Genus: Hyphalosaurus GAO, TANG & WANG, 1999
Etymology: Greek, hyphalos, “submerged, underwater”, and Greek, sauros, “lizard”; Underwater lizard.
= Sinohydrosaurus LI, ZHANG & LI, 1999
Etymology:

Species: lingyuanensis GAO, TANG & WANG, 1999
Etymology: In reference to Lingyuan

Referred material:

BUFFETAUT, LI, TONG, & ZHANG, 2007

Locality: Wanfuotang, Yixian, Liaoning Province, China.

Horizon: Yixian Formation.

Biostratigraphy:

Age: Early Cretaceous.

Material:

SPM R10: Embryo.

Note: Mutation with two necks and heads.

SPM R13: Embryo.