The Carboniferous lungfish genus Sagenodus is reviewed from all available British specimens and described in detail for the first time. We identify two species exclusive to the UK: Sagenodusinaequalis, the type species, deriving from the late Carboniferous (=Pennsylvanian); and Sagenodus quinquecostatus derived from the early Carboniferous (=Mississippian). The genus is probably the most widespread of the known Carboniferous lungfish genera, but the British species have not been formally described since their discovery in the mid–late 19th Century. This work will provide data to help resolve existing questions about the position of Sagenodus in the phylogeny of Palaeozoic lungfishes, and provide a template for the recognition of isolated elements in museum collections and the finds from recent and future field work. The early Carboniferous species, S. quinquecostatus, shows a so far unique functional mechanism in which the lower tooth plates appear to rotate relative to the upper plates during jaw closure, implying a kinetic function at the symphysis or jaw joint.

中文翻译：

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英国石炭纪肺鱼属Sagenodus的系统学和描述

石炭纪肺鱼属鼠尾草属从所有可用的英国标本中回顾并首次详细描述。我们确定了英国独有的两个物种：鼠尾草属不平等，模式种，源自晚石炭纪（=宾夕法尼亚）；和五角鼠尾草源自早石炭纪（=密西西比纪）。该属可能是已知石炭纪肺鱼属中分布最广的属，但自 19 世纪中后期发现英国物种以来，还没有正式描述过。这项工作将提供数据以帮助解决有关鼠尾草属在古生代肺鱼的系统发育中，并为识别博物馆藏品中的孤立元素以及近期和未来实地工作的发现提供了模板。早期石炭纪物种，S. quinquecostatus，显示了迄今为止独特的功能机制，其中下齿板在颌骨闭合期间似乎相对于上板旋转，这意味着在联合或颌关节处具有动力学功能。