Data from: Trends in shell fragmentation as evidence of mid- Paleozoic changes in marine predation

Recent observations indicate that shell fragmentation can be a useful tool in assessing crushing predation in marine communities. However, criteria for recognizing shell breakage caused by durophagous predators versus physical factors are still not well established. Here, we provide data from tumbling and aquarium experiments to argue that physical and biotic processes lead to different patterns of shell damage, specifically that angular shell fragments are good indicators of durophagous predation. Using such angular shell fragments as a predation proxy, we analyze data from 57 European Paleozoic localities spanning the Ordovician through the Mississippian. Our results reveal a significant increase in angular shell fragments (either occurring as isolated valves or present in regurgitalites) in the Mississippian. The timing of this increase is coincident with the increased diversity of crushing predators as well as marked anti- predatory changes in the architecture and mode of life of invertebrate prey observed after the end-Devonian Hangenberg extinction (359 Ma). More specifically, the observed trend in shell fragmentation constitutes strong and independent confirmation of a recently suggested end-Devonian changeover in the primary method of fish predation from shearing to crushing. These results also highlight the important effect of extinction events, not only on taxonomic diversity, but also on the nature of predator-prey interactions.

近期观测研究显示，壳体破碎分析可成为评估海洋群落中粉碎型捕食（crushing predation）的有效手段。然而，区分由食壳性捕食者（durophagous predator）造成的壳体破损与物理因素导致的破损的判别标准，目前仍未得到充分确立。本研究通过翻滚实验与水族箱实验获取的数据，证明物理过程与生物过程会形成不同的壳体破损模式，具体而言，带棱角的壳体碎片可作为食壳性捕食的良好指示标志。本研究以这类带棱角的壳体碎片作为捕食作用替代指标，对57处欧洲古生代产地的数据展开分析，这些产地的地质时代覆盖奥陶纪至密西西比纪。研究结果显示，密西西比纪地层中带棱角的壳体碎片（包括以孤立壳瓣形式存在的碎片，或是存在于反流粪化石（regurgitalites）中的碎片）的占比显著上升。该占比上升的时间节点，与粉碎型捕食者多样性的增加，以及泥盆纪末亨根贝格灭绝事件（End-Devonian Hangenberg extinction，359 Ma）后观测到的无脊椎猎物的壳体结构与生活方式的显著反捕食演化特征相吻合。更具体地说，本次观测到的壳体破碎趋势，为近期提出的‘泥盆纪末鱼类捕食主要方式从剪切型向粉碎型转变’的假说提供了强有力的独立佐证。本研究结果同时凸显了灭绝事件的重要影响：其不仅会影响类群多样性，还会改变捕食者与猎物间的相互作用本质。