They ranged in height from 1 to 3m (3 to 10ft). One of the largest specimens from the Early Pleistocene of Uruguay, possibly belonging to Devincenzia, would have weighed up to 350 kilograms (770lb).[5][6] Their closest modern-day relatives are believed to be the 80-centimetre-tall (31in)seriemas. Titanis walleri, one of the larger species, is known from Texas and Florida in North America. This makes the phorusrhacids the only known large South American predator to migrate north in the Great American Interchange that followed the formation of the Isthmus of Panamaland bridge (the main pulse of the interchange began about 2.6 Ma ago; Titanis at 5 Ma was an early northward migrant).[7]
It was once believed that T. walleri became extinct in North America around the time of the arrival of humans,[8] but subsequent datings of Titanis fossils provided no evidence for their survival after 1.8 Ma.[9] However, reports from Uruguay of new findings of phorusrachids such as a specimen of Psilopterus dating to 96,040 ± 6,300 years ago would imply that phorusrhacids survived in South America until the late Pleistocene.[lower-alpha 2]
Phorusrhacids may have even made their way into Africa and Europe, if the genus Lavocatavis from Algeria and Eleutherornis from France and Switzerland are included.[10][11] However, the taxonomic placement of both taxa within phorusrhacids are considered highly questionable, and their remains are too fragmentary to be included in phylogenetic analyses.[12][13][14] Possible specimens have also been discovered from the La Meseta Formation of Seymour Island, Antarctica, suggesting that this group had a wider geographical range in the Paleogene.[15]
The closely related bathornithids occupied a similar ecological niche in North America across the Eocene to Early Miocene; some, like Paracrax, were similar in size to the largest phorusrhacids.[16][17] At least one analysis recovers Bathornis as sister taxa to phorusrhacids, on the basis of shared features in the jaws and coracoid,[18] though this has been seriously contested, as these might have evolved independently for the same carnivorous, flightless lifestyle.[19]
Description
Phorusrhacinae skulls compared
The neck can be divided into three main regions. In the higher regions of the neck, the phorusrhacid has bifurcate neural spines (BNS), while it has high neural spines in its lower regions. This suggests that the phorusrhacid had a highly flexible and developed neck allowing it to carry its heavy head and strike with terrifying speed and power. Although the phorusrhacid externally looks like it has a short neck, its flexible skeletal neck structure proves that it could expand farther beyond the expected reach and intimidate its prey using its height, allowing it to strike more easily. Once stretched out into its full length in preparation for a downward strike, its developed neck muscles and heavy head could produce enough momentum and power to cause fatal damage to the terror bird's prey.[20]
Kelenken guillermoi, from the Langhian stage of the Miocene epoch, some 15 million years ago, discovered in the Collón Curá Formation in Patagonia in 2006, represents the largest bird skull yet found. The fossil has been described as being a 71-centimetre (28in), nearly intact skull. The beak is roughly 46cm (18in) long and curves in a hook shape that resembles an eagle's beak. Most species described as phorusrhacid birds were smaller, 60–90cm (2.0–3.0ft) tall, but the new fossil belongs to a bird that probably stood about 3m (9.8ft) tall. Scientists theorize that the large terror birds were extremely nimble and quick runners, able to reach speeds of 48km/h (30mph).[21] Examination of phorusrhacid habitats also indicates that phorusrhacids may have presented intense competition to predatory metatherian sparassodonts such as borhyaenids and thylacosmilids, causing the mammalian predators to choose forested habitats to avoid the more successful and aggressive avian predators on the open plains.[22]
The feet of the phorusrhacids had four toes, the first of which, known as the hallux, was reduced and did not touch the ground, while the others, corresponding to the second, third and fourth toes, were kept on the ground. Analysis of the resistance of the toes based on biomechanical models of curved beams, in particular of the second toe and its nail claw, indicate that it was modified into a "sickle claw" and was relatively uniform in various species and said claw would be relatively curved and large, which implies the need to keep it elevated to avoid wear or breakage due to contact with the ground, which would be achieved with a well-developed extensor tubercle and soft tissue pads on the fingers. The second toe, which was shorter and had fewer phalanges, also had more resistance and would make it easier to hold the claw off the ground and retain prey, a compromise with its predatory function and movement on the run, as occurs with modern seriemas, although to a lesser degree of specialization than dromaeosaurid dinosaurs.[23] This is further supported by footprints from the Late Miocene of the Río Negro Formation, showcasing a trackway made by a mid-to-large sized terror bird with functionally didactyl footprints, the inner toe with the sickle claw raised mostly off the ground akin to their Mesozoic counterparts.[24]
In the past, these birds were thought to have high beaks, round orbits, and vaulted braincases[25] though there was never enough empirical evidence to support this. However, new fossils have been discovered in Comallo, Argentina. These skulls reveal that the terror bird has a triangular dorsal view, a rostrum that is hooked and more than half the length of the actual skull, and a more compact caudal portion. The external nares and antorbital fenestras (areas found in the nose) were found to be more square than triangular. These all contribute to a skull that is more rectangular in view rather than triangular.[25] The structure of the fossils also suggest that these birds may have been swifter than originally thought.[25]
A skull from a smaller subspecies of this bird was also found recently. With this fossil, it was found that the internal structure of the beak is hollow and reinforced with thin-walled trabeculae. There is also an absence of both zona flexoria palatina and zona flexoria arcus jugalis, which are key features that relate to the evolution of cranial akinesis. The discovery of this skull allows for the establishment of primary osteological homologies, which are useful in comparative anatomy, functional morphology, and phylogenetic studies.[26]
Most phorusrhacids were very fast runners. All members possessed a large, sharp beak, a powerful neck and sharp talons. However, even with these attributes, the phorusrhacids are often assumed to have preyed on relatively small animals (about the size of a rabbit) that could be dispatched with a minimum of struggle. This is because with the phorusrhacids' beak proportions, the jaw could not generate a great deal of bite force with which to kill the prey. This is disputable as many big-game hunting predators such as Smilodon, great white sharks and Allosaurus have weaker bite forces and often laterally weak skulls as adaptations towards, not away from, killing large prey, relying instead on the presence of a cutting edge, a wide gape made possible by the reduction of jaw musculature, and the driving force of the body or neck.[27][28] Since phorusrhacids share many of the same adaptations, such as a large, laterally flattened skull with a sharp-edged beak and powerful neck musculature, it is possible that they were specialized predators of relatively large prey.
The bones of the beak were tightly fused together, making the beak more resilient to force from the front to back direction, thus suggesting that it could cause a great amount of harm through pecking as opposed to side-to-side head movements like shaking prey. Generally speaking, it is thought that a terror bird would use its feet to injure prey by kicking it, and to hold the prey down and dispatch by pecking at it with its large beak. Larger prey may also have been attacked by pecking and kicking,[29] or by using the beak as a blade to strike at or slash vital organs.
It has been recently shown that at least some phorusrhacids like Andalgalornis, while very fast runners in a straight line, were poor at tight turns at speed, which contradicts the idea of phorusrhacids being agile predators of small prey.[30]
Diet
All phorusrhacids are thought to have been carnivorous. The strong downwards curve from the tip of this beak suggests that it ripped the flesh from the body of other animals; many extant bird species with this feature are carnivorous. CT scans performed on the skull of a phorusrhacid reveal that the species would not have been able to shake its prey side to side, but rather exert significant downward force.[31]Florentino Ameghino claimed in a letter to Édouard Trouessart that he had specimens from Argentina of "petrified masses preserving skeletons of large rodents, Interatheriidae [small notoungulates] and even Proterotheriidae [deer-sized litopterns], with all their bones crushed and corroded, piled on with no apparent order and forming a nearly spherical mass with the skull in the center" that resembled giant owl pellets, suggesting that phorusrhacids may have swallowed their prey whole and regurgitated the indigestible parts similar to owls.[32][33] However, Ameghino never formally described these specimens and they have not yet been relocated, making it difficult to determine if they are phorusrhacid pellets.[33] Fossilized pellets from northwestern Argentina have also been suggested to pertain to small phorusrhacids like Procariama.[34]
Classification
The etymology of the name Phorusrhacidae is based on the type genus Phorusrhacos. When first described by Florentino Ameghino in 1887, the etymology of Phorusrhacos was not given. Current thinking is that the name is derived from a combination of the Greek words "phoros", which means bearer or bearing, and "rhakos", which translates to wrinkles, scars or rents.[35] Researchers have compared Phorusrhacidae with the living families of Cariamidae and Sagittariidae, but their differences in body mass are too drastic and, thus, one cannot overly depend on these living families for answers.
During the early Cenozoic, after the extinction of the non-bird dinosaurs, mammals underwent an evolutionary diversification, and some bird groups around the world developed a tendency towards gigantism; this included the Gastornithidae, the Dromornithidae, the Palaeognathae, and the Phorusrhacidae.[36] Phorusrhacids are an extinct group within Cariamiformes, the only living members of which are the two species of seriemas in the family Cariamidae. While they are the most taxon-rich group within Cariamiformes, the interrelationships between phorusrhacids are unclear due to the incompleteness of their remains.[37] A lineage of related predatory birds, the bathornithids, occupied North America prior to the arrival of phorusrhacids, living from the Eocene to Miocene and filled a similar niche to phorusrhacids.[38] Only one genus belongs in the family, Bathornis, according to a 2016 analysis by paleontologist Gerald Mayr, who noted that Bathornis was more lightly built, with longer limbs proportionally and skulls more akin to those of Cariama.[39]
Phylogenetic analysis of Cariamiformes and their relatives according to Mayr (2016) in his redescription of Bathornis:[39] A 2024 study finds Bathornis as closer to seriemas than phorusrhacids were.[14]
Following the revision by Alvarenga and Höfling (2003), there are now 5 subfamilies, containing 14 genera and 18 species:[40] These species were the product of adaptive radiation.[41] The following classification is based on LaBarge, Garderner & Organ (2024), and taxa identified as incertae sedis were all excluded from phylogenetic analysis in their study (except for Brontornis):[14]
Subfamily Phorusrhacinae — giant species 8.3 feet (2.5m) high (Kelenken up to 9.8 feet (3.0m) high[44]), but somewhat slender and decidedly more nimble than the Brontornithinae
Alvarenga and Höfling did not include the Ameghinornithidae from Europe in the phorusrhacoids; these have meanwhile turned out to be more basal members of Cariamae.[48] Though traditionally considered as members of the Gruiformes, based on both morphological and genetic studies (the latter being based on the seriema[49]) Cariamiformes may belong to a separate group of birds, Australaves, and their closest living relatives, according to nuclear sequence studies, are a clade consisting of Falconidae, Psittaciformes and Passeriformes.[50][51]
The following cladogram follows the analysis of Degrange and colleagues, 2015:[47]
During the Miocene and early Pliocene epochs, there was an increase in the phorusrhacid population size in South America, suggesting that, in that time frame, the various species flourished as predators in the savanna environment.
With the emergence of the Isthmus of Panama 2.7 million years ago, carnivorous dogs, bears, and cats from North America were able to cross into South America, increasing competition.[52] (They had been preceded by procyonids as early as 7.3 million years ago.[7]) The population of phorusrhacids declined thereafter according to older hypotheses, suggesting that competition with newly arrived predators was a major contributor to their extinction.[53] Similar ideas have been considered for sparassodonts and for South America's terrestrial sebecid crocodilians.[54]
However, the role of competitive displacement in South American predator lineages has been questioned by some researchers.[55] The timing of turnover events and the decline of South American predators do not correlate well with the arrival of large carnivores like canids or sabretooths (although they do correlate well with the earlier-arriving procyonids, which evolved to large body size in South America, but these were omnivorous[56]), with native South American predator lineages (including most phorusrhacids and all sparassodonts and sebecids) dying out well before the arrival of most larger placental carnivores.[57]Bathornithids, which were similar in ecology and are likely close relatives of phorusrhacids, existed entirely within North America during part of the Cenozoic and competed successfully for a time with large carnivorans such as nimravids,[17] before becoming extinct in the Early Miocene, about 20 million years ago. The phorusrhacid Titanis expanded northward into a southern North America during the Interchange and coexisted for several million years with large canids and big cats like Xenosmilus, before its extinction about 1.8 million years ago.
There were some suggestions that phorusrhacids, like the majority of Pleistocene megafauna, were killed off by human activity such as hunting or habitat change. This idea is no longer considered valid, as improved dating on Titanis specimens show that the last phorusrhacids went extinct over one million years before humans arrived.[9] However, several fossil finds of smaller forms have been described from the late Pleistocene of Uruguay in South America. Psilopterus may have been present until 96,040 ± 6,300 years ago (maximum age obtained from the bottom of the fossil-containing stratum), which would extend the existence of the smaller members of this group of avian predators considerably.[2] Another unidentified smaller type which may be a possible psilopterine[2] from the La Paz Local Fauna of Uruguay has also been dated to the late Pleistocene, perhaps 17,620 ± 100 years ago based on radiocarbon analysis using accelerator mass spectrometry (AMS) for the molar enamel samples of a proboscidean from the same site,[58] but the validity of this previous radiocarbon dating has been considered highly questionable due to the enamel's lack of collagen;[59] the tibia of Macrauchenia patachonica from the same site has been more precisely dated to a mean value of approximately 21,600 ± 1,000 years ago based on gamma spectrometry and radiocarbon dating.[60]
Notes
↑ It has been suggested that psilopterines like Psilopterus may have been able to fly briefly in a clumsy manner, primarily to reach the treetops for nesting and protection, on the basis of body mass estimates and hindlimb proportions being similar to those of certain birds like Psophia and Otis which often walk but are able to run and fly.[4][1]
↑ To be specific, this is the maximum age obtained from the bottom of the fossil-containing stratum.[2]
Related Research Articles
The seriemas are the sole living members of the small bird family Cariamidae, which is also the only surviving lineage of the order Cariamiformes. Once believed to be related to cranes, they have been placed near the falcons, parrots, and passerines, as well as the extinct Phorusrhacidae. The seriemas are large, long-legged territorial birds that range from 70–90 cm (28–35 in) in length. They live in grasslands, savanna, dry woodland and open forests of Brazil, Bolivia, Argentina, Paraguay and Uruguay. There are two species of seriemas, the red-legged seriema and the black-legged seriema. Names for these birds in the Tupian languages are variously spelled as siriema, sariama, and çariama, and mean "crested".
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.
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.
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.
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.
Strigogyps is an extinct genus of prehistoric bird from the Middle Eocene to Early Oligocene of France and Germany. It was probably around the size of a large chicken or a guan, weighing not quite 1 kilogram (2.2 lb). Apparently, as indicated by the ratio of lengths of wing to leg bones, S. sapea was flightless. Its legs were not adapted to running, so it seems to have had a walking lifestyle similar to trumpeters. Unlike other Cariamiformes which appear to have been mostly carnivorous, the specimens of one species, Strigogyps sapea, suggest a facultatively herbivorous or omnivorous diet.
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.
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.
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.
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.
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.
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.
Psilopterus is an extinct genus of phorusrhacid 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 and weighed about 5 kilograms (11 lb), while the largest members of the genus were only about 8 kilograms (18 lb). The birds resemble the modern cariama, except with a heavier build and considerably smaller wings. 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.
Lavocatavis is an extinct genus of prehistoric bird from the Eocene of Algeria. A fossilized femur was described from the Glib Zegdou Formation in 2011 and is the only known specimen of Lavocatavis. The species was designated L. africana.
Cariamiformes is an order of primarily flightless birds that has existed for over 50 million years. The group includes the family Cariamidae (seriemas) and the extinct families such as Phorusrhacidae, Bathornithidae, Idiornithidae and Ameghinornithidae. Extant members (seriemas) are only known from South America, but fossils of many extinct taxa are also found in other continents including Europe and North America. Though traditionally considered a suborder within Gruiformes, both morphological and genetic studies show that it belongs to a separate group of birds, Australaves, whose other living members are Falconidae, Psittaciformes and Passeriformes.
Llallawavis scagliai is a large, extinct predatory bird from Pliocene Argentina. Its fossil is the most complete fossil of a phorusrhacid yet found.
Bathornithidae is an extinct family of birds from the Eocene to Miocene of North America. Part of Cariamiformes, they are related to the still extant seriemas and the extinct Phorusrhacidae. They were likely similar in habits, being terrestrial, long-legged predators, some of which attained massive sizes.
Paracrax is a genus of extinct North American flightless birds, possibly related to modern seriemas and the extinct terror birds. Part of Bathornithidae, it is a specialised member of this group, being cursorial carnivores much like their South American cousins, some species attaining massive sizes.
Bathornis is an extinct lineage of birds related to modern day seriemas, that lived in North America about 37–20 million years ago. Like the closely related and also extinct phorusrhacids, it was a flightless predator, occupying predatory niches in environments classically considered to be dominated by mammals. It was a highly diverse and successful genus, spanning a large number of species that occurred from the Priabonian Eocene to the Burdigalian Miocene epochs.
Elaphrocnemus is a genus of extinct bird from the Eocene and Oligocene periods of Europe. Part of Cariamiformes, its closest living relatives are seriemas, though it differs significantly from them, being a better flyer.
References
1 2 3 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. S2CID267475903.
↑ Ameghino, F (1889). "Contribuición al conocimiento de los mamíferos fósiles de la República Argentina" [Contribution to the knowledge of fossil mammals in the Argentine Republic]. Actas Academia Nacional Ciencias de Córdoba (in Spanish). 6: 1–1028.
↑ 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.
1 2 3 MacFadden, Bruce J.; Labs-Hochstein, Joann; Hulbert, Richard C.; Baskin, Jon A. (2007). "Revised age of the late Neogene terror bird (Titanis) in North America during the Great American Interchange". Geology. 35 (2): 123–126. Bibcode:2007Geo....35..123M. doi:10.1130/G23186A.1. S2CID67762754.
1 2 3 Mayr, G. (2017). "Cariamiforms and Diurnal Birds of Prey". Avian Evolution: The Fossil Record of Birds and its Paleobiological Significance. Chichester: Wiley-Blackwell. pp.189–204. ISBN978-1119020769.
1 2 Mayr, G. (2022). "Accipitriformes (New World Vultures, Hawks, and Allies), Falconiformes (Falcons), and Cariamiformes (Seriemas and Allies)". Paleogene Fossil Birds. Fascinating Life Sciences. Springer Cham. pp.153–176. doi:10.1007/978-3-030-87645-6_8. ISBN978-3-030-87644-9.
1 2 3 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. PMC11040249. PMID38654650. Supplementary Information
1 2 Cracraft, J. (1968). "A review of the Bathornithidae (Aves, Gruiformes), with remarks on the relationships of the suborder Cariamae". American Museum Novitates (2326): 1–46. hdl:2246/2536.
↑ Agnolin, Federico L. (2009). Sistemática y Filogenia de las Aves Fororracoideas (Gruiformes, Cariamae)[Systematics and Phylogeny of Phororrhacoid Birds (Gruiformes, Cariamae)] (in Spanish). Fundación de Historia Natural Felix de Azara. pp.1–79.
↑ Bertelli, Sara; Chiappe, Luis M; Tambussi, Claudia (2007). "A New Phorusrhacid (Aves: Cariamae) from the Middle Miocene of Patagonia, Argentina". Journal of Vertebrate Paleontology. 27 (2): 409–419. doi:10.1671/0272-4634(2007)27[409:ANPACF]2.0.CO;2. S2CID85693135.
↑ Antón, Mauricio (2013). Sabertooth. Bloomington, Indiana: University of Indiana Press. p.61. ISBN9780253010421.
↑ 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. S2CID86790415.
↑ King, Logan; Barrick, Reese (October 2016). Semicircular canal shape within Aves and non-avian Theropoda: Utilizing geometric morphometrics to correlate life history with canal cross-sectional shape. Society of Vertebrate Paleontology 76th Annual Meeting At: Salt Lake City, Utah, United States.
↑ Ameghino, Florentino (1936). Torcelli, A.J. (ed.). Obras completas y correspondencia cientifica de Florentino Ameghino. Vol.21. La Plata: Taller de Impresiones Oficiales. p.573.
↑ Nasif, Norma L.; Esteban, Graciela I.; Ortiz, Pablo E. (2009). "Novedoso hallazgo de egagrópilas en el Mioceno tardío, Formación Andalhuala, provincia de Catamarca, Argentina". Serie Correlación Geológica. 25 (105–114).
↑ Federico L. Agnolin & Pablo Chafrat (2015). "New fossil bird remains from the Chichinales Formation (Early Miocene) of northern Patagonia, Argentina". Annales de Paléontologie. 101 (2): 87–94. Bibcode:2015AnPal.101...87A. doi:10.1016/j.annpal.2015.02.001.
1 2 Federico J. Degrange; Claudia P. Tambussi; Matías L. Taglioretti; Alejandro Dondas; Fernando Scaglia (2015). "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. S2CID85212917.
↑ Prevosti, Francisco J; Forasiepi, Analía; Zimicz, Natalia (2013). "The Evolution Of The Cenozoic Terrestrial Mammalian Predator Guild In South America: Competition Or Replacement?". Journal of Mammalian Evolution. 20 (1): 3–21. doi:10.1007/s10914-011-9175-9. hdl:11336/2663. S2CID15751319.
↑ Cid, A.S.; Anjos, R.M.; Zamboni, C.B.; Cardoso, R.; Muniz, M.; Corona, A.; Valladares, D.L.; Kovacs, L.; Macario, K.; Perea, D.; Goso, C.; Velasco, H. (2014). "Na, K, Ca, Mg, and U-series in fossil bone and the proposal of a radial diffusion–adsorption model of uranium uptake". Journal of Environmental Radioactivity. 136: 131–139. Bibcode:2014JEnvR.136..131C. doi:10.1016/j.jenvrad.2014.05.018. hdl:11336/5799. PMID24953228.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
