Abstract:
The fossil tropicbird Heliadornis ashbyi Olson, previously known from the unique holotype from the middle Miocene Calvert Formation of Maryland, is here recorded from a contemporaneous site in Belgium based on a nearly complete humerus. Its trans-Atlantic occurrence at a much higher latitude suggests that Heliadornis may have been the higher-latitude sister group of the extant tropical genus Phaethon, much as within the Sulidae gannets of the genus Morus are the higher latitude counterparts of the tropical boobies of the genus Sula.
