Narrow-beaked trogons from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK)

Abstract

AbstractWe describe multiple partial skeletons of a new trogon species from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK), which are among the oldest fossils of the Trogoniformes.Eotrogon stenorhynchus, gen. et sp. nov. has a much narrower and more gracile beak than extant trogons, which denotes different ecological attributes of the fossil species.Eotrogon stenorhynchusalready had the heterodactyl foot characterising extant trogons, even though the trochlea for the second toe is smaller than in crown group Trogoniformes. Differences to extant trogons in the wing and pectoral girdle elements suggest thatE. stenorhynchuswas less adapted to short-term hovering, which may indicate different foraging techniques. We also report a partial tarsometatarsus from the early Miocene of France that is likely to belong toParatrogon gallicus, a species previously only known from humeri.P. gallicusis the earliest modern-type trogon, and we show that the newly identified tarsometatarsus does not support the proposed referral of this species to the African taxonApaloderma. We identify skeletal features that suggest a sister group relationship betweenApalodermaand all other crown group Trogoniformes, but the exact affinities ofParatrogonremain poorly resolved. (http://zoobank.org/urn:lsid:zoobank.org:pub:73B64B84-11C2-4D50-8540-099CF86B6CA1).