Borings in Cloudina shells:: Complex predator-prey dynamics in the terminal neoproterozoic
Borings in Cloudina shells:: Complex predator-prey dynamics in the terminal neoproterozoic
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DOI：
10.1669/0883-1351(2003)018
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发表时间：
2003-10-01
期刊：
影响因子：
1.6
通讯作者：
Zhang, LY
中科院分区：
文献类型：
--
作者：
Hua, H;Pratt, BR;Zhang, LY
长期以来，人们一直认为捕食是进化变化的重要驱动力，尽管很难用捕食相互作用的具体例子来证实这一点，特别是对于动物生命的早期古生代多样化而言。这项研究证实了中国新元古代最上部存在钻贝捕食现象。最早的矿化动物之一——克劳迪娜（Cloudina）的近百个管状贝壳中，近五分之一的贝壳都被宽度为 15-85 微米的掠食性钻孔所穿孔。相比之下，属于Sinotubulites的共存贝壳样本没有受到影响。捕食者的身份仍然难以捉摸，但钻孔大小的变化表明，在其达到最小尺寸后，在其整个生长过程中都存在捕食性生活方式。钻孔距贝壳孔的距离相对均匀，表明要么受到贝壳生命方向（例如沉积物表面的位置）的控制，要么更可能是捕食者对位于孔附近的保护措施的回避反应。假设Sinotubulites具有相似的生活习性并且是潜在的猎物，那么该分类单元中没有钻孔就证明这些管可能受到有机物质或毒素的保护，从而抵御了钻壳捕食者。因此，化石记录中这个最早的捕食例子已经显示了猎物选择性和特定地点的行为，表明前寒武纪捕食者与猎物相互作用的水平接近于较年轻的古生代底栖动物群落的复杂性。这与捕食确实是寒武纪辐射的积极贡献者的建议是一致的。
Predation as an important driver of evolutionary change long has been assumed, despite difficulties to substantiate it with specific examples of predatory interaction, especially for the early Paleozoic diversification of animal life. This study corroborates the existence of shell-drilling predation in the uppermost Neoproterozoic of China. Nearly one-fifth of almost one hundred tubular shells of one of the earliest mineralized animals, Cloudina, are perforated by undoubted predatory borings 15-85 mum wide. By contrast, no specimens of co-occurring shells belonging to Sinotubulites were affected. The identity of the predator remains elusive, but variation in size of the borings suggests a predatory lifestyle throughout its growth, after it reached a minimum size. The relatively uniform distance of he borings from the shell apertures points to either control by the life orientation of the shells, such as the position of the sediment surface, or, more likely, an avoidance response by the predator to protective measures located near the aperture. Assuming Sinotubulites had similar life habits and was potential prey, the absence of borings in this taxon is evidence that these tubes may have been protected by organic material or toxins that fended off shell-drilling predators. Hence this earliest example of predation in the fossil record already shows prey selectivity and site-specific behavior, pointing to a level of Precambrian predator-prey interaction that approaches the complexity seen in younger Paleozoic benthic animal communities. This is consistent with the suggestion that predation was indeed an active contributor to the Cambrian radiations.