Genus: Tathiodon SIMPSON, 1927
Etymology: Greek, tatheis, “stretched, extended” and Greek, odon, “tooth”: Extended tooth.

Species: agilis SIMPSON, 1927
Etymology: Latin, agilis, "agile, nimble, quick."

Holotype: YPM 13649

Locality: Reeds YPM Quarry 9, (Mammal Quarry), T22N, R77W, Sec. 12, Como Bluff, Albany County, Wyoming.

Horizon: Brushy Basin Member, Morrison Formation.

Biostratigraphy: Zone 3.

Age: Upper Part, Comobluffian age, Kimmeridgian Stage, uppermost Malm Epoch, Late Jurassic.

Material: Left lower jaw with 2 molars.