遗迹歧异度（ichnodisparity）：另眼看寒武纪生命大爆发

遗迹歧异度作为评估生物成因构造中形态轮廓变化的概念被引入,它揭示出造迹生物个体轮廓、运动系统和行为过程的主要创新。遗迹歧异度是基于形态结构设计的测量鉴别,而遗迹多样性是指遗迹分类的数量,即遗迹属或遗迹种的数量。本文统计前寒武纪-寒武纪之交(埃迪卡拉纪和寒武纪纽芬兰世、第二世)的88个遗迹属,并鉴定出40个形态结构设计类型,其中前寒武纪包含22个形态结构设计类型,遗迹多样性为32;寒武纪遗迹形态结构设计类型为38个,遗迹多样性为82。前寒武纪-寒武纪之交的遗迹化石资料显示,埃迪卡拉纪和寒武纪幸运期之交是遗迹多样性与遗迹歧异度的突变期,两者数量均显著增加。这表明造迹生物在数量上急剧增加,在形态类型上更加多样,造迹生物的个体轮廓、运动方式以及行为过程都渐趋复杂、多样,有力地支持了寒武纪生命大爆发事件。遗迹歧异度和遗迹多样性相结合,将会进一步增强遗迹学在演化古生物学中的重要性。

ICHNODISPARITY: ANOTHER VIEW OF CAMBRIAN EXPLOSION

Ichnodisparity has been recently introduced as a concept to assess the variability of morphologic plans, revealing major innovations in body plan, locomotive system and behavior patterns. Ichnodisparity is evaluated based on the identification of categories of architectural design, whereas ichnodiversity is measured in terms of the number of ichnotaxa (i.e. ichnogenera and/or ichnospecies).This study summarizes ninety ichnogenera and identifies forty architectural designs during the Precambrian-Cambrian transition (Ediacaran, Terreneuvian, Epoch 2). There are 22 architectural designs and 32 ichnogenera found in the Ediacaran, and 38 architectural designs and 84 ichnogenera for the Terreneuvian and Epoch 2 of Cambrian.Trace fossil data of the Precambrian-Cambrian transition reveals that ichnodisparity and ichnodiversity both expanded during this period. The significant increase in ichnodisparity and ichnodiversity in the Precambrian-Cambrian transition, reveals that the variety and numbers, body plans, locomotive modes and the complexity of behavior processes of organisms have increased dramatically in the Cambrian, which effectively support the Cambrian explosion event from the ichnological evidences. Combining the studies of ichnodisparity and ichnodiversity will further enhance the significance of ichnology in thestudy of evolutionary paleontology.