Dating the 'Taung Child' Australopithecus africanus type specimen through U-Pb measurements of associated calcite crystals

通过相关方解石晶体的 U-Pb 测量测定“Taung Child”南方古猿非洲型标本的年代

• 批准号: NE/H011102/1
• 负责人: Randall Parrish
• 金额: $ 3万
• 依托单位: British Geological Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FH011102%2F1
• 关键词: Dating; Taung; Child; Australopithecus; africanus

The 'Taung Child' was found in 1924 at the Buxton limestone quarry, Northwestern Province, South Africa. The 'Taung Child' was the first early hominid found in Africa and became the type specimen of Australopithecus africanus. Mining activities continued at the quarry and the geological context of the specimen was lost, hampering attempts to date the hominid and understand its ecological context. Because of this, current estimates for the age of the 'Taung Child' range from 3 million to 1 million years old. Such chronological uncertainty greatly hampers our understanding of early hominid evolution in Africa. We propose to take samples of calcite crystals attached to the endocast of the 'Taung Child' and other associated fossils for uranium-lead dating using state-of-the-art facilities at the NERC Isotope Geosciences Laboratory. Pilot evidence demonstrates the suitability of such calcite crystals for high-precision age determination, and permission to sample the calcites has been granted by the Hominid Access Committee. The proposed radiometric dates for the 'Taung Child' are likely to alter the current age-range for Australopithicus africanus, perhaps changing our understanding of ancestor-decendant relationships among early hominin species. The methods undertaken in this study can be applied to other early hominin specimens from the 'Cradle of Humankind' World Heritage Site, South Africa, thereby improving the chronology of human evolution in Africa, and the methods will be refined to maximize the scientific information obtained from the minimum use of valuable fossil material, thereby improving generic methods of analysis of rare and invaluable museum collections.

1924年，在南非西北省巴克斯顿石灰石采石场发现了“Taung Child”。“Taung Child”是在非洲发现的第一个早期人科动物，并成为南方古猿非洲人的模式标本。采石场的采矿活动仍在继续，标本的地质背景已经消失，阻碍了对原始人进行年代测定和了解其生态背景的尝试。正因为如此，目前对“Taung儿童”年龄的估计从300万到100万年不等。这种年代上的不确定性极大地阻碍了我们对非洲早期原始人类进化的理解。我们建议在NERC同位素地球科学实验室使用最先进的设施，对附着在“Taung Child”和其他相关化石内模上的方解石晶体进行铀铅测年。实验证据表明，这种方解石晶体适合于高精度的年龄测定，并允许对方解石进行采样，已获得人科动物访问委员会的批准。“Taung Child”的放射性测定日期可能会改变目前南方古猿非洲人的年龄范围，也许会改变我们对早期人类物种之间祖先关系的理解。本研究中采用的方法可以应用于南非“人类摇篮”世界遗产地的其他早期人类标本，从而改进非洲人类进化的年表，并将改进方法，以最大限度地利用最少的有价值的化石材料获得科学信息，从而改进稀有和宝贵的博物馆收藏品的通用分析方法。