The description of the Flat fish (Pleuronectiformes) Fossils from the Miocene Duho Formation, Pohang Yeonam-dong in Korea and its Implication

Abstract

Four entities of the Cenozoic fish fossils were discovered in the Miocene Duho Formation, Pohang, Korea. these fossils were identified as the first Pleuronectiformes in Korea based on the following-the presence of postcleithrum, the elongation of the first proximal pterygiophore of the anal fin ray, almost consistent presence of two proximal pterygiophore of the anal fin rays between the two adjacent hemal spines, the fusion of the first and second hypurals, the fusion of the third and fourth hypurals and the first preural centrum, the presence of well-developed anteriormost plate-like neural spine, the presence of the urohyal like fish-hook and its elongated sciatic part, and the division of the parahypural from the first preural centrum. On the other hand, geological studies about the Duho Formation consistently claimed that shallow-sea creatures were washed away by meteorological events such as a great flood and deposited at the bottom of deep-sea by the turbidity current. However, in Duho Formation, only shallow-sea ones have been discovered thus far. This study reported that Flat fish, deep-sea creature, was discovered in Duho Formation for the first time in Korea.