Genus: Mollesaurus FERNANDEZ, 1999
Etymology : From the Los Molles Formation of the Neuquen Basin, Argentina, and Greek, sauros, “lizard.”

Species: periallus FERNANDEZ, 1999
Etymology: Greek, periallos, “before all others.”

Holotype: Museo Olsacher, Direccion Provincal de Mineria, Zapala, Neuquen, MOZ 2282 V

Locality: Chacaio Sur, 30°15'S, 70°18'W, 70 km southwest of Zapala, Department of Zapala, Neuquen Province, Northwestern Patagonia, Argentina.

Horizon: Los Molles Formation.

Biostratigraphy: Emilea giebeli zone, subzone of Emilea formis.

Age: Early Bajocian Stage, Lower Dogger Epoch, Middle Jurassic.

Material: Posterior half of the skull and part of the vertebral column comprised of 39 articulated vertebrae and ribs.