Bowring S A, Grotzinger J P, Isachsen C E, Knoll A H, Pelechaty S M, Kolosov P
Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge 02139, USA.
Science. 1993 Sep 3;261:1293-8. doi: 10.1126/science.11539488.
An explosive episode of biological diversification occurred near the beginning of the Cambrian period. Evolutionary rates in the Cambrian have been difficult to quantify accurately because of a lack of high-precision ages. Currently, uranium-lead zircon geochronology is the most powerful method for dating rocks of Cambrian age. Uranium-lead zircon data from lower Cambrian rocks located in northeast Siberia indicate that the Cambrian period began at approximately 544 million years ago and that its oldest (Manykaian) stage lasted no less than 10 million years. Other data indicate that the Tommotian and Atdabanian stages together lasted only 5 to 10 million years. The resulting compression of Early Cambrian time accentuates the rapidity of both the faunal diversification and subsequent Cambrian turnover.
在寒武纪初期发生了一次生物多样性的爆发事件。由于缺乏高精度年代测定，寒武纪的进化速率一直难以准确量化。目前，铀铅锆石地质年代学是测定寒武纪岩石年代最有效的方法。来自西伯利亚东北部下寒武统岩石的铀铅锆石数据表明，寒武纪始于约5.44亿年前，其最古老的（曼凯阶）阶段持续不少于1000万年。其他数据表明，托莫特阶和阿特达板阶加起来仅持续了500万至1000万年。早寒武世时间的这种压缩凸显了动物群多样化和随后寒武纪更替的快速性。
