Osteoglossid bonytongues (arapaimas, arowanas, and relatives) are extant tropical freshwater fishes with a relatively abundant and diverse fossil record. Most osteoglossid fossils come from a 25-million-year interval in the early Palaeogene, when these fishes were distributed worldwide in both freshwater and marine environments. Despite their biogeographic and palaeoecological relevance, and a relative abundance of well-preserved material, the evolutionary relationships between these Palaeogene forms and extant bonytongues remain unclear. Here we describe a new genus of bonytongue from early Eocene marine deposits of Morocco, represented by an articulated, three-dimensionally preserved skull with associated pectoral girdle. This taxon is characterized by an elongated snout, contrasting with the short jaws usually found in marine representatives of the clade. A revision of morphological characters in bonytongues allows us to place this new genus, together with other marine and freshwater Eocene taxa, within crown osteoglossids and closely related to extant arapaimines. The discovery of the new Moroccan taxon hints at a previously underestimated eco-morphological diversity of marine bonytongues, highlighting the diverse trophic niches that these fishes occupied in early Palaeogene seas.

中文翻译：

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摩洛哥始新世早期的长吻海洋骨舌动物（Teleostei：Osteoglossidae）以及海洋骨舌动物的系统发育亲缘关系

骨舌骨舌鱼（巨骨舌鱼、龙鱼及其近亲）是现存的热带淡水鱼，拥有相对丰富且多样化的化石记录。大多数骨舌鱼化石来自古近纪早期 2500 万年的时间间隔，当时这些鱼类分布在世界各地的淡水和海洋环境中。尽管它们具有生物地理学和古生态学的相关性，并且保存完好的材料相对丰富，但这些古近纪形式与现存骨舌之间的进化关系仍不清楚。在这里，我们描述了来自摩洛哥始新世早期海洋沉积物的一个新属的骨舌，其代表是一个铰接的、三维保存的头骨和相关的胸带。该分类群的特征是鼻子细长，与该分支的海洋代表中通常发现的短下颌形成鲜明对比。对骨舌动物形态特征的修改使我们能够将这个新属与其他海洋和淡水始新世类群一起放置在冠骨舌科中，并与现存的巨骨舌鱼密切相关。摩洛哥新分类群的发现暗示了以前低估的海洋骨舌鱼的生态形态多样性，突显了这些鱼类在古近纪早期海洋中占据的多样化营养生态位。