Geosciences Department, Williams College, Williamstown, MA 01267, USA.
Department of Earth Sciences, Dartmouth College, Hanover, NH 03755, USA.
Sci Adv. 2017 Jun 28;3(6):e1700095. doi: 10.1126/sciadv.1700095. eCollection 2017 Jun.
Biomineralization marks one of the most significant evolutionary milestones among the Eukarya, but its roots in the fossil record remain obscure. We report crystallographic and geochemical evidence for controlled eukaryotic biomineralization in Neoproterozoic scale microfossils from the Fifteenmile Group of Yukon, Canada. High-resolution transmission electron microscopy reveals that the microfossils are constructed of a hierarchically organized interwoven network of fibrous hydroxyapatite crystals each elongated along the [001] direction, indicating biological control over microstructural crystallization. New Re-Os geochronological data from organic-rich shale directly below the fossil-bearing limestone constrain their age to <810.7 ± 6.3 million years ago. Mineralogical and geochemical variations from these sedimentary rocks indicate that dynamic global marine redox conditions, enhanced by local restriction, may have led to an increase in dissolved phosphate in pore and bottom waters of the Fifteenmile basin and facilitated the necessary geochemical conditions for the advent of calcium phosphate biomineralization.
生物矿化是真核生物进化历程中的一个重要里程碑，但它在化石记录中的起源仍不清楚。我们报告了在加拿大育空地区 15 英里组的新元古代尺度微化石中存在受控制的真核生物生物矿化的结晶学和地球化学证据。高分辨率透射电子显微镜揭示，这些微化石由纤维状羟磷灰石晶体的分层交织网络构成，每个晶体都沿[001]方向拉长，表明对微观结构结晶具有生物控制。来自化石层下方富含有机质页岩的新的 Re-Os 年代学数据将其年龄限定在<810.7 ± 6.3 百万年前。这些沉积岩的矿物学和地球化学变化表明，动态的全球海洋氧化还原条件，加上局部限制，可能导致 15 英里盆地的孔隙和底部水中溶解磷酸盐增加，并为磷酸钙生物矿化的出现创造了必要的地球化学条件。
