Teratornithidae is an extinct

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

of very large

birds of prey Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predators ...

that lived in North and South America from the

Late Oligocene The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/ Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

to the

Late Pleistocene The Late Pleistocene is an unofficial Age (geology), age in the international geologic timescale in chronostratigraphy, also known as Upper Pleistocene from a Stratigraphy, stratigraphic perspective. It is intended to be the fourth division of ...

. They include some of the largest known flying birds.

Taxonomy

Teratornithidae are related to

New World vulture The New World vulture or condor family, Cathartidae, contains seven extant species in five genera. It includes five extant vultures and two extant condors found in warm and temperate areas of the Americas. The "New World" vultures were widespread ...

s (Cathartidae, syn. Vulturidae). So far, at least seven species in six genera have been identified: * ''

Teratornis ''Teratornis'' (Greek: "wonder" (teretos), "bird" (ornis)) was a genus of huge North American birds of prey – the best-known of the teratorns - of which, two species are known to have existed: ''Teratornis merriami'' and ''Teratornis woodburnen ...

'' ** ''Teratornis merriami''. This is by far the best-known species. Over 100 specimens have been found, mostly from the

La Brea Tar Pits La Brea Tar Pits is an active paleontological research site in urban Los Angeles. Hancock Park was formed around a group of tar pits where natural asphalt (also called asphaltum, bitumen, or pitch; ''brea'' in Spanish) has seeped up from the gro ...

. It stood about tall with an estimated wingspan of perhaps , and weighed about ; making it about a third bigger than extant condors. It became extinct at the end of the Pleistocene, some 10,000 years ago. ** ''Teratornis woodburnensis''. The first species to be found north of the La Brea Tar Pits, this partial specimen was discovered at Legion Park, Woodburn, Oregon. It is known from a humerus, parts of the cranium, beak, sternum, and vertebrae which indicate an estimated wingspan of over . The find dates to the Late Pleistocene, between 11,000 and 12,000 years ago, in a stratum which is filled with the bones of mastodons, sloths, and condors, and bears evidence of human habitation. * '' Aiolornis incredibilis'', previously known as ''Teratornis incredibilis''. This species is fairly poorly known; finds from Nevada and California include several wing bones and part of the beak. They show remarkable similarity with ''merriami'' but are uniformly about 40% larger: this would translate to a mass of up to and a wingspan of about for ''incredibilis''. The finds are dated from the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Cathartornis gracilis''. This species is known only from a couple of leg bones found from La Brea Ranch. Compared to ''T. merriami'', remains are slightly shorter and clearly more slender, indicating a more gracile build. * '' Argentavis magnificens''. A partial skeleton of this enormous teratorn was found from La Pampa, Argentina. It is one of the largest flying birds known to have existed, only likely exceeded by measurement of wingspan by '' Pelagornis sandersi'', discovered in 1983. Fossil remains of this species have been dated to Late Miocene, about 6 to 8 million years ago, and one of the few teratorn finds in South America. Initial discovery included portions of the skull, incomplete humerus and several other wing bones. Even conservative estimates put its wingspan at and up, and it may have been as much as . The weight of the bird was estimated to have been around . * Another form, '' "Teratornis" olsoni'', was described from the Pleistocene of

Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...

, but its affinities are not completely resolved; it might not be a teratorn at all, but has also been placed in its own genus, ''

Oscaravis ''Oscaravis olsoni'' (also known as the Cuban teratorn), of the Teratornithidae, teratorn family, was a large, predatory bird that roamed the territory that is now modern-day Cuba before going extinct at the end of the Pleistocene era. Previously ...

''. There are also undescribed fossils from southwestern

Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...

. * '' Taubatornis campbelli'' is the earliest known teratorn species, from the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 Ma to 15.97 ± 0.05 Ma (million years ago). It was prece ...

of the

Tremembé Formation Tremembé is a municipality in the state of São Paulo in Brazil. It is part of the Metropolitan Region of Vale do Paraíba e Litoral Norte. The population is 47,714 (2020 est.) in an area of 191.09 km². The elevation is 560 m. A shr ...

Taubaté Basin Taubaté is a medium-sized city in the State of São Paulo, in southeastern Brazil. Location Its strategic location between the two most important Brazilian cities (São Paulo away, and Rio de Janeiro away), connected to both by the Presiden ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Description and ecology

Despite their size, there is little doubt that even the largest teratorns could fly. Visible marks of the attachments of contour feathers can be seen on ''Argentavis'' wing bones. This defies some earlier theories that modern condors,

swan Swans are birds of the family (biology), family Anatidae within the genus ''Cygnus''. The swans' closest relatives include the goose, geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form t ...

s, and

bustard Bustards, including floricans and korhaans, are large, terrestrial birds living mainly in dry grassland areas and on the steppes of the Old World. They range in length from . They make up the family Otididae (, formerly known as Otidae). Bustards ...

s represent the size limit for flying birds. The

wing loading In aerodynamics, wing loading is the total mass of an aircraft or flying animal divided by the area of its wing. The stalling speed of an aircraft in straight, level flight is partly determined by its wing loading. An aircraft or animal with a ...

of ''Argentavis'' was relatively low for its size, a bit more than a

turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...

's, and if there were any significant wind present, the bird could probably get airborne merely by spreading its wings, just like modern

albatross Albatrosses, of the biological family Diomedeidae, are large seabirds related to the procellariids, storm petrels, and diving petrels in the order Procellariiformes (the tubenoses). They range widely in the Southern Ocean and the North Pacifi ...

es. South America during the Miocene probably featured strong and steady westerly winds, as the

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

were still forming and not yet very high. ''T. merriami'' was small enough (relatively speaking) to take off with a simple jump and a few flaps. The fingerbones are mostly fused as in all birds, but the former

index finger The index finger (also referred to as forefinger, first finger, second finger, pointer finger, trigger finger, digitus secundus, digitus II, and many other terms) is the second digit of a human hand. It is located between the thumb and the mid ...

has partially evolved into a wide shelf at least in ''T. merriami'', and as condors have a similar adaptation, probably in other species, too. Wing length estimates vary considerably but more likely than not were at the upper end of the range, because this bone structure bears the load of the massive primaries. Studies on

condor Condor is the common name for two species of New World vultures, each in a monotypic genus. The name derives from the Quechua ''kuntur''. They are the largest flying land birds in the Western Hemisphere. They are: * The Andean condor (''Vult ...

flight suggest that even the largest teratorns were capable of flight in normal conditions, as modern large soaring birds rarely flap their wings regardless of terrain. Traditionally, teratorns have been described as large scavengers, very much like oversized condors, owing to considerable similarity with condors. However, the long beaks and wide gapes of teratorns are more like the beaks of

eagle Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...

s and other actively predatory birds than those of vultures. Most likely teratorns swallowed their prey whole; ''Argentavis'' could technically swallow up to

hare Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores, and live solitarily or in pairs. They nest in slight depressions called forms, and their young are able to fend for themselves shortly after birth. The ge ...

-sized animals in a single piece. Although they undoubtedly engaged in opportunistic

scavenging Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding be ...

, they seem to have been active

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

s most of the time. Teratorns had relatively longer and stouter legs than Old World vultures; thus it seems possible that teratorns would stalk their prey on the ground (much like extant

caracaras Caracaras are birds of prey in the family Falconidae. They are traditionally placed in subfamily Polyborinae with the forest falcons, but are sometimes considered to constitute their own subfamily, Caracarinae, or classified as members of t ...

), and take off only to fly to another feeding ground or their nests; especially ''Cathartornis'' seems well-adapted for such a lifestyle. ''Argentavis'' may have been an exception, as its sheer bulk would have made it a less effective hunter, but better adapted to taking over other predators' kills. As teratorns were not habitual scavengers, they most likely had completely feathered heads, unlike

vulture A vulture is a bird of prey that scavenges on carrion. There are 23 extant species of vulture (including Condors). Old World vultures include 16 living species native to Europe, Africa, and Asia; New World vultures are restricted to North and ...

s. It should be noted, however, that the skull features of teratorns still share a lot of crucial similarities with specialized scavenging raptors. Many

old world vultures Old World vultures are vultures that are found in the Old World, i.e. the continents of Europe, Asia and Africa, and which belong to the family Accipitridae, which also includes eagles, buzzards, kites, and hawks. Old World vultures are not clo ...

possess large bills similar to teratorns, and a longer bill is in fact an anatomic feature that points toward a scavenging rather than a predatory life style, as this allow them to probe deeper into large carcases - larger than those fed upon by active-hunting raptors. Other anatomical features, such as the relatively small and sideward facing orbits and the lower skull, are also consistent with a scavenging live style. More sideward facing eyes allow scavenging raptors to have a wider field of vision, which is advantageous in spotting carcases. In contrast, predatory raptors usually have proportionally larger and more forward facing orbits, as depth perception is more important for a predatory lifestyle. As in other large birds, a

clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...

probably had only one or two eggs; the young would be cared for more than half a year, and take several years to reach maturity, probably up to 12 years in ''Argentavis''.

References

External links

Vulture Territory Facts and Characteristics: Teratorns
{{Taxonbar, from=Q135217 Prehistoric bird families † New World vultures Oligocene birds Miocene birds Pliocene birds Pleistocene birds Oligocene first appearances Pleistocene extinctions Neogene birds of North America Neogene birds of South America Pleistocene birds of North America Pleistocene animals of South America Taxa named by Loye H. Miller