paranthropus specimens investigated in this study by an anteroposteriorly large posterior semicircular canal and a cochlea with loose turns in the apical portion. Conversely, the oval window area in DNH 22 closely fits the range observed in Paranthropus from Swartkrans and Kromdraai B.
The inner ear of the DNH 22 specimen represents a unique opportunity to provide further insight into the early hominin labyrinthine variation pattern. In particular, the description of DNH 22 raises critical questions on the diversity of the vestibular system and evolutionary pattern of the auditory apparatus in Paranthropus.
自“人类摇篮”最早的发现以来，南非傍人形态变异一直是主要关注点。鉴于骨迷路对于研究化石灵长类古生物多样性的重要性，本文旨在通过对 DNH 22 内耳的比较分析，为评估傍人属内的区域变异程度提供更多证据。
作为比较材料，研究了来自斯特克方丹、斯瓦特克朗斯和马卡潘斯盖特的 18 个南非古人类标本（加上来自克罗姆德莱的已发表数据），这些标本被归因于南方古猿、早期人类或傍人，以及 10 个现生人类和 10 个现生普通黑猩猩标本。采用基于地标点的几何形态测量方法来定量评估迷路形态。此外，还测量了耳蜗参数和卵圆窗面积。
就半规管和耳蜗形状而言，DNH 22 最类似于来自斯瓦特克朗斯的傍人标本 SKW 18。这两个标本与本研究中研究的其他傍人标本在前后方向上的后半规管较大和耳蜗在顶部部分的松散匝数方面存在差异。相反，DNH 22 的卵圆窗面积与在斯瓦特克朗斯和克罗姆德莱 B 发现的傍人属范围内非常吻合。
DNH 22 标本的内耳为进一步深入了解早期人类迷路变异模式提供了独特的机会。特别是，DNH 22 的描述对傍人属前庭系统的多样性和听觉器官的进化模式提出了关键问题。
