New pterosaur tracks from the Hasandong Formation (Lower Cretaceous) of Hadong County, South Korea

摘要

In 2004, fifty new pterosaur tracks were discovered in the Hasandong Formation (Lower Cretaceous), South Korea. They are preserved as natural casts on the surface of an isolated dark grey mudstone block (70 x 50 cm). Manus and pes imprints are very small, averaging 25.6 mm and 25.7 mm long, respectively. The manus imprints (N = 25) are tridactyl and digit 1, 11, Ill are strongly asymmetric. Fully plantigrade pes imprints (N = 25) were left by elongate metatarsals with short four digits (the ratio of digit to whole pes length is 2.6). There is no trace of the 5th phalanx of the pes. As these features clearly distinguish the Hadong tracks from the type species of the ichnogenus Pteraichnus, we assign them to a new species, Pteraichnus koreanensis. They are stratigraphically the oldest pterosaur tracks in Korea and are distinguished by size and morphology from the two pterosaur ichnotaxa, Haenamichnus uhangriensis and Pteraichnus isp., previously reported from the Uhangri and Haman formations. Pteraichnus koreanensis is the smallest pterosaur track currently reported from Asia.