PALEOENVIRONMENTS AND PRESERVATION OF DINOSAUR EGG-BEARING DEPOSITS IN KOREA

Dinosaur eggs with spheroolithids, faveoolithid, and dendroolithid structural types occur in several stratigraphic formations of Cretaceous non-marine deposits in South Korea, the Hasandong Formation at Hadong, the Seonso Conglomerate at Boseong, the Geumnaeri Formation at Gurye, the Haman Formation at Sacheon, the Goseong Formation at Goseong, the Dadaepo Formation at Busan, and the Shiwha Formation at Shiwha. Most of the egg sites are coastal areas except Gurye site, and most of the egg-bearing formations are the Late Cretaceous except the Early Cretaceous Hasandong Formation at Hadong site. Turltle eggs are associated at Boseong and Goseong sites. The dinosaur eggs usually occur as clutches in purple sandy mudstone of floodplain deposits preserved as calcic paleosols with association of vertic paleosol features such as pedogenic slickensides. Some eggs are preserved in gravelly siltstone of channel margin to floodplain deposits at Shiwha site. Most of the eggs are top-broken and filled with surrounding sediments, while some eggs at Boseong site show geoid-fill. The clutch-bearing floodplain deposits occur in various depositional setting from alluvial fan to meandering fluvial plain. The preservation of these dinosaur eggs in calcic and vertic palaeosols suggests that the paleoclimate of the nested areas were semi-arid with alternation of wetting and drying periods. The paleoclimatic condition of Korean dinosaur egg deposits is similar to that of the Late Cretaceous dinosaur egg deposits in Europe, India, North America, and Patagonia. The preservation of numerous dinosaur clutches in several horizons at Boseong and Shiwha sites is consistent with site fidelity. Consequently, dinosaurs nested on diverse environments including alluvial fan, fluvial plain, and channel margin of Korean Peninsula throughout the Cretaceous under semi-arid climate, and the calcareous pedogenesis is deemed to have resulted in the preservation of the dinosaur eggs.