A new Coraciiformes (Aves, Coraciimorphae) from the Eocene of Chubut province, Argentinean Patagonia

POL, D.; DEGRANGE, F.J.

La Plata

Congreso; Reunión de Comunicaciones de la Asociación Paleontológica Argentina 2019; 2019

Coraciiformes (bee-eaters, rollers, andkingfishers) is a group of Neognathae that includes colorful and excellentflyers birds that live in diverse habitats, ranging from open savannas to riverdales. Although highly diverse and worldwide distributed in the present, the fossilrecord of Coraciiformes is scarce in Europe and North America and null in SouthAmerica. Here we present the first record of a Coraciiformes proceeding from theLaguna del Hunco Formation (early Eocene). This formation is characterized by itsdiverse assemblage of fossils plants, inferred to represent lakeshorevegetation. The specimen MPEF-PV 10991 consists of a right incomplete hind limbthat presents the following combination of characters, characteristic ofCoraciiformes: relatively short and stout tibiotarsus, poorly developed cristaecnemialis, short and wide tarsometatarsus, with the tuberositas m. tibialiscranialis located medially on the shaft, and a curved and stout ungual phalanx.Moreover, the presence of a rounded and conspicuous foramen vascularedistale and the trochlea metatarsi II strongly directed medially suggests the specimenmay be more related to Alcedinidae (kingfishers) than to other coraciiformgroups. The new specimen is the oldestsubstantial record of Coraciiformes outside Europe and North America,indicating that this clade had a more widespread distribution than previouslyhypothesized, extending its geographical range into the Southern Hemispherealready by the early Eocene. The new material can provide new morphologicaldata for understanding the evolutionary origin and radiation of Coraciiformesand important data for calibrating molecular clockestimates of the divergence time of this clade.