Department of Anatomy, Midwestern University, IL, USA; Evolutionary Studies Institute and Centre for Excellence in PalaeoSciences, University of the Witwatersrand, South Africa.
Department of Biological Sciences, Marshall University, WV, USA; Human Origins Program, National Museum of Natural History, Smithsonian Institution, DC, USA.
J Hum Evol. 2018 Dec;125:181-192. doi: 10.1016/j.jhevol.2017.06.013.
KNM-ER 47000A is a new 1.52 Ma hominin scapular fossil belonging to an associated partial skeleton from the Koobi Fora Formation, Kenya (FwJj14E, Area 1A). This fossil effectively doubles the record of Early Pleistocene scapulae from East Africa, with KNM-WT 15000 (early African Homo erectus) preserving the only other known scapula to date. KNM-ER 47000A consists of a complete glenoid cavity preserving a portion of the scapular spine and neck, the proximal half of the acromion, and a majority of the axillary border. A sufficient amount of anatomy is preserved to compare KNM-ER 47000A with scapulae of several Australopithecus species, extinct Homo, and living hominoids. The glenohumeral joint of KNM-ER 47000A is more laterally oriented than those of great apes and Australopithecus, aligning it closely with KNM-WT 15000 and modern humans. While this morphology does not imply a strong commitment to arboreality, its scapular spine is obliquely oriented-as in gorillas and some Australopithecus fossils-particularly when compared to the more horizontal orientation seen in KNM-WT 15000 and modern humans. Such a spine orientation suggests a narrow yet long infraspinous region, a feature that has been attributed to suspensory taxa. Accordingly, the morphology of KNM-ER 47000A presents conflicting behavioral implications. Nonetheless, a multivariate consideration of the available scapular traits aligns KNM-ER 47000A and Australopithecus with great apes, whereas KNM-WT 15000 resembles modern humans. The scapular morphology of KNM-ER 47000A is unique among fossil and extant hominoids and its morphological differences from KNM-WT 15000 strengthen the attribution of KNM-ER 47000 to Paranthropus boisei as opposed to early Homo. As the first evidence of scapular morphology in P. boisei, KNM-ER 47000A provides important new information on variation in hominin shoulder and upper limb anatomy from this critical period of hominin evolutionary history.
KNM-ER 47000A 是一种新的 1.52 万年前的人类肩胛骨化石，属于肯尼亚库比福拉地层（FwJj14E，1A 区）的一个相关部分骨架。该化石将东非早更新世肩胛骨的记录有效地翻了一番，而 KNM-WT 15000（早期非洲直立人）则保存了迄今为止唯一已知的肩胛骨。KNM-ER 47000A 由一个完整的关节盂腔组成，其中包含一部分肩胛骨脊柱和颈部、肩峰的近端一半以及大部分腋窝边界。保存的解剖结构足以将 KNM-ER 47000A 与几种南方古猿物种、已灭绝的人类和现存的人科动物的肩胛骨进行比较。KNM-ER 47000A 的盂肱关节比类人猿和南方古猿更偏向外侧，与 KNM-WT 15000 和现代人非常接近。虽然这种形态结构并不意味着对树栖生活有强烈的适应性，但它的肩胛骨脊柱呈倾斜状，就像大猩猩和一些南方古猿化石一样，尤其是与 KNM-WT 15000 和现代人中更为水平的方向相比。这种脊柱的方向表明存在一个狭窄但较长的肩胛下窝区域，这一特征被归因于悬挂类人猿。因此，KNM-ER 47000A 的形态结构提出了相互矛盾的行为意义。尽管如此，对现有肩胛骨特征的多变量考虑将 KNM-ER 47000A 和南方古猿与类人猿联系在一起，而 KNM-WT 15000 则与现代人相似。KNM-ER 47000A 的肩胛骨形态在化石和现存人科动物中是独一无二的，它与 KNM-WT 15000 的形态差异加强了将 KNM-ER 47000A 归因于粗壮南猿而不是早期人类的观点。作为粗壮南猿肩胛骨形态的第一个证据，KNM-ER 47000A 为这个人类进化历史的关键时期提供了关于人肩和上肢解剖结构变异的重要新信息。
