Argentavis
Encyclopedia
Argentavis magnificens (literally "magnificent Argentine bird") is the largest flying bird ever discovered. This bird, sometimes called the Giant Teratorn, is an extinct
species
known from three sites from the late Miocene
(6 million years before present) of central and northwestern Argentina
, where a good sample of fossil
s has been obtained.
The humerus
(upper arm bone) of Argentavis is somewhat damaged. Even so, it allows a fairly accurate estimate of its length in life, which was only slightly shorter than an entire human arm. The species apparently had stout, strong legs and large feet which enabled it to walk with ease. The bill was large, rather slender, and had a hooked tip with a wide gape.
For comparison, the living bird with the largest wingspan is the Wandering Albatross
, at 3.65 m (12 ft). Since A. magnificens is known to have been a land bird, another good point of comparison is the Andean Condor
, which is not too distantly related to Argentavis. This bird is among the largest land birds, with a wingspan of up to 3.2 m (10.5 ft) and weighing up to 15 kg (33.1 lb).
The ability to fly is not a simple question of weight ratios, except in extreme cases. Size and structure of the wing must also be taken into account. As a rule of thumb, a wing loading
of 25 kg/m² is considered the limit for avian flight.
The heaviest extant flying birds are known to weigh up to 21 kg (46.3 lb) (there are several contenders, among which are the European Great Bustard
and the African Kori Bustard
). A Mute Swan
, which may have briefly lost the power of flight due to its extreme weight, was found to have weighed 23 kg (50.7 lb). The Sarus Crane
is the tallest flying bird alive, at up to 2 m (6.6 ft) high, standing nearly as high as Argentavis due to its long legs and neck.
The largest known flying creatures are a group of pterosaur
s named azhdarchids
, extinct flying animals that existed during the age of the dinosaur
s and died out at the end of the Cretaceous
. Estimations of the wingspan of the largest species like Quetzalcoatlus
and Hatzegopteryx
exceeds 10 m (33 ft), with less conservative estimates being 12 m (40 ft) or more.
, scanning large areas of land from aloft for carrion. The climate of the Andean foothills in Argentina during the late Miocene was warmer and drier than today, which would have further aided the bird in staying aloft atop thermal updrafts.
This species seems less aerodynamically suited for predation
than its relatives. It probably preferred to scavenge for carrion, and it is possible that it habitually chased metatheria
n carnivores such as Thylacosmilidae
from their kills. Unlike extant condors and vultures, the other species of teratorns generally had long, eagle
-like beaks and are believed to have been active predators, being less ponderous than Argentavis. When hunting actively, A. magnificens would probably have swooped from high above onto their prey, which they usually would have been able to grab, kill, and swallow without landing. Skull structure suggests that it ate most of its prey whole rather than tearing off pieces of flesh.
Argentavis territories
measured probably more than 500 square km, which the birds screened for food, possibly utilizing a generally north-south direction to avoid being slowed by adverse winds. Comparison with extant birds suggests it laid one or two eggs with a mass of somewhat over 1 kg – somewhat smaller than an ostrich
egg – every two years. Climate considerations make it likely that the birds incubated over the winter, mates exchanging duties of incubating and procuring food every few days, and that the young were independent after some 16 months, but not fully mature until aged about a dozen years. Mortality must have been very low; to maintain a viable population less than about 2% of birds may have died each year. Of course, Argentavis suffered hardly any predation, and mortality was mainly from old age, accidents and disease.
It appears likely, therefore, that the average and maximum age reached by these creatures was fairly large – possibly some 50–100 years; compare with ostrich
at perhaps 60–70, and parrots at perhaps 80–120 at most – if they were to mature and reproduce and replace members that had died 'young' – for whatever reason. Presently, no direct evidence is available for this suggestion; however, K-strategy lifestyle correlates with greater average and maximum age.
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
known from three sites from the late Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
(6 million years before present) of central and northwestern Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, where a good sample of fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s has been obtained.
The humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
(upper arm bone) of Argentavis is somewhat damaged. Even so, it allows a fairly accurate estimate of its length in life, which was only slightly shorter than an entire human arm. The species apparently had stout, strong legs and large feet which enabled it to walk with ease. The bill was large, rather slender, and had a hooked tip with a wide gape.
Physical characteristics
Currently accepted estimates:- WingspanWingspanThe wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...
: 7 m (23 ft) - Wing area: nearly 7 m² (75 square ft)
- Wing loading: c. 11.5 kg/m²
- Length: 3.5 m (11.5 ft)
- Height: 1.7–2 m (5.6–6.6 ft)
- Mass: 70-78 kg (150-172 lb)
For comparison, the living bird with the largest wingspan is the Wandering Albatross
Wandering Albatross
The Wandering Albatross, Snowy Albatross or White-winged Albatross, Diomedea exulans, is a large seabird from the family Diomedeidae, which has a circumpolar range in the Southern Ocean. It was the first species of albatross to be described, and was long considered the same species as the Tristan...
, at 3.65 m (12 ft). Since A. magnificens is known to have been a land bird, another good point of comparison is the Andean Condor
Andean Condor
The Andean Condor is a species of South American bird in the New World vulture family Cathartidae and is the only member of the genus Vultur...
, which is not too distantly related to Argentavis. This bird is among the largest land birds, with a wingspan of up to 3.2 m (10.5 ft) and weighing up to 15 kg (33.1 lb).
The ability to fly is not a simple question of weight ratios, except in extreme cases. Size and structure of the wing must also be taken into account. As a rule of thumb, a wing loading
Wing loading
In aerodynamics, wing loading is the loaded weight of the aircraft divided by the area of the wing. The faster an aircraft flies, the more lift is produced by each unit area of wing, so a smaller wing can carry the same weight in level flight, operating at a higher wing loading. Correspondingly,...
of 25 kg/m² is considered the limit for avian flight.
The heaviest extant flying birds are known to weigh up to 21 kg (46.3 lb) (there are several contenders, among which are the European Great Bustard
Great Bustard
The Great Bustard is in the bustard family, the only member of the genus Otis. It breeds in southern and central Europe, where it is the largest species of bird, and across temperate Asia...
and the African Kori Bustard
Kori Bustard
The Kori Bustard is a large bird native to Africa. It is a member of the bustard family. It may be the heaviest bird capable of flight....
). A Mute Swan
Mute Swan
The Mute Swan is a species of swan, and thus a member of the duck, goose and swan family Anatidae. It is native to much of Europe and Asia, and the far north of Africa. It is also an introduced species in North America, Australasia and southern Africa. The name 'mute' derives from it being less...
, which may have briefly lost the power of flight due to its extreme weight, was found to have weighed 23 kg (50.7 lb). The Sarus Crane
Sarus Crane
The Sarus Crane is a large non-migratory crane found in parts of the Indian Subcontinent, Southeast Asia and Australia. The tallest of the flying birds, standing at a height of up to 1.8 m , they are conspicuous and iconic species of open wetlands...
is the tallest flying bird alive, at up to 2 m (6.6 ft) high, standing nearly as high as Argentavis due to its long legs and neck.
The largest known flying creatures are a group of pterosaur
Pterosaur
Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period . Pterosaurs are the earliest vertebrates known to have evolved powered flight...
s named azhdarchids
Azhdarchidae
Azhdarchidae is a family of pterosaurs known primarily from the late Cretaceous Period, though an isolated vertebrae apparently from an azhdarchid is known from the early Cretaceous as well...
, extinct flying animals that existed during the age of the dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
s and died out at the end of the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. Estimations of the wingspan of the largest species like Quetzalcoatlus
Quetzalcoatlus
Quetzalcoatlus was a pterodactyloid pterosaur known from the Late Cretaceous of North America , and one of the largest known flying animals of all time. It was a member of the Azhdarchidae, a family of advanced toothless pterosaurs with unusually long, stiffened necks...
and Hatzegopteryx
Hatzegopteryx
Hatzegopteryx is a genus of azhdarchid pterosaur, known from incomplete remains found in Transylvania. The skull fragments, left humerus, and other fossilized remains indicate it was among the largest pterosaurs. The skeleton of Hatzegopteryx has been considered identical to the known remains of...
exceeds 10 m (33 ft), with less conservative estimates being 12 m (40 ft) or more.
Ecology
As with nearly all extinct species, not much can be known about the Giant Teratorn's behaviour. From the size and structure of its wings it is inferred that A. magnificens flew mainly by soaring, using flapping flight only during short periods. It is probable that it used thermal currents as well. It has been estimated that the minimal velocity for the wing of A. magnificens is about 11 m/s or 40 km/h. Especially for takeoff, it would have depended on the wind, as although its legs were strong enough to provide it with a running or jumping start, the wings were simply too long to flap effectively until the bird was some meters off the ground. However, skeletal evidence suggests that its breast muscles were not powerful enough for wing flapping for extended periods. Argentavis may have used mountain slopes and headwinds to take off, and probably could manage to do so from even gently sloping terrain with little effort. It may have flown and lived much like the modern Andean condorAndean Condor
The Andean Condor is a species of South American bird in the New World vulture family Cathartidae and is the only member of the genus Vultur...
, scanning large areas of land from aloft for carrion. The climate of the Andean foothills in Argentina during the late Miocene was warmer and drier than today, which would have further aided the bird in staying aloft atop thermal updrafts.
This species seems less aerodynamically suited for predation
Predation
In ecology, predation describes a biological interaction where a predator feeds on its prey . Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of its prey and the eventual absorption of the prey's tissue through consumption...
than its relatives. It probably preferred to scavenge for carrion, and it is possible that it habitually chased metatheria
Metatheria
Metatheria is a grouping within the animal class Mammalia. First proposed by Thomas Henry Huxley in 1880, it is nearly synonymous with the earlier taxon Marsupialia though it is slightly wider since it also contains the nearest fossil relatives of marsupial mammals.The earliest known...
n carnivores such as Thylacosmilidae
Thylacosmilus
Thylacosmilus was a genus of sabre-toothed metatherian predators that first appeared during the Miocene. Remains of the animal have been found in parts of South America, primarily Argentina...
from their kills. Unlike extant condors and vultures, the other species of teratorns generally had long, eagle
Eagle
Eagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
-like beaks and are believed to have been active predators, being less ponderous than Argentavis. When hunting actively, A. magnificens would probably have swooped from high above onto their prey, which they usually would have been able to grab, kill, and swallow without landing. Skull structure suggests that it ate most of its prey whole rather than tearing off pieces of flesh.
Argentavis territories
Territory (animal)
In ethology the term territory refers to any sociographical area that an animal of a particular species consistently defends against conspecifics...
measured probably more than 500 square km, which the birds screened for food, possibly utilizing a generally north-south direction to avoid being slowed by adverse winds. Comparison with extant birds suggests it laid one or two eggs with a mass of somewhat over 1 kg – somewhat smaller than an ostrich
Ostrich
The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a...
egg – every two years. Climate considerations make it likely that the birds incubated over the winter, mates exchanging duties of incubating and procuring food every few days, and that the young were independent after some 16 months, but not fully mature until aged about a dozen years. Mortality must have been very low; to maintain a viable population less than about 2% of birds may have died each year. Of course, Argentavis suffered hardly any predation, and mortality was mainly from old age, accidents and disease.
It appears likely, therefore, that the average and maximum age reached by these creatures was fairly large – possibly some 50–100 years; compare with ostrich
Ostrich
The Ostrich is one or two species of large flightless birds native to Africa, the only living member of the genus Struthio. Some analyses indicate that the Somali Ostrich may be better considered a full species apart from the Common Ostrich, but most taxonomists consider it to be a...
at perhaps 60–70, and parrots at perhaps 80–120 at most – if they were to mature and reproduce and replace members that had died 'young' – for whatever reason. Presently, no direct evidence is available for this suggestion; however, K-strategy lifestyle correlates with greater average and maximum age.
External links
- BBC News: Ancient American bird was glider – BBC News article
- How the dinosaur bird took to the skies – Telegraph.co.uk article
- Secret of flight for world's largest bird revealed – COSMOS Magazine article
- Argentavis, the largest flying bird, was a master glider – Article from the blog Not Exactly Rocket Science