School of Earth Sciences and Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK.
School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham B15 2TT, UK.
Proc Biol Sci. 2021 Jul 28;288(1955):20211176. doi: 10.1098/rspb.2021.1176. Epub 2021 Jul 21.
Radiodonts evolved to become the largest nektonic predators in the Cambrian period, persisting into the Ordovician and perhaps up until the Devonian period. They used a pair of large frontal appendages together with a radial mouth apparatus to capture and manipulate their prey, and had evolved a range of species with distinct appendage morphologies by the Early Cambrian (approx. 521 Ma). However, since their discovery, there has been a lack of understanding about their basic functional anatomy, and thus their ecology. To explore radiodont modes of feeding, we have digitally modelled different appendage morphologies represented by , , and from the Burgess Shale. Our results corroborate ideas that there was probably a significant (functional and hence behavioural) diversity among different radiodont species with adaptations for feeding on differently sized prey (0.07 cm up to 10 cm). We argue here that appendages were suited for feeding on suspended particles rather than filtering sediment. Given the limited dexterity and lack of accessory feeding appendages as seen in modern arthropods, feeding must have been inefficient and 'messy', which may explain their subsequent replacement by crown-group arthropods, cephalopods and jawed vertebrates.
放射虫进化为寒武纪时期最大的游泳掠食者，一直延续到奥陶纪，也许直到泥盆纪。它们使用一对大的额前附肢和一个辐射状的口器来捕捉和操纵猎物，并在早寒武纪（约 5.21 亿年前）进化出了一系列具有明显附肢形态的物种。然而，自从它们被发现以来，人们对它们的基本功能解剖结构及其生态了解甚少。为了探索放射虫的摄食方式，我们对来自伯吉斯页岩的 、 、 和 等不同形态的附肢进行了数字建模。我们的研究结果证实了这样一种观点，即不同的放射虫物种之间可能存在显著的（功能上的，因此也是行为上的）多样性，它们适应于捕食不同大小的猎物（0.07 厘米至 10 厘米）。我们在这里认为， 附肢适合于摄食悬浮颗粒，而不是过滤沉积物。鉴于现代节肢动物的附肢灵巧性有限，且缺乏辅助摄食的附肢，摄食效率必然很低，而且“一团糟”，这也许可以解释它们后来为何被冠群节肢动物、头足类动物和有颌脊椎动物所取代。
