Andalgalornis

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Andalgalornis
Temporal range: Late Miocene (Huayquerian)
~9.0–6.8  Ma
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Skull of Andalgalornis steulleti.png
CT scan of the skull of P 14357, holotype of A. ferox in the collections of the Field 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: Patagornithinae
Genus: Andalgalornis
Patterson & Kraglievich, 1960
Species:
A. steulleti
Binomial name
Andalgalornis steulleti
(Kraglievich, 1931)
Synonyms
List

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

Contents

Taxonomy

Andalgalornis is known from an incomplete skeleton and some single bones found from sites in the Entre Ríos and Catamarca Provinces of northeast and northwest Argentina. The fossils were uncovered from the Late Miocene (Huayquerian in the SALMA classification) Ituzaingó Formation of the Paraná Basin. [1]

The following cladogram shows the position of Andalgalornis following a 2015 analysis: [2]

Phorusrhacidae

Description

Life restoration Andalgalornis jconway.png
Life restoration

Around 1.4 metres (4.6 ft) tall in height, Andalgalornis is estimated to have weighed around 40 kilograms (88 lb), [3] on the basis of the methodology proposed by Campbell and Marcus (1992). [4] The subfamily to which the genus belonged, the Patagornithinae, contained species that were of quite slender build; it looked much like the larger phorusrhacid Phorusrhacos , but it was more elegant and smaller and had a proportionally higher beak, the most massive in proportion to body size of all phorusrhacids.

Paleobiology

Phorusrhacids are thought to have been ground predators or scavengers, and have often been considered apex predators that dominated Cenozoic South America in the absence of mammalian predators, though they did co-exist with some large, carnivorous borhyaenid mammals. Earlier hypotheses of phorusrhacid feeding ecology were mainly based on them possessing large skulls with hooked beaks rather than through detailed hypotheses and biomechanical studies, and such studies of their running and predatory adaptations were only tested from the beginning of the 21st century. [3] [5]

Alvarenga and Elizabeth Höfling made some general remarks about phorusrhacid habits in a 2003 article. They were flightless, as evidenced by the proportional size of their wings and body mass, and wing size was more reduced in larger members of the group. They pointed out that the narrowing of the pelvis, upper maxilla, and thorax may have been adaptations for hunting in regions with high vegetation, which would permit greater agility when moving between vertical obstacles. The narrow upper maxilla would also help catching small animals hidden among tree trunks or stones. The large expansions above the eyes formed by the lacrimal bones (similar to what is seen in modern hawks) would have protected the eyes against the sun, and enabled keen eyesight, which indicates they hunted by sight in open, sunlit areas, and not shaded forests. [6]

Stress distribution in bird skulls.png
Andalgalornis neck range.png
Stress distribution in bird skulls, including Andalgalornis (left, A–C), and hypothetical upwards-and-downwards range of movement of the neck in the same genus (right)

A 2010 study by Degrange and colleagues of Andalgalornis, based on Finite Element Analysis using CT scans, estimated its bite force and stress distribution in its 37-centimetre-long (15 in) skull, and showed that it had lost a large degree of intracranial immobility (mobility of skull bones in relation to each other), as was also the case for other large phorusrhacids. These researchers interpreted this loss as an adaptation for enhanced rigidity of the skull, and compared to the modern red-legged seriema and white-tailed eagle, the skull of the phorusrhacid showed relatively high stress under sideways loadings, but low stress where force was applied up and down, and in simulations of "pullback". Due to the relative weakness of the skull at the sides and middle, these researchers considered it unlikely that Andalgalornis engaged in potentially risky behavior that involved using its beak to subdue large, struggling prey. Instead, they suggested that it either fed on smaller prey that could be killed and consumed more safely, by, for example, swallowing it whole, or that when targeting large prey, it used a series of well-targeted repetitive strikes with the beak, in an "attack-and-retreat" strategy. Struggling prey could also be retained with the feet, despite the lack of sharp talons. [3]

A 2012 follow-up study by Tambussi and colleagues analyzed the flexion abilities of the neck of Andalgalornis, based on the morphology of its neck vertebrae, finding the neck to be divided into three sections. They concluded that the neck musculature and skeleton of Andalgalornis was adapted to carrying a large head, and for helping it rise after a maximum downwards strike, and the researchers assumed the same would be true for other large, big-headed phorusrhacids. [7] A 2020 study of phorusrhacid skull morphology by Degrange found that there were two main morphotypes within the group, derived from a seriema-like ancestor; the "Psilopterine Skull Type", which was plesiomorphic (more similar to the ancestral type), and the "Terror Bird Skull Type", which included Andalgalornis and other large members, that was more specialized, with more rigid and stiff skulls. Despite the differences, studies have shown the two types handled prey similarly, while the more rigid skulls and resulting larger bite force of the "Terror Bird" type would have been an adaptation to handling larger prey. [5]

Related Research Articles

<span class="mw-page-title-main">Seriema</span> Family of birds

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".

<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>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>Scalabrinitherium</i> Extinct genus of litopterns

Scalabrinitherium is an extinct genus of mammals of the family Macraucheniidae. Fossils of this animal were found among the fossils of prehistoric xenarthrans in the Ituzaingó Formation of 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>Psilopterus</i> Extinct genus of birds

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.

<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.

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

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.

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

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.

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.

References

  1. Paraná, Pueblo Brugo to Diamante, Ituzaingó Fm at Fossilworks.org
  2. Degrange, Federico J.; Tambussi, Claudia P.; Taglioretti, Matías L.; Dondas, Alejandro; Scaglia, Fernando (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 . S2CID   85212917.
  3. 1 2 3 Degrange, Federico J.; Tambussi, Claudia P.; Moreno, Karen; Witmer, Lawrence M.; Wroe, Stephen (2010). "Mechanical Analysis of Feeding Behavior in the Extinct "Terror Bird" Andalgalornis steulleti (Gruiformes: Phorusrhacidae)". PLOS ONE. 5 (8): e11856. Bibcode:2010PLoSO...511856D. doi: 10.1371/journal.pone.0011856 . PMC   2923598 . PMID   20805872.
  4. Campbell, K.E.; Marcus, L. (1992). "The relationship of hindlimb bone dimensions to body weight in birds". Papers in Avian Paleontology Honoring Pierce Brodkorb. 36. Natural History Museum of Los Angeles County, Science Series: 395–412.
  5. 1 2 Degrange, Federico J. (2020). "A revision of skull morphology in Phorusrhacidae (Aves, Cariamiformes)". Journal of Vertebrate Paleontology. 40 (6): e1848855. Bibcode:2020JVPal..40E8855D. doi:10.1080/02724634.2020.1848855. S2CID   234119602.
  6. Alvarenga, Herculano M.F.; Höfling, Elizabeth (2003). "Systematic revision of the Phorusrhacidae (Aves: Ralliformes)". Papéis Avulsos de Zoologia. 43 (4). doi: 10.1590/S0031-10492003000400001 .
  7. Tambussi, Claudia P.; de Mendoza, Ricardo; Degrange, Federico J.; Picasso, Mariana B. (2012). "Flexibility along the Neck of the Neogene Terror Bird Andalgalornis steulleti (Aves Phorusrhacidae)". PLOS ONE. 7 (5): e37701. Bibcode:2012PLoSO...737701T. doi: 10.1371/journal.pone.0037701 . PMC   3360764 . PMID   22662194.

Further reading