FIRST REPORT OF SPECIFIC BIRD FEEDING TRACES––PROBE AND PECK MARKS––FROM THE LOWER CRETACEOUS HAMAN FORMATION, SOUTH KOREA

A variety of avian feeding traces have been reported from the fossil record. Probe marks have been reported from the Upper Cretaceous Cantwell Formation in Alaska, USA, and the Santo Domingo Formation in Argentina, although the latter is poorly described, illustrated, and interpreted. Dabble marks have been reported from the Eocene Green River Formation of Utah, USA. Spoonbill-like feeding behaviors have previously been reported from the Haman Formation. Peck marks, however, have not been reported previously. Modern peck marks have been described from marine and continental settings. Two specimens from the Lower Cretaceous Haman Formation, South Korea near Jinju, South Korea, have a number of simple surface trace fossils associated with bird tracks attributable to Koreanornis hamanensis and Koreanornis isp. Invertebrate traces Cochlichnus, Steinichnus, and Arenicolites are also associated with the bird tracks and simple traces. These simple traces consist of elongate, tapered convex traces and double-oval convex traces. Simple elongate traces are interpreted as peck marks alongside concentrated areas of bird tracks attributed to Koreanornis hamanensis. Double-oval marks are interpreted as probe marks alongside isolated tracks. There are two distinguishable types of probe marks: large and small. There is a single large probe mark, 6.9 mm long and 2.9 mm wide. The two smaller probe marks are 4.5 mm long and 2.2 mm wide and 5.7 mm long and 3.0 mm wide, respectively. Peck marks range from 4.0 mm to 11.2 mm long and average 7.6 mm wide. The two distinct morphologies of probe marks may represent different species of probing birds or a single species of bird probing at a different speed or angle. The presence of both probe and peck marks indicates at least two different species of bird present. The presence of modern-like avian feeding behaviors in an environment ~110 million years ago suggests that Early Cretaceous ornithurine birds were highly advanced.