Flamingo and duck‐like bird tracks from the Late Cretaceous and early Tertiary: Evidence and implications

Two new Late Cretaceous ichnospecies are named on the basis of tracks of birds with webbed feet discovered in the Uhangri Formation, Hwangsan Basin of South Korea. The first, Uhangrichnus chuni ichnogen. et ichnosp. nov., is based on a large sample of small tracks, whereas the second, Hwangsanipes choughi ichnogen. et. ichnosp. nov., is based on a single trackway of a larger bird from the same stratigraphie level. The tracks form part of a high density track assemblage in lacustrine shoreface sediments and are the oldest traces of web‐footed birds so far reported.

A third, Early Tertiary ichnospecies, Presbyorniformipes feduccii ichnogen. et ichnosp. nov., is named on the basis of trackways and feeding trails of a bird with webbed feet from the Early Eocene Green River Formation of eastern Utah. This previously unnamed track type has already been attributed to the Eocene shorebird Presbyornis and cited as an example of trace‐fossil evidence for feeding behavior in a lakeshore setting. Although this attribution is not proven, we consider it reasonable and note that P. feduccii occurs in association with a diverse assemblage of bird tracks attributable to other, quite different, shorebirds.

Both the Late Cretaceous and Early Tertiary track evidence is consistent with hypotheses that suggest that a Late Cretaceous flamingo‐like stock gave rise to duck‐like species in the early Tertiary.