Lockeia gigantus ichnosp. nov. in the Lacustrine Deposits of the Early Cretaceous Jinju Formation, Southern Coast of Korea

About 450 specimens of Lockeia were discovered from the lacustrine siltstone of the Early Cretaceous Jinju Formation of Jin Island, southern coast of Korea. They are very elongated, seed-shaped Lockeia characterized by a large size, mostly 60-70 mm long and 15-20 mm wide. They are characteristically sharp longitudinal furrow bounded by steeply inclined both margins, elevated marginal rims and sharp pointed both longitudinal furrow ends. This trace fossil is herein described as Lockeia gigantus ichnosp. nov. Plicatounio, a freshwater bivalve which does not occur occurs occasionally within Lockeia gigantus is regarded as the most-likely producer of this resting trace fossil. This new trace fossil represents the largest Lockeia ever known and the first record of Lockeia from the Cretaceous non-marine
deposits in the world. This fossil also represents an unusual example of resting trace fossil (Lockeia) associated with a possible producer (bivalve Plicatounio) lived in community in the shallow lacustrine environment.