Acanthodes has long been the primary source of information on the pharyngeal skeleton of ‘acanthodians’. Because of this its anatomy has played a disproportionate role in attempts to understand the evolution of the jawed vertebrate pharynx and the clade as a whole. However, the anatomy of the pharynx of Acanthodes, now understood to be a stem-group chondrichthyan, remains poorly characterized and subject to several competing interpretations. We used computed tomography to image the articulated pharyngeal skeletons of three specimens of Acanthodes confusus from Lebach, Germany. Acanthodes has a mélange of osteichthyan-like and chondrichthyan-like morphologies in its pharyngeal skeleton. Like many other chondrichthyans, Acanthodes lacked hypohyals, and had four pairs of posteriorly oriented pharyngobranchials. Like osteichthyans, Acanthodes possessed an interhyal, but lacked the separate infra- and supra-pharyngobranchial elements present in osteichthyans and the crown-chondrichthyan Ozarcus. Using these new data we built and animated a digital 3D model of the pharyngeal endoskeleton in Acanthodes, showing that the jaws could have swung outwards during the opening cycle, increasing the anteriorly facing area of the gape for suspension feeding. These new data provide a more definitive picture of the anatomy of a taxon that has long been of great significance in early vertebrate palaeontology.

中文翻译：

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标志性干群软骨鱼 Acanthodes Agassiz 的咽部，1833 年用微计算机断层扫描技术重新审视


长期以来，棘皮动物一直是“棘皮动物”咽部骨骼信息的主要来源。正因为如此，它的解剖结构在试图理解有颌脊椎动物咽部和整个分支的进化过程中发挥了不成比例的作用。然而，现在被认为是软骨鱼干群的棘齿动物的咽部的解剖结构仍然知之甚少，并且受到多种相互竞争的解释的影响。我们使用计算机断层扫描对来自德国莱巴赫的三个 Acanthodes confusus 标本的铰接咽骨骼进行了成像。棘鱼的咽部骨骼具有类似骨鱼和软骨鱼的混合形态。与许多其他软骨鱼一样，棘鱼缺乏下颚，并且有四对向后定向的咽鳃。与硬骨鱼一样，棘鱼也有间质，但缺乏硬骨鱼和冠软骨鱼 Ozarcus 中存在的独立的咽下和咽上鳃元件。利用这些新数据，我们构建了 Acanthodes 咽部内骨骼的数字 3D 模型并进行了动画处理，表明颌部可能在张开周期中向外摆动，从而增加了张开嘴的前向面积以进行悬浮喂养。这些新数据为分类单元的解剖结构提供了更明确的图景，该分类单元长期以来在早期脊椎动物古生物学中具有重要意义。