Early Cretaceous freshwater fishes from Japan and Korea

Abstract

The Early Cretaceous freshwater fish assemblages found in the Wakino Subgroup in northern Kyushu, Japan and the Nagdong Subgroup in southern Korea are the same in age, but different in depositional environment, because there is a common species, Wakinoichthys aokii, but other fishes differ. The Nagdong Subgroup was probably deposited near the sea, because of the existence of elopiform and albuiform fishes. The age of both subgroups may be slightly older than that of the localities of the Mesoclupea-Paralycoptera assemblage in southern China. The fish fossils from the Tetori Group are unique, somewhat earlier, and may support the gradual Jurassic-Cretaceous faunal transition hypothesized from the reptilian fossils, although evidence from these fish fossils is insufficient to confirm or deny the hypothesis.