Species: macrothorax ROLANDO, MOTTA, AGNOLIN, MANABE, TSUIHIJI & NOVAS, 2022
Etymology: Latin, macro, "big" and Latin, thorax, refering to its wide thoracic cavity (which has, approxmately, more thatn 1.2- m width).
Holotype: MPM 21,545
Locality: Megaraptorid site (Locality 3 of Novase et al), La Anita Farm, 30 km SW of El Calafate city, Santa Cruz Province, Argentina.
Horizon: Chorrillo Formation.
Biostratigraphy:
Age: Maastricthian Stage, Senonian Subepoch, Gulf Epoch, Late Cretaceous.
Material: Axis, dorsals, 2, 3, 4, 5, 6, 7, 9, 10 (or 11), and 12 (or 13), 2 porximal caudals (caudal A, probably pertaing to caudal 3-5 and caudal B, pertainig to caudal 6-8), some fragmentary vertebrae, 3 incomplete cervical ribs, numerous incomplete or fragmentary dorsal ribs, numerous gastral elements, left coracoid, distal end of a secont metatarsal, and fragments of the scapula.