Abstract A detailed description of the caudal skeleton of the Paleogene nasine surgeonfish Arambourgthurus scombrurus is provided herein. The compound (urostylar) centrum is fused with a large, nearly triangular, thick hypural plate, formed by consolidated hypurals 1–4. The compound centrum supports a large autogenous parhypural bearing a thick and blunt hypurapophysis. Hypural 5 is a small triangular bone. There is a single elongate autogenous uroneural and three epurals, the first of which is remarkably stout and elongate, with its proximal end embraced by the open neural arch of the second preural vertebra. The haemal spines of the second and third preural vertebrae are fused to their respective centra. The phylogenetic relationships of Arambourgthurus are discussed. Arambourgthurus shares some features with the Eocene Sorbinithurus and the Miocene Marosichthys, and together they constitute a monophyletic group that represents the sister group of the pair formed by the extant genus Naso and the fossil genus Eonaso. The overall structure of the caudal propulsive unit bears a strong resemblance to that of Luvarus and some of its closely related fossil taxa, and this suggests that Arambourgthurus scombrurus most likely had an oceanic habitat in the epipelagic zone.

中文翻译：

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Arambourgthurus scombrurus () 的尾骨骨骼，一种古近纪海洋刺尾鱼

摘要 本文提供了古近纪鼻刺尾鱼 Arambourgthurus scombrurus 尾骨骨骼的详细描述。复合（urostylar）中心与大的、近三角形的、厚的hypural板融合，由固结的hypurals 1-4形成。复合中心支撑着一个带有厚而钝的骨突的大型自体骨突。Hypural 5 是一个小的三角形骨头。有一个细长的自体泌尿神经和三个外膜，第一个非常粗壮和细长，其近端被第二前椎骨的开放神经弓包围。第二和第三前椎骨的血棘与它们各自的中心融合。讨论了 Arambourgthurus 的系统发育关系。Arambourgthurus 与始新世 Sorbinithurus 和中新世 Marosichthys 共享一些特征，它们共同构成一个单系群，代表现存的 Naso 属和化石 Eonaso 属形成的一对姐妹群。尾部推进装置的整体结构与 Luvarus 及其一些密切相关的化石分类群非常相似，这表明 Arambourgthurus scombrurus 最有可能在上层海区拥有海洋栖息地。