The early Palaeogene represents a key interval in the evolution of modern marine fish faunas. Together with the first appearances of many familiar fish lineages characteristic of contemporary marine environments, early Palaeogene marine deposits worldwide feature the occurrence of osteoglossid bonytongues. Their presence in marine rocks is surprising, given that these fishes are strictly associated with freshwater environments in modern settings and in other parts of the fossil record. Despite its possible relevance to faunal recovery after the Cretaceous–Palaeogene (K–Pg) extinction, this marine osteoglossid radiation is relatively understudied. Here we describe an osteoglossid specimen from marine Danian deposits of western Greenland (Eqalulik Formation, northern Nuussuaq Peninsula). It consists of disarticulated cranial, pectoral and vertebral material belonging to a relatively large‐bodied predator, similar to the widespread †Brychaetus but with some distinctive features. This specimen expands the geographical range of extinct osteoglossids to the Arctic and represents one of the earliest records of this group in marine deposits. We review other fossil occurrences of marine osteoglossids, highlighting temporal and biogeographical patterns that characterize their rise, diversification and sudden disappearance in the middle Eocene. It is likely that the transition from freshwater to marine environments occurred around the K–Pg boundary, possibly related to ecological replacement of predatory fish lineages that went extinct at the end of the Cretaceous. Further study of the Eqalulik Formation fauna could yield additional insight into the consequences of the end‐Cretaceous extinction with regard to marine fish evolution and the assembly of modern marine faunas.

中文翻译：

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格陵兰Nuussuaq盆地的古新世（Danian）海洋骨g（Teleostei，Osteoglossomorpha），并简要回顾了古近代海洋b鱼

早古生代是现代海洋鱼类动物群进化的关键间隔。加上现代海洋环境中许多熟悉的鱼类谱系的首次出现，全世界早期的古近纪海洋沉积物都具有骨质光泽的ony舌虫的发生。鉴于这些鱼类与现代环境和化石记录其他部分中的淡水环境严格相关，因此它们在海洋岩石中的存在令人惊讶。尽管白垩纪-古近纪（K-Pg）灭绝可能与动物区系恢复有关，但这种海洋骨质放射线的研究相对较少。在这里，我们描述了一个来自格陵兰岛西部（达拉斯半岛北部的Eqalulik组）海洋达尼安沉积的骨光泽标本。它由关节状的颅骨组成，Brychaetus但具有一些鲜明的特征。该标本将已灭绝的骨舌动物的地理范围扩展到了北极，并代表了该组在海洋沉积物中的最早记录之一。我们回顾了海洋化石的其他化石发生，重点介绍了在中始新世中它们的上升，多样化和突然消失的特征的时间和生物地理模式。从淡水到海洋环境的转变很可能发生在K-Pg边界附近，可能与白垩纪末期已灭绝的掠食性鱼类谱系的生态替代有关。对Eqalulik组动物群的进一步研究可能会进一步了解白垩纪末期灭绝对海洋鱼类进化和现代海洋动物群的形成的后果。