Psilopterus

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Psilopterus
Temporal range: Mid Oligocene-Late Pleistocene? [1] [2] (Deseadan-Lujanian)
~29.0–0.1  Ma
Psilopterus AMNH.jpg
Skull of P. lemoinei in American Museum of Natural History
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Cariamiformes
Family:† Phorusrhacidae
Subfamily:† Psilopterinae
Genus:† Psilopterus
Moreno & Mercerat, 1891 [3]
Species [1]
  • P. bachmanni(Moreno & Mercerat, 1891) [3] (type) [4]
  • P. lemoinei(Moreno & Mercerat, 1891) [3]
  • P. affinis(Ameghino, 1899) [5]
  • P. colzecusTonni & Tambussi, 1988 [6]
Synonyms
  • PelecyornisAmeghino, 1891 [1]
  • StaphylornisMercerat, 1897 [1]

Psilopterus (Greek for "bare wing") is an extinct genus of phorusrhacid ("terror bird") from the Middle Oligocene to possibly the 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 (2.3–2.6 ft) in height [4] and weighed about 5 kilograms (11 lb), while the largest members of the genus were only about 8 kilograms (18 lb). [7] The birds resemble the modern cariama (Cariama cristata), except with a heavier build and considerably smaller wings. [1] 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. [2]

Contents

Description and taxonomy

The most recent systematic revision of Phorusrhacidae placed Psilopterus within the subfamily Psilopterinae, along with the genera Procariama and Paleopsilopterus , and divided Psilopterus into four species. [1]

Psilopterus bachmanni

Psilopterus bachmanni (Moreno & Mercerat, 1891) [3] is the smallest species of phorusrhacid, rivaled only by P. affinis. The species (and genera) is defined by the upper portion of a fused ankle and leg bone (the lectotype MLP-168 is a tarsometatarsus). Other material assigned the species includes additional leg bones that are probably from the same bird, [4] and an almost complete skeleton (PUM-15.904) [8] The material is from several sites in the Santa Cruz Formation in the Santa Cruz Province of Argentina dating to the Middle Miocene (Santacrucian). The most important diagnostic characteristics are a low skull and upper jaw (or maxilla; similar to the mesembriornithine phorusrhacids) [1] and the extreme slant of the front edge of the hole just before the eye (rostal portion of the antorbital fenestra), though there are also differences in the rest of the skeleton. [8]

Synonyms: [9]

Brodkorb considered Psilopterus minutus Amerghino, 1981 a separate species, [10] but the incomplete foot bone (tarsometatarsus) is indistinguishable from P. bachmanni. [1]

Psilopterus lemoinei

Life restoration of P. lemoinei Psilopterus.jpg
Life restoration of P. lemoinei

Psilopterus lemoinei (Moreno & Mercerat, 1891) [3] is contemporaneous with P. bachmanni and likely filled a very similar ecological niche, though P. lemoinei is slightly larger, with an estimated weigh approaching 8 kilograms (18 lb). [7] 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. [8] 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). [8] 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. [1]

Synonyms: [9]

Psilopterus affinus

Psilopterus affinus (Ameghino, 1899) [5] 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). [5] Additional specimens might help clarify the taxonomy of the four apparently unrelated species. [1] P. affinus was originally assigned to the genus Phororhacos despite the difference in size, [5] and is distinguished from P. bachmanni by a groove on the leg bone. [1] Bertelli et al. kept this species in Phororhacos. [11] Brodkorb assigned the species to Andrewsornis in 1967, [10] but this is no longer considered accurate. [1]

Psilopterus colzecus

Cranial view of Psilopterus colzecus tarsometatarsus.png
Caudal view of Psilopterus colzecus tarsometatarsus.png
Distal view of Psilopterus colzecus tarsometatarsus.png
P. colzecus tarsometatarsus from the front, back, and below

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, and leg (holotype MLP-76-VI-12-2), the species is defined by a groove in the front of the thigh bone (trochlea). The elements were found in the Arroyo Chasicó Formation in Buenos Aires Province of Argentina and are dated to the Late Miocene (Chasicoan). [6]

Classification

When P. bachmanni was originally described in 1891, few other birds now known as Phorusrhacids were described, but when Moreno & Mercerat named the taxon, they assigned Psilopterus (then Patagornis) bachmanni to a group with Phorusrhacos, Mesembriornis, and Stereornis, though the latter is now seen as a synonym of Phorusrhacos, [12] [1] that they named Stereornithidae. [3] Since then, Psilopterus was considered the ancestor of larger Phorusrhacids like Mesembriornis and the modern Cariama. [13] In 1927, Psilopterus was placed in its own family and subfamily, Psilopterinae, [14] and later recognized as being in its own family sometimes grouped with other Phorusrhacids like Palaeopsilopterus and Procariama. [1] However, in the phylogenetic analysis by Degrange et al. (2015), Psilopterus was found as the only psilopterine, [15] though a 2024 study reclassified Procariama as a psilopterine. [16] The following phylogenetic tree shows the internal relationships of Phorusrhacidae under the exclusion of Brontornis as published by Degrange and colleagues in 2015, which recovers Psilopterus as the only member of Psilopterinae as a sister clade to Mesembriornithinae. [15]

Restoration of P. bachmanni Psilopterus bachmanniDB24.jpg
Restoration of P. bachmanni
Cariamiformes

Paleobiology

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. Like modern seriemas, psilopterines like Psilopterus would have fed on smaller animals based on their osteological traits. [17] It has been also suggested that, in contrast to the other larger terror birds, Psilopterus may have been able to fly, [6] probably in a brief and clumsy manner like that of extant seriemas, [18] with body mass estimates and hind limb proportions of psilopterines being similar to those of certain birds like Psophia and Otis which often walk but are able to run and fly. [19] It is likely that psilopterines would have more preferred to run than fly, and that they would have utilized flight to reach the treetops for nesting and protection against predators. [17]

Paleoenvironment

Psilopterus bachmanni & lemoinei lived during the middle Miocene in the Santa Cruz Formation, which preserves mostly a coastal environment, but also forested and grassland regions. [20] The area had little rainfall, so forests developed around lakes and rivers, giving Santa Cruz a diverse environment. During the Miocene, the climate was similar to those of the coasts of Chile with semi-temperate forests and oceanic winds. Grasslands began spreading into Argentina during the Miocene, though much of inner Patagonia was still arid with small rainforests in between. [21] [20] Large, herbivorous, South American notoungulate mammals like the toxodontids Nesodon and Adinotherium were the large low browsers, with rabbit-like interatheriiid Protypotherium being frugivorous. [21] Both mammalian and avian carnivores inhabited the area, the largest being the phorusrhacid Phorusrhacos. Marsupials also lived in the region, including the large carnivorous sparassodont Borhyaena. [20] Psilopterus lemoinei is also known from the coastal Monte Leon Formation that was in the same region in Santa Cruz, but part of the older lower Miocene age. [22] [23] Monte Leon preserved more mudstone and estuarine sediments, but with a very similar fauna to the Santa Cruz Formation as the two formations had a direct transition. [22]

Related Research Articles

<span class="mw-page-title-main">Phorusrhacidae</span> Extinct family of flightless birds

Phorusrhacids, colloquially known as terror birds, are an extinct family of large carnivorous, mostly flightless birds that were among the largest apex predators in South America during the Cenozoic era. Their definitive fossil records range from the Middle Eocene to the Late Pleistocene around 43 to 0.1 million years ago, though some specimens suggest that they were present since the Early Eocene.

<i>Phorusrhacos</i> Extinct genus of birds

Phorusrhacos is an extinct genus of giant flightless terror birds that inhabited South America during the Miocene epoch. Phorusrhacos was one of the dominant land predators in South America at the time it existed. It is thought to have lived in woodlands and grasslands.

<i>Titanis</i> Extinct genus of birds

Titanis is a genus of phorusrhacid, an extinct family of large, predatory birds, in the order Cariamiformes that inhabited the United States during the Pliocene and earliest Pleistocene. The first fossils were unearthed by amateur archaeologists Benjamin Waller and Robert Allen from the Santa Fe River in Florida and were named Titanis walleri by ornithologist Pierce Brodkorb in 1963, the species name honoring Waller. The holotype material is fragmentary, consisting of only an incomplete right tarsometatarsus and phalanx, but comes from one of the largest phorusrhacid individuals known. In the years following the description, many more isolated elements have been unearthed from sites from other areas of Florida, Texas, and California. The species was classified in the subfamily Phorusrhacinae, which includes some of the last and largest phorusrhacids like Devincenzia and Kelenken.

<i>Protypotherium</i> Extinct genus of notoungulates

Protypotherium is an extinct genus of notoungulate mammals native to South America during the Oligocene and Miocene epochs. A number of closely related animals date back further, to the Eocene. Fossils of Protypotherium have been found in the Deseadan Fray Bentos Formation of Uruguay, Muyu Huasi and Nazareno Formations of Bolivia, Cura-Mallín and Río Frías Formations of Chile, and Santa Cruz, Salicas, Ituzaingó, Aisol, Cerro Azul, Cerro Bandera, Cerro Boleadoras, Chichinales, Sarmiento and Collón Curá Formations of Argentina.

<i>Andalgalornis</i> Extinct genus of birds

Andalgalornis is a genus of flightless predatory birds of the extinct family Phorusrhacidae that lived in Argentina. The type and only species is A. steulleti.

<i>Brontornis</i> Extinct genus of birds

Brontornis is an extinct genus of giant bird that inhabited Argentina during the Early to Middle Miocene. Its taxonomic position is highly controversial, with authors alternatively considering it to be a cariamiform, typically a phorusrhacid or an anserimorph.

<i>Mesembriornis</i> Extinct genus of birds

Mesembriornis is a genus of intermediate-sized phorusrhacids that grew up to 1.5 metres (4.9 ft) in height. They represent a well-distinct lineage of terror birds, differing from the massive large groups and the smaller Psilopterinae. In general proportions, they most resembled the Patagornithinae which flourished somewhat earlier, mainly to the south of the range of Mesembriornis. Fossils of the terror bird have been found in Montehermosan deposits of the Monte Hermoso Formation, as well as the Andalgala Formation and Chapadmalal Formation in Argentina.

<i>Paraphysornis</i> Extinct genus of birds

Paraphysornis is an extinct genus of giant flightless terror birds that inhabited Brazil during Late Oligocene or Early Miocene epochs. Although not the tallest phorusrhacid, Paraphysornis measured up to 1.4 metres tall at the hips and weighed around 180–240 kilograms (400–530 lb). It was also a notably robust bird, having short and robust tarsal bones not suited for pursuit hunting.

<i>Kelenken</i> Extinct genus of birds

Kelenken is a genus of phorusrhacid, an extinct group of large, predatory birds, which lived in what is now Argentina in the middle Miocene about 15 million years ago. The only known specimen was discovered by high school student Guillermo Aguirre-Zabala in Comallo, in the region of Patagonia, and was made the holotype of the new genus and species Kelenken guillermoi in 2007. The genus name references a spirit in Tehuelche mythology, and the specific name honors the discoverer. The holotype consists of one of the most complete skulls known of a large phorusrhacid, as well as a tarsometatarsus lower leg bone and a phalanx toe bone. The discovery of Kelenken clarified the anatomy of large phorusrhacids, as these were previously much less well known. The closest living relatives of the phorusrhacids are the seriemas. Kelenken was found to belong in the subfamily Phorusrhacinae, along with for example Devincenzia.

Physornis is an extinct genus of giant flightless predatory birds of the family Phorusrhacidae or "terror birds", most closely related to Paraphysornis, that lived in Argentina. The type species is P. fortis. It lived during the Middle to Late Oligocene (Deseadan). Few fossils are known, but the available material suggests that Physornis was one of the largest phorusrhacids.

<i>Devincenzia</i> Extinct genus of birds

Devincenzia is an extinct genus of giant flightless predatory birds in the family Phorusrhacidae or "terror birds" that lived during the Early Miocene (Deseadan) Fray Bentos Formation of Uruguay, Late Miocene (Huayquerian) Ituzaingó Formation, Early Pliocene (Montehermosan) of Argentina, and possibly the Early Pleistocene Raigón Formation of Uruguay. The type species D. pozzi was formerly known as Onactornis pozzi. The largest possible specimen weighed up to 350 kilograms (770 lb), making it one of the largest phorusrhacids and carnivorous birds known.

<i>Patagornis</i> Extinct genus of birds

Patagornis is a genus of extinct flightless predatory birds of the family Phorusrhacidae. Known as "terror birds", these lived in what is now Argentina during the Early and Middle Miocene; the Santa Cruz Formation in Patagonia contains numerous specimens. Patagornis was an agile, medium sized Patagornithine and was likely a pursuit predator.

<i>Andrewsornis</i> Extinct genus of birds

Andrewsornis is an extinct genus of giant flightless predatory birds of the family Phorusrhacidae or "terror birds" that lived in Oligocene Argentina. Fossils have been found in the Sarmiento Formation, and possibly the Agua de la Piedra Formation.

<i>Procariama</i> Extinct genus of birds

Procariama is an extinct monotypic genus of phorusrhacid, which lived from the Late Miocene to the Late Pliocene of Argentina. Fossils of the animal have been found in six places, in the Cerro Azul and Andalhuala Formations. More specifically in the Andagalá department and in the north of the Belén department of the Catamarca province, with a single location in the La Pampa province. The type and only species, Procariama simplex, is the largest member of the subfamily Psilopterinae.

<i>Llallawavis</i> Extinct genus of birds

Llallawavis scagliai is a large, extinct predatory bird from Pliocene Argentina. Its fossil is the most complete fossil of a phorusrhacid yet found.

The Agua de la Piedra Formation is a Late Oligocene geologic formation of the Malargüe Group that crops out in the southernmost Precordillera and northernmost Neuquén Basin in southern Mendoza Province, Argentina.

Dryornis, also called the Argentinian vulture, is an extinct genus of cathartid, known from Argentina. The genus contains two species, D. pampeanus and D. hatcheri.

Patagorhacos is an extinct genus of medium-sized phorusrhacid from the early Miocene of Patagonia. Currently only the single species Patagorhacos terrificus is known, which is represented by two highly fragmentary specimen, one belonging to the back of the skull and the other being the distal end of a leg bone. It was described together with the contemporary rheid Opisthodactylus horacioperezi.

<span class="mw-page-title-main">Santa Cruz Formation</span> Geological formation in Patagonia

The Santa Cruz Formation is a geological formation in the Magallanes/Austral Basin in southern Patagonia in Argentina and adjacent areas of Chile. It dates to the late Early Miocene epoch, and is contemporaneous with the eponymous Santacrucian age of the SALMA timescale. The Santa Cruz Formation is known for its abundance of vertebrate fossils, including South American native ungulates, as well as rodents, xenarthrans, and metatherians.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Alvarenga, Herculano M. F.; Höfling, Elizabeth (2003). "Systematic Revision of the Phorusrhacidae (Aves: Ralliformes)". Papéis Avulsos de Zoologia. 43 (4): 55–91. doi: 10.1590/S0031-10492003000400001 . ISSN   0031-1049.
  2. 1 2 Jones, W.; Rinderknecht, A.; Alvarenga, H.; Montenegro, F.; Ubilla, M. (2017). "The last terror birds (Aves, Phorusrhacidae): new evidence from the late Pleistocene of Uruguay". Paläontologische Zeitschrift . 92 (2): 365–372. doi:10.1007/s12542-017-0388-y. S2CID   134344096. Note: their date of 96 thousand years BP is the maximum age, obtained from the bottom of the fossil-containing stratum.
  3. 1 2 3 4 5 6 Moreno, Francisco P.; Mercerat, Alcides (1891). "Catálogo de los pájaros fósiles de la República Argentina conservados en el Museo de La Plata". Anales del Museo de la Plata (in Spanish). 1: 7–71.
  4. 1 2 3 Richmond, Charles W. (1902). "List of generic terms proposed for birds during the years 1890 to 1900, inclusive, to which are added names omitted by Waterhouse in his 'Index generum avium'". Proceedings of the United States National Museum. 24 (1267): 663–730. doi:10.5479/si.00963801.1267.663. hdl: 2027/coo.31924090189725 .
  5. 1 2 3 4 Ameghino, Florentino (1899). "Sinopsis geológico-paleontológica, Suplemento (Adiciones y correciones)". La Plata (in Spanish): 13 pp.
  6. 1 2 3 Tonni, Eduardo P.; Tambussi, Claudia (1988). "Un nuevo Psilopterinae (Aves: Ralliformes) del Mioceno tardio de la Provincia de Buenos Aires, Republica Argentina". Ameghiniana (in Spanish). 25: 155–160.
  7. 1 2 DEGRANGE, FEDERICO J.; TAMBUSSI, CLAUDIA P. (2011). "Re-Examination of Psilopterus Lemoinei (Aves, Phorusrhacidae), A Late Early Miocene Little Terror Bird from Patagonia (Argentina)". Journal of Vertebrate Paleontology. 31 (5): 1080–1092. Bibcode:2011JVPal..31.1080D. doi:10.1080/02724634.2011.595466. ISSN   0272-4634. JSTOR   41407663. S2CID   86790415.
  8. 1 2 3 4 Sinclair, W.; Farr, M. (1932). "Aves of the Santa Cruz beds". Reports of the Princeton University Expeditions to Patagonia (1896–1899). 7: 157–191.
  9. 1 2 Per Alvarenga & Höfling (2003), who rely on Brodkorb (1967).
  10. 1 2 Brodkorb, Pierce (1967). "Catalogue of fossil birds, Part III (Ralliformes, Ichthyornithiformes, Charadriiformes)". Bulletin of Florida State Museum. 2: 99–220.
  11. ↑ Taxonomic opinions tied to S. Bertelli et al. 2007 at Fossilworks.org
  12. ↑ Brodkorb, P. (1967). Catalogue of fossil birds: part 3 (Ralliformes, Ichthyornithiformes, Charadriiformes). University of Florida.
  13. ↑ Rovereto, C. (1914). Los estratos araucanos y sus fósiles. An. del Mus. Nac. Hist. Nat. Buenos Aires, 25.
  14. ↑ Dolgopol de Saez, M. (1927). Las aves corredoras fósiles del Santacrucense. In Anales de la Sociedad Científica Argentina (Vol. 103, pp. 145-64).
  15. 1 2 Degrange, Federico J.; Tambussi, Claudia P.; Taglioretti, Matías L.; Dondas, Alejandro; Scaglia, Fernando (2015-03-04). "A new Mesembriornithinae (Aves, Phorusrhacidae) provides new insights into the phylogeny and sensory capabilities of terror birds". Journal of Vertebrate Paleontology. 35 (2): e912656. Bibcode:2015JVPal..35E2656D. doi:10.1080/02724634.2014.912656. hdl: 11336/38650 . ISSN   0272-4634. S2CID   85212917.
  16. ↑ LaBarge, T. W.; Gardner, J. D.; Organ, C. L. (2024). "The evolution and ecology of gigantism in terror birds (Aves, Phorusrhacidae)". Proceedings of the Royal Society B: Biological Sciences. 291 (2021). 20240235. doi:10.1098/rspb.2024.0235. PMC  11040249. PMID   38654650. Supplementary Information
  17. 1 2 Acosta Hospitaleche, C.; Jones, W. (2024). "Insights on the oldest terror bird (Aves, Phorusrhacidae) from the Eocene of Argentina". Historical Biology: An International Journal of Paleobiology: 1–9. doi:10.1080/08912963.2024.2304592. S2CID   267475903.
  18. ↑ Degrange, F.J.; Noriega, J.I.; Areta, J.I. (2012). "9. Diversity and paleobiology of the santacrucian birds". In Vizcaíno, S.F.; Kay, R.F.; Bargo, M.S. (eds.). Early Miocene Paleobiology in Patagonia: high-latitude paleocommunities of the Santa Cruz Formation. Cambridge: Cambridge University Press. pp. 138–155. doi:10.1017/CBO9780511667381.010. ISBN   978-0521194617.
  19. ↑ Degrange, F.J. (2015). "Hind limb morphometry of terror birds (Aves, Cariamiformes, Phorusrhacidae): functional implications for substrate preferences and locomotor lifestyle". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 106 (4): 257–276. Bibcode:2015EESTR.106..257D. doi:10.1017/S1755691016000256. hdl: 11336/44728 .
  20. 1 2 3 Croft, D. A.; Simeonovski, V. (2016). Horned armadillos and rafting monkeys: the fascinating fossil mammals of South America . Life of the past. Bloomington (Ind.): Indiana University Press. pp.  119-121. ISBN   978-0-253-02084-0.
  21. 1 2 Townsend, K. E. B.; Croft, D. A. (2008). "Diets of notoungulates from the Santa Cruz Formation, Argentina: new evidence from enamel microwear". Journal of Vertebrate Paleontology. 28 (1): 217–230. doi:10.1671/0272-4634(2008)28[217:DONFTS]2.0.CO;2. ISSN   0272-4634. JSTOR   30126346.
  22. 1 2 Cuitiño, J. I.; Fernicola, J. C.; Raigemborn, M. S.; Krapovickas, V. (2019). "Stratigraphy and depositional environments of the Santa Cruz Formation (early–middle Miocene) along the Río Santa Cruz, southern Patagonia, Argentina". Publicación Electrónica de la Asociación Paleontológica Argentina. 19 (2): 14–33. doi: 10.5710/PEAPA.27.07.2019.294 . hdl: 11336/110039 .
  23. ↑ Kay, Richard F.; Vizcaíno, Sergio F.; Bargo, M. Susana; Spradley, Jackson P.; Cuitiño, José I. (2021-08-01). "Paleoenvironments and paleoecology of the Santa Cruz Formation (early-middle Miocene) along the Río Santa Cruz, Patagonia (Argentina)". Journal of South American Earth Sciences. 109: 103296. Bibcode:2021JSAES.10903296K. doi: 10.1016/j.jsames.2021.103296 . ISSN   0895-9811. S2CID   233693434.
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