Genus: Macrocephalosaurus TUPI-CALDAS, 1933 non GILMORE, 1943
Etymology: Latin, macro, "big, long," Greek, kephale, "head" and Greek, sauros, "lizard."

Species: mariensis TUPI-CALDAS, 1933
Etymology:
= Hyperodapedon mariensis (TUPI-CALDAS, 1933)

Holotype: MCN 1867

Locality: Near the town of Santa Maria, Rio Grande Do Sul State State, Brazil.

Horizon: Upper Santa Maria Member, Santa Maria Formation.

Biostratigraphy:

Age: Ladinian Stage, Upper Mid Triassic Epoch, Middle Triassic.

Material: Skull and nearly complete skeleton.

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