Phorusrhacidae
Phorusrhacidae | |
---|---|
Reconstructed skeleton of Titanis walleri, Florida Museum of Natural History | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Cariamiformes |
Superfamily: | † Phorusrhacoidea , 1889
Ameghino |
Family: | †Phorusrhacidae Ameghino, 1889[2] |
Type species | |
† Phorusrhacos longissimus Ameghino, 1887
| |
Subfamilies | |
| |
Synonyms | |
Family synonymy
|
Phorusrhacids, colloquially known as terror birds, are an extinct family of large carnivorous flightless birds that were among the largest apex predators in South America during the Cenozoic era; their conventionally accepted temporal range covers from 53 to 0.1 million years (Ma) ago.[1]
They ranged in height from 1 to 3 m (3 to 10 ft). Their closest modern-day relatives are believed to be the 80-centimetre-tall (31 in) 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 Panama land bridge (the main pulse of the interchange began about 2.6 Ma ago; Titanis at 5 Ma was an early northward migrant).[3]
It was once believed that T. walleri became extinct in North America around the time of the arrival of humans,[4] but subsequent datings of Titanis fossils provided no evidence for their survival after 1.8 Ma.[5] However, reports from Uruguay of new findings of a relatively small form (Psilopterus) dating to 18,000[6] and 96,000[7] years ago would imply that phorusrhacids survived there until very recently (i.e., until the late Pleistocene); the initial report of such a recent date has been questioned.[8]
Phorusrhacids may have even made their way into Africa; the genus Lavocatavis was discovered in Algeria, but its status as a true phorusrhacid is questioned.[9] The possible European form (Eleutherornis) and possible Antarctic specimens have also been identified, suggesting that this group had a wider geographical range in the Paleogene.[10][11][12]
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.[13][14] At least one analysis recovers Bathornis as sister taxa to phorusrhacids, on the basis of shared features in the jaws and coracoid,[15] though this has been seriously contested, as these might have evolved independently for the same carnivorous, flightless lifestyle.[16]
Description
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.[17]
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 (28 in), nearly intact skull. The beak is roughly 46 cm (18 in) long and curves in a hook shape that resembles an eagle's beak. Most species described as phorusrhacid birds were smaller, 60–90 cm (2.0–3.0 ft) tall, but the new fossil belongs to a bird that probably stood about 3 m (9.8 ft) tall. Scientists theorize that the large terror birds were extremely nimble and quick runners, able to reach speeds of 48 km/h (30 mph).[18] 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.[19]
The feet of the phorusrhacids had four toes, the first of which, known as the
Skull structure
In the past, these birds were thought to have high beaks, round orbits, and vaulted braincases[22] 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.[22] The structure of the fossils also suggest that these birds may have been swifter than originally thought.[22]
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.[23]
Palaeobiology
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.[24][25] 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,[26] 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.[27]
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.
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.[32] 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
Phylogenetic analysis of Cariamiformes and their relatives according to Mayr (2016) in his redescription of Bathornis:[36]
| |||||||||||||||||||||||||||||||
Following the revision by Alvarenga and Höfling (2003), there are now 5 subfamilies, containing 14 genera and 18 species:[37] These species were the product of adaptive radiation.[38]
Superfamily Phorusrhacoidea
- Genus Lavocatavis – Middle Eocene Glib Zegdou Formation of Algeria
Family Phorusrhacidae
- Genus Patagorhacos – Early Miocene Chichinales Formation of Rio Negro Province, Argentina.[39]
- Subfamily Brontornithinae — gigantic species, standing on average 8.6 feet (2.6 m) high. Placement in Phorusrhacidae and/or monophyly disputed.
- Genus Santa Cruz and Monte León Formations, Argentina)
- Genus Paraphysornis (Late Oligocene to Early Miocene (Deseadan) Tremembé Formation of São Paulo State, Brazil)
- Genus Physornis (Middle to Late Oligocene (Deseadan) Sarmiento Formation of Santa Cruz Province, Argentina)
- Genus
- Subfamily Phorusrhacinae — giant species 8.3 feet (2.5 m) high (Kelenken up to 9.8 feet (3.0 m) high[40]), but somewhat slender and decidedly more nimble than the Brontornithinae
- Genus Devincenzia (Late Oligocene to Early Miocene (Deseadan) Fray Bentos Formation of Uruguay)
- Genus Kelenken (Middle Miocene (Colloncuran) Collón Curá Formation of Río Negro Province, Argentina; largest known phorusrhacid)
- Genus Santa Cruz Formationof Argentina)
- Genus Titanis (Early Pliocene to Early Pleistocene (Blancan) of Florida, California, and Texas)[5][41]
- Subfamily Patagornithinae — intermediate sized and very nimble species, standing around 5.4 feet (1.6 m) high
- Genus Santa Cruz Formationof Santa Cruz Province, Argentina) – includes Morenomerceraria, Palaeociconia, Tolmodus
- Genus Andrewsornis (Middle to Late Oligocene (Deseadan) Agua de la Piedra Formation of southern Argentina)
- Genus Andalgalornis (Late Miocene to Early Pliocene (Huayquerian) Ituzaingó Formation of northwestern Argentina)
- Genus
- Subfamily Psilopterinae — small species, standing 3.2 feet (0.98 m) high
- Genus Eleutherornis (Middle Eocene (Bartonian) of Rhône, France and Baselland, Switzerland)[11]
- Genus ?Paleopsilopterus (Lower Eocene (Itaboraian) Itaboraí Formation of Itaboraí, Brazil) (identity as a phorusrhacid dubious)[11][42]
- Genus Santa Cruz Formation and Late Miocene (Chasicoan) Arroyo Chasicó Formation of southern and eastern Argentina respectively) (Possible Late Pleistocene (Lujanian) records from Uruguay)
- Subfamily Mesembriornithinae — medium-sized species, standing 4.4 feet (1.3 m) high
- Genus Mesembriornis (Late Miocene to Late Pliocene (Montehermosan) Monte Hermoso Formation of Argentina)
- Genus Procariama (Late Miocene to Early Pliocene (Huayquerian-Montehermosan) Cerro Azul and Andalhualá Formations of Catamarca Province, Argentina)
- Genus Llallawavis (Late Pliocene (Chapadmalalan) Playa Los Lobos Allo Formation of northeastern Argentina)[43]
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.[44] Though traditionally considered as members of the Gruiformes, based on both morphological and genetic studies (the latter being based on the seriema[45]) 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.[46][47]
The following cladogram follows the analysis of Degrange and colleagues, 2015:[43]
Phorusrhacidae |
|
Physornithinae Phorusrhacinae Patagornithinae | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Extinction
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.[48] (They had been preceded by procyonids as early as 7.3 million years ago.[3]) The population of phorusrhacids declined thereafter according to older hypotheses, suggesting that competition with newly arrived predators was a major contributor to their extinction.[49] Similar ideas have been considered for sparassodonts and for South America's terrestrial sebecid crocodilians.[50]
However, the role of competitive displacement in South American predator lineages has been questioned by some researchers.
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.[5] However, several fossil finds of smaller forms have been described from the late Pleistocene of South America. Psilopterus may have been present until 96,040 ± 6,300 years ago.[7] Another unidentified smaller type has also been dated to the late Pleistocene, perhaps 18,000 years ago.[6] These finds, if accepted, extend the existence of the smaller members of this group of avian predators considerably.
References
- ^ S2CID 134344096.
- ^ 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.
- ^ PMID 21125025.
- .
- ^ S2CID 67762754.
- ^ .
- ^ S2CID 134344096. Note: their date of 96 thousand years BP is the maximum age, obtained from the bottom of the fossil-containing stratum.
- ISSN 1853-0400.
- S2CID 19805809.
- ^ Angst, Delphine; Buffetaut, Eric (2012). "A Large Phorusrhacid Bird From the Middle Eocene of France". 8th International Meeting of the Society of Avian Paleontology and Evolution (PDF). p. 9. Archived from the original (PDF) on 2019-12-06.
- ^ PMID 24312212.
- doi:10.26879/1340.
- ISBN 978-0253016089.
- ^ 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.
- hdl:11336/41730.
- PMID 22662194.
- S2CID 85693135.
- ISBN 9780253010421.
- ^ Jones, Washington W. (2010). Nuevos aportes sobre la paleobiología de los fororrácidos (Aves: Phorusrhacidae) basados en el análisis de estructuras biológicas [New contributions on the paleobiology of phororrhacids (Aves: Phorusrhacidae) based on the analysis of biological structures] (PDF) (PhD thesis) (in Spanish). Uruguay: Universidad de la República - Facultad de Ciencias.
- PMID 37777554.
- ^ S2CID 4381103.
- S2CID 86790415.
- ^ Bakker, Robert; et al. (1998). "Brontosaur Killers: Late Jurassic Allosaurids as Sabre-tooth Cat Analogues". GAIA. 15 (8): 145–158.
- ^ Nash, Duane (2015-09-02). "Terror Birds Cometh: A New Hypothesis Unlocking Phorusrhacid Feeding Dynamics & Ecology". Antediluvian Salad.
- PMID 20805872.
- ^ 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.
- ^ "Ancient "terror bird" used powerful beak to jab like an agile boxer". OHIO: Research. Aug 18, 2010. Archived from the original on 2017-05-16.
- ^ 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.
- ^ OCLC 1012400051.
- ^ 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).
- ^ Creisler, Ben (2012-06-26). "Phorusrhacos "wrinkle bearer (jaw)": Etymology and Meaning". usc.edu dinosaur (Mailing list). Archived from the original on 2016-03-04.
- . Retrieved 11 May 2023.
- S2CID 234119602.
- ^ Cracraft, J. (1968). "A review of the Bathornithidae (Aves, Gruiformes), with remarks on the relationships of the suborder Cariamae". American Museum Novitates (2326).
- ^ S2CID 88936361.
- .
- .
- .
- S2CID 126914134.
- ^ Chandler, Robert M; Jefferson, George T; Lindsay, Lowell; Vescera, Susan P (2013-04-01). The Terror Bird, Titanis (Phorusrhacidae) from Pliocene Olla Formation, Anza-Borrego Desert State Park, Southern California (PDF). Raising Questions in the central Mojave Desert: The 2013 Desrt Symposium Field Guide and Proceedings. pp. 181–183. Archived from the original (PDF) on 2023-07-21.
- .
- ^ S2CID 85212917.
- ^ Mayr, Gerald (2005-04-15). "Old World phorusrhacids (Aves, Phorusrhacidae): a new look at Strigogyps ("Aenigmavis") sapea (Peters 1987)" (abstract). PaleoBios. 25 (1): 11–16. Retrieved 2008-07-04.
- S2CID 6472805.
- PMID 21863010.
- PMID 25504713. Archived from the original(PDF) on 2019-12-06. Retrieved 2018-05-27.
- S2CID 198152030.
- ISSN 0036-8733.
- JSTOR 4522967.
- ^ Naish, Darren (30 May 2001). "Dumb Metatherians vs Evil, Smart Placentals". USC dinosaur (Mailing list). Archived from the original on 2011-11-20.
- ISSN 1514-5158.
- S2CID 15751319.
External links
- Hooper Museum
- Terror Birds: Bigger and Faster (Science)
- Darren Naish: Tetrapod Zoology: "terror birds"
- Darren Naish: Tetrapod Zoology: "Raven, the claw-handed bird, last of the phorusrhacids" includes links to other articles on phorusrhacids