Genus: Eomadtsoia GOMEZ, GARBEROGLIO & ROUGIER, 2019
Etymology: Greek, eos, "dawn" for the early divergence of a large madtsoiid at the base of a clade of gigantic forms, + Madtsoia Simpson, 1933, type genus of Madtsoiidae.

Species: ragei GOMEZ, GARBEROGLIO & ROUGIER, 2019
Etymology: In honor of Jean-Claude Rage for his outstanding work on fossil snakes.

Holotype: MPEF-PV 2378

Locality: El Uruguayo fossil site, southeastern slopes of the Somun Cura Massif, Chubut Province, Patagonia, Argentina.

Horizon: Second facies association, La Colonia Formation.

Biostratigraphy:

Age: Maastrichtian Stage, Uppermost Senonian Subepoch, Uppermost Gulf Epoch, Late Cretaceous-Danian Stage, early Paleocene Epoch, Early Paleogene Peroid, Early Tertiary Sub-era, Early Cenozoic Era.

Material: Isolated middle precloacal vertebra.

Referred material:

Locality: El Uruguayo fossil site or a nearby loaclity north of El Buitre Hill, southeastern slopes of the Somun Cura Massif, Chubut Province, Patagonia, Argentina.

Horizon: Second facies association, La Colonia Formation.

Biostratigraphy:

Age: Maastrichtian Stage, Uppermost Senonian Subepoch, Uppermost Gulf Epoch, Late Cretaceous-Danian Stage, early Paleocene Epoch, Early Paleogene Peroid, Early Tertiary Sub-era, Early Cenozoic Era.

Material:

MPEF-PV 641, 2379-2387: Several isolated precloacal vertebrae.

Tentatively referred specimens:

MPEF-PV 644-649, 2388-2389: Fragmentary precloacal vertebrae and fragments of vertebrae.