(Moreno & Mercerat, 1891) is contemporaneous with P. bachmanni and likely filled a very similar ecological niche, though P. lemoinei is slightly larger, with an estimated weigh approaching . The species is defined by part of a lower leg bone (the lectotype, MLP-162, is the distal end of a tibiotarsus), but a wide variety of material has been referred to the taxon. This material has been found at a number of sites in the Monte León and Santa Cruz Formations in the Santa Cruz Province of Argentina that are dated to the Middle Miocene (Santacrucian). Diagnostic characteristics include a higher skull and upper jaw (maxilla), and the front portion of the hole in front of the eyes (rostral edge of the antorbital fenestra) is less slanted. Additional differences in the remainder of the skeleton are noted in Sinclair and Farr (1932). A number of discrepancies between various specimens have been attributed to differences in age or sex, but material currently assigned to P. lemonei and P. bachmanni may be reclassified at the species level if reexamined in depth. Synonyms: Patagornis lemoinei Moreno & Mercerat, 1891 Psilopterus australis Moreno & Mercerat, 1891 Pelecyornis tubulatus Ameghino, 1895 (synonym of Psilopterus australis) Phororhacos modicus Ameghino, 1895 Staphylornis gallardoi Mercerat, 1897 (possible synonym of Psilopterus australis) Staphylornis erythacus Mercerat, 1897 (possible synonym of Psilopterus australis) Pelecyornis tenuirostris Sinclair & Farr, 1932 (synonym of Psilopterus australis) Psilopterus affinus Psilopterus affinus (Ameghino, 1899) is the most poorly known species of terror bird, represented only by part of a leg bone (tarsometatarsus, MACN-A-52-184) which indicates the bird was very close to P. bachmanni in size. P. affinus is one of several species known from fragmentary material found in 1899 in the Chubut Province of Argentina (Patagonia), in rocks which dated to the Middle to Late Oligocene (Deseadan). Additional specimens might help clarify the taxonomy of the four apparently unrelated species. P. affinus was originally assigned to the genus Phororhacos despite the difference in size, and is distinguished from P. bachmanni by a groove on the leg bone. Bertelli et al. kept this species in Phororhacos. Brodkorb assigned the species to Andrewsornis in 1967, but this is no longer considered accurate. Psilopterus colzecus The most recently discovered species in the genus, Psilopterus colzecus Tonni & Tambussi, 1988, is similar to P. lemoinei in size. Known only from a single incomplete skeleton that includes parts of the jaw, arm,