Department of Earth Sciences, University of California, Riverside, California 92521.
Integr Comp Biol. 2003 Feb;43(1):219-28. doi: 10.1093/icb/43.1.219.
The increase in trace fossil diversity across the Neoproterozoic-Cambrian boundary often is presented in terms of tabulations of ichnogenera. However, a clearer picture of the increase in diversity and complexity can be reached by combining trace fossils into broad groups defined both on morphology and interpretation. This also focuses attention on looking for similarites between Neoproterozoic and Cambrian trace fossils. Siliciclastic sediments of the Neoproterozoic preserve elongate tubular organisms and structures of probable algal origin, many of which are very similar to trace fossils. Such enigmatic structures include Palaeopascichnus and Yelovichnus, previously thought to be trace fossils in the form of tight meanders.A preliminary two or tripartite terminal Neoproterozoic trace fossil zonation can be be recognized. Possibly the earliest trace fossils are short unbranched forms, probably younger than about 560 Ma. Typical Neoproterozoic trace fossils are unbranched and essentially horizontal forms found associated with diverse assemblages of Ediacaran organisms. In sections younger than about 550 Ma a modest increase in trace fossil diversity occurs, including the appearance of rare three-dimensional burrow systems (treptichnids), and traces with a three-lobed lower surfaces.
穿越新元古代-寒武纪界线的痕迹化石多样性的增加通常以痕迹化石属的列表形式呈现。然而，通过将痕迹化石组合成基于形态和解释定义的广泛类别，可以更清楚地了解多样性和复杂性的增加。这也将注意力集中在寻找新元古代和寒武纪痕迹化石之间的相似性上。新元古代的硅质碎屑沉积物保存了长而管状的生物体和可能是藻类起源的结构，其中许多与痕迹化石非常相似。这些神秘的结构包括 Palaeopascichnus 和 Yelovichnus，以前被认为是紧密弯曲形式的痕迹化石。可以识别出初步的两部分或三部分终端新元古代痕迹化石分带。最早的痕迹化石可能是短的无分枝形式，可能比大约 560 Ma 年轻。典型的新元古代痕迹化石是无分枝且基本上是水平形式的，与多样化的埃迪卡拉生物群组合有关。在比大约 550 Ma 年轻的地层中，痕迹化石的多样性略有增加，包括罕见的三维洞穴系统（ treptichnids ）和具有三叶状下表面的痕迹的出现。
