The Sinuiju Formation(신의주층) is a geologic formation in North Korea. Formerly of uncertain age, it is now thought to be Early Cretaceous. A variety of fossils are known from the formation, including those of anurognathidpterosaurs (possibly Jeholopterus) and birds such as the specimen of a very large enantiornithine with a 5 cm (2.0 in) long tibia and a 3.5 cm (1.4 in) long pygostyle. Frogs have also been found in the formation.[1][2] Numerous compression fossils of insects have also been found.[3]
^So, K. S.; Kim, P. H.; Won, C. G. (2024). "First Articulated Rhamphorhynchoid Pterosaur from the Early Cretaceous of the Democratic People's Republic of Korea". Paleontological Journal. 57 (1 supplement): S90 –S94. doi:10.1134/S003103012360018X.
Won, C.G.; So, K.S.; Kim, H.C. (2022), "A new odonatan (Stenophlebiidae) from the Lower Cretaceous Sinuiju Formation of North Phyongan Province, the Democratic People's Republic of Korea", Palaeoworld, 31: 116–120, doi:10.1016/j.palwor.2021.02.002