page_title: Psilopterus
section_title: P. lemoinei
hierarchical_section_title: Psilopterus / Description and taxonomy / P. lemoinei
caption_attribution_description: English: Life reconstruction of the terror bird Psilopterus lemoinei. Nederlands: Artist's impression van de schrikvogel Psilopterus lemoinei.
context_page_description: Psilopterus is an extinct genus of phorusrhacid from the Middle Oligocene to Late Pleistocene of Argentina and Uruguay. Compared to other phorusrhacids, members of the genus are both relatively gracile and diminutive, and include the smallest known species of terror bird: with the head raised P. bachmanni was 70–80 centimeters in height and weighed about 5 kilograms, while the largest members of the genus were only about 7 kilograms. The birds resemble the modern cariama, except with a heavier build and considerably smaller wings. The strong morphological similarity between the claws of the predatory cariama and Psilopterus, both of which are sharp, curved, and laterally compressed, may indicate they were used to strike prey. In contrast to the other, larger terror birds, Tonni and Tambussi also suggested Psilopterus could use their claws to climb trees, and could even fly, but this has been rejected in more recent literature. Fossil finds in Uruguay indicate the genus may have survived until 96,040 ± 6,300 years ago, millions of years after the larger phorusrhacids became extinct.
context_section_description: Psilopterus lemoinei (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 7 kilograms (15 lb). 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)
caption: Restoration of P. lemoinei
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