Vicariant establishment of Dactylopterus in the western Atlantic linked to shallowing of Central American Seaway (CAS).

Dactylopteridae are marine fishes distributed in tropical and subtropical waters composed of two genera: Dactyloptena, in the Indian Ocean and western and central Pacific Ocean, and Dactylopterus, in the eastern and western Atlantic. Here, we describe the first fossil species from the Atlantic found in the Late Miocene Chagres Formation of Panama. Through morphological comparisons using micro-CT scans and two-dimensional geometric morphometric analysis, we demonstrate that the specimen represents a new species of Dactylopterus. The paleoenvironmental characterization based on petrographic thin sections analyzed using scanning electron microscopy coupled with energy-dispersive spectroscopy (EDS), the geochemical data, and associated microfossil assemblages integrated with an assessment of the environmental data from extant species indicate that this extinct species evolved in a deep-water environment. The finding of †Dactylopterus decrozi n. sp. shows that the genus was already established along the Atlantic margin by the Late Miocene. Current hypotheses propose that dactylopterids colonized the Atlantic through the Tethys Seaway during the Middle Miocene, but our new evidence supports an alternative vicariant scenario associated with the formation of the Panamanian Isthmus. This result is consistent with the previously inferred divergence age of 10.9 Ma that links with the shallowing of the Central American Seaway (CAS).