Crypturellus reai was named by Chandler (2012) [The holotype humerus (AMNH: FAM 9151), Crypturellus, Tinamus, and Rhynchotus have the distal border of the head of the humerus extending distad, medially occluding the capital incision; Nothocercus, Nothura, Eudromia, Nothoprocta, and Tinamotis have a distinctly rounded distal border with a medially open incision. The holotype, Crypturellus, and Tinamotis share the attachment for the M. infraspinatus oriented ventrally, not caudally as in Tinamus, Rhynchotus, and the other tinamid genera examined. Within Crypturellus, C. reai differs from all other species examined in having the head of the humerus more deeply undercut medially. Crypturellus reai also differs from all other species of Crypturellus examined in that the fossa of the M. brachialis is nearly straight and extends diagonally across the shaft. Crypturellus reai has the attachment for the ventral collateral ligament (ventral supracondylar tubercle) slanted more caudally, and not located in the plane of the long axis of the humerus as in all the examined species of Crypturellus and other tinamid genera.]. Its type specimen is AMNH:FAM 9151, a limb element (left humerus), and it is a 3D body fossil. Its type locality is Wash of Cañadón de Las Vacas, which is in a Santacrucian terrestrial horizon in the Santa Cruz Formation of Argentina.