Genus: Mei XU & NORELL, 2004
Etymology: Chinese, mei, "to sleep soundly."

Species: long XU & NORELL, 2004
Etymology: Chinese, long, "dragon"; Sleeping dragon.

Holotype: IVPP V12733

Locality: Lujiatun, Shangyuan, Beipiao City, western Liaoning Province, China.

Horizon: Horizon 1, Lower part of the Yixian Formation, Jehol Group.

Biostratigraphy: Psittacosaurus Fauna, Confuciusornis Avifauna.

Age: Valanginian Stage, Upper Neocomian Subepoch, Early Early Cretaceous Epoch, Early Cretaceous.

Material: Nearly complete specimen.
Note: Has a furcula.

Note: Has its head burried below an arm, and body curled up, similar to modern birds sleeping.

Referred material:

GAO, MORSCHHAUSER, VARRICCHIO, LIU, & BO, 2012

DNHM D2154: A nearly complete, articulated skeleton including skull, complete cervical series, partial dorsal series, complete sacrum and ilium, a partial pubis, complete hind limbs, fairly complete caudal series adn complete forelimbs, exceptu fro teh furculua and much of the manus. the missing forelimb elements may still be present in the matrix, but are not currently exposed.

Note: Gao, et al., suggest Mei long died in a burrow.