Multi-Aged Small Pterosaur Track Assemblage from the Upper Cretaceous of Korea

Abstract

The pterosaur is the earliest and largest powered flying vertebrate, even earlier and larger than the other extant archosaurian group, birds. However, evidence for this flying reptile, including the diversity of the small-sized pterosaur after the mid-Cretaceous, and their ecology, has remained elusive. Here we present numerous and dense pterosaur track assemblages from the Hwasun Seoyuri tracksite in the Upper Cretaceous Jangdong Formation of the Neungju Basin in Korea. The pterosaur track assemblage, assigned to Pteraichnus isp., consists of various sized, randomly oriented manus-dominated tracks with several pes claw marks. These features commonly indicate the semi-aquatic behavior and multi-age gregariousness of pterosaurs. The supposed trackmaker of pterosaur tracks would be the small-sized pterodactyloid that inhibited the Late Cretaceous Korean Peninsula, but that has not previously been reported. This ichnological evidence for the global distribution of small-sized pterosaurs could be interpreted to mean that the pterosaur fauna in the Late Cretaceous was more distributed and diverse than was previously known.