A New Carinate Bird from the Late Cretaceous of Patagonia (Argentina)

Abstract
A new bird from the Late Cretaceous of Patagonia (Argentina), known from associated wing elements, is described and its phylogenetic position evaluated. Fossil taxa as well as representatives of species of extant birds sampled from lineages considered to be basal within the crown clade were included in a cladistic analysis of 72 characters primarily from the thoracic limb. Based on the results of the phylogenetic analysis and identification of autapomorphies in the specimen, we name a new taxon Limenavis patagonica. Limenavis patagonica is identified as closer to the crown clade than Enantiornithes by the presence of three unambiguous synapomorphies: a fossa (sometimes with two distinguishable subparts) on the dorsal, distalmost extremity of the humerus; distal fusion of metacarpals II and III; and an extensor process on metacarpal I. It is placed closer to the crown clade than Ichthyornis, and, thus, unambiguously as a carinate (see Methods for terminology), by two further synapomorphies: the ab...