Genus: Hyphalosaurus GAO, TANG & WANG, 1999
Etymology: Greek, hyphalos, “submerged, underwater”, and Greek, sauros, “lizard”; Underwater lizard.
Species: baitaigouensis JI, JI, CHENG, YOU, LÜ & YUAN, 2004
Locality: Baitaigou village, northwest of the Yizhou town, Yixian County, Liaoning Province, China.
Horizon: Yixian Formation, Jehol Group.
Biostratigraphy: Psittacosaurus Fauna, Confuciusornis Avifauna.
Age: Valanginian Stage, Upper Neocomian Subepoch, Early Early Cretaceous Epoch, Early Cretaceous.
HOU, LI, KSEPK, GAO, & NORELL, 2009
LPM-R168: Flex shelled egg and hatchling.
LPM-R169: Flex shelled egg.
JI, JI, LU, YOU & YUAN, 2006
CAGS-IG-03-7-02: Fragmentary adult with 12 leathery eggs and embryos.