Waterbird foraging traces from the early Eocene Green River Formation, Utah

Abstract Foraging traces associated with the web-footed avian footprint ichnotaxon Presbyornithiformipes feduccii are described. Four new ichnospecies in three new ichnogenera are established to identify and describe the traces that resulted from foraging behaviors. All four ichnotaxa are, in places, overprinted by P . feduccii footprints and occur either laterally to, or sinuously woven between, P . feduccii trackways and therefore were clearly emplaced by the P . feduccii tracemaker. Erevnoichnus blochi new ichnogenus new ichnospecies is established for a series of pits, joined by a marginal groove, that are associated with web-footed bird trackways. This ichnotaxon is interpreted to record regular probing/gaping as a waterbird swept its head from side to side searching for food. Erevnoichnus strimmena n. igen. new ichnospecies is established for en-echelon, gently arcuate grooves produced through forward probing by a waterbird searching for food. Ravdosichnus guntheri new ichnogenus new ichnospecies is established for simple grooves with u-shaped profiles produced when a waterbird dragged its bill backwards through the sediment. Aptosichnus diatarachi new ichnogenus new ichnospecies is established for a broad, shallow groove/trough characterized by sinuous margins and a complex, irregular fill. It is interpreted to record thorough bill stirring in an area with common prey. All four ichnotaxa named herein are interpreted to record tactile feeding behavior by a marginal lacustrine waterbird searching for prey. Their association with Presbyornithiformipes feduccii suggests that the purported tracemaker, Presbyornis pervetus , did not forage solely through filter-feeding but was also capable of tactile foraging for larger prey. UUID: www.zoobank.org/42c5d24b-6e9a-45da-9a48-78f8f040311c