Time, Space and Structure on the Korea Cretaceous Dinosaur Coast: Cretaceous Stratigraphy, Geochronology, and Paleoenvironments

Abstract

The stratigraphy, geological ages, and paleoenvironments of the Korea Cretaceous Dinosaur Coast (KCDC) are reviewed and synthesized in order to understand the occurrence and diversity of the vertebrate fossils and track remains in time and space. Various absolute age measurements obtained during the last decade yield new age data to correlate with the dinosaur fossil-bearing Cretaceous deposits in Korea. The radiometric age of the lower (Sindong Group) and middle (Hayang Group) parts of the Gyeongsang Basin (the largest basin of the KCDC) located in the eastern part of the KCDC gives dates ranging from Aptian to Campanian, which is younger than the previous biostratigraphic age estimates, but the results may be influenced by metamorphism. Likewise, radiometric dates from the Cretaceous sequence in the western part of the KCDC give numerical values suggesting a correlation with the Upper Cretaceous Yucheon Group of the Gyeongsang Basin. Dinosaur evidence (e.g., tracks, eggs, bones) along the KCDC is variable in relation to stratigraphy and paleoenvironment. Dinosaur tracks are preserved mostly in stratigraphically higher Cretaceous lake margin deposits, whereas dinosaur bones occur mostly in older Cretaceous floodplain deposits. Most dinosaur eggs are found in Upper Cretaceous deposits, and they occur in floodplain deposits of alluvial fan and meandering river settings. Thus, we conclude that dinosaurs inhabited volcanically influenced, alluvial fan, fluvial plain, and lake margins on the Korean Peninsula throughout the Cretaceous under a semi-arid climate with strong seasonality. The rarer occurrence of dinosaur tracks in older Cretaceous deposits in some basins might be attributed to the limited exposures of lake-margin deposits. It is inferred that the presence of large lakes as water sources, rich vegetation of gymnosperm trees as food, and semi-arid paleoclimatic conditions formed a general landscape and environmental setting favorable for dinosaurs and their preservation in the Cretaceous deposits of South Korea.

Keywords:

• Cretaceous
• Stratigraphy
• Geological ages
• Paleoenvironments
• Dinosaur
• Korea

ACKNOWLEDGMENTS

This work was supported by the National Research Foundation of Korea (NRF) grant (2010-0027501) funded by the Korea government (MEST). We thank Spencer Lucas and Justin Speilmann (New Mexico Museum of Natural History and Science) for their helpful reviews. Martin Lockley (University of Colorado Denver) also provided editorial help and suggestions for the title.