Genus: Achillesaurus MARTINELLI & VERA, 2007
Etymology: Latin, Achilles, in reference to Achilles' heal, the week point of the Achilles in the book "Iliad" written by Homer, because the holotype has diagnostic features in this portion of the skeleton, and Greek, sauros, "lizard."

Species: manazzonei MARTINELLI & VERA, 2007
Etymology: In honor of Prof. Rafael Manazzone, an amateur paleontologist who provided valuable data about Patagonian fossil localities, and assited to several paleontological field trips.

Holotype: MACN-PV-RN 1116

Locality: Paso Cordova Locality, Rio Negro Province, Argentina.

Horizon: Bajo de la Carpa Formation, Rio Colorado Subgroup, Neuquen Group.

Biostratigraphy:

Age: Santonian Stage, Lower Senonian Subepoch, Lower Gulf Epoch, Late Cretaceous.

Material: Last sacral vertebra and the following 2 procoelous caudals with an articulated chevron, a partial proximal bioncave caudal (possibly the fourth), a portion of a distal caudal centrum, fragmentary left ilium, proximal end of the left femur, distal end of the left tibia articulated with the astragalus, proximal portion of the left metatarsals II, III, and IV, and cast of the ilium and the vertebrae as originally found prior to disarticulation.