Three-dimensional anatomy of the early Eocene Whitephippus (Teleostei, Lampriformes) documents parallel conquests of the pelagic environment by multiple teleost lineages

The early Eocene fossil assemblage of the London Clay (Southeastern England) is a key window to the early Paleogene diversification of teleost fishes in the open ocean. Despite their three-dimensional preservation that offers unique insight into skeletal anatomy, the London Clay fossils are still poorly described for the most part. †Whitephippus tamensis is a fossil teleost from this assemblage, known by several well-preserved specimens. Based on a complete description of the known material, including previously hidden structures (braincase, hyoid, and branchial arches) revealed through 3D microtomography, we reinterpret †Whitephippus as an early member of the teleost group Lampriformes. More specifically, the anatomy of †Whitephippus indicates that it is likely a member of the so-called ‘pelagic clade’ including modern opahs and oarfishes. This redescription of †Whitephippus provides the earliest definitive evidence of lampriforms conquering the pelagic environment, alongside numerous other teleost lineages.