Teratornithidae
Encyclopedia
Teratorns were very large birds of prey
that lived in North and South America from Miocene
to Pleistocene
. They include some of the largest known flying birds. So far, at least four species have been identified:
A potentially new species, "Teratornis Woodburnensis", was reported in Pleistocene deposits in Oregon, although its designation is not yet confirmed. Another form, "Teratornis" olsoni, was described from the Pleistocene of Cuba
, but its affinities are not completely resolved; it might not be a teratorn at all. There are also undescribed fossils from southwestern Ecuador
, but apart from these forms, teratorns were restricted to North America (Campbell & Tonni, 1983).
Some cryptozoologists such as Ken Gerhard
, and Mark A. Hall have expressed interest in Teratorns as a possible explanation of anecdotal sightings of very large birds in Texas
and Illinois
and popularly known as Thunderbirds
.
s, and bustard
s represent the size limit for flying birds. The wing loading of Argentavis was relatively low for its size, a bit more than a turkey
's (Campbell & Tonni, 1983), and if there were any significant wind present, the bird could probably get airborne merely by spreading its wings, just like modern albatross
es. South America during the Miocene probably featured strong and steady westerly winds, as the Andes
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
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.
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
s and other actively predatory birds than those of vultures. Most likely teratorns swallowed their prey whole; Argentavis could technically swallow up to hare
-sized animals in a single piece. Although they undoubtedly engaged in opportunistic scavenging
, they seem to have been active predator
s most of the time (Campbell & Tonni, 1983). Teratorns had relatively longer and stouter legs than Old World vultures; thus it seems possible that teratorns would stalk their prey on the ground, 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
s.
As in other large birds, a clutch
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 a dozen in Argentavis (Palqvist & Vizcaíno, 2003).
Bird of prey
Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....
that lived in North and South America from 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...
to Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
. They include some of the largest known flying birds. So far, at least four species have been identified:
- Teratornis merriamiTeratornisTeratornis merriami was a huge North American teratorn, with a wingspan of around 3.5 to 3.8 meters and a wing area of 17.5 square meters, standing an estimated 75 cm tall and weighing about 15 kg. It was somewhat larger than the extant Andean Condor and nearly two double the weight of the...
(Miller, 1909). This is by far the best-known species. Over a hundred specimens have been found, mostly from La Brea Tar PitsLa Brea Tar PitsThe La Brea Tar Pits are a cluster of tar pits around which Hancock Park was formed, in the urban heart of Los Angeles. Asphaltum or tar has seeped up from the ground in this area for tens of thousands of years. The tar is often covered with water...
. It stood about 75 cm (29.5 in) tall with estimated wingspan of perhaps 3.5 to 3.8 metres (11.5 to 12.5 ft), and weighed about 15 kg (33 lb); making it slightly bigger than extant condors. It became extinct at the end of Pleistocene, some 10 000 years ago.
- Aiolornis incredibilisAiolornisAiolornis incredibilis , of the teratorn family, was the largest known North American flight-capable bird, with a wingspan of up to 17 feet and a huge, deep, powerful bill. A. incredibilis presumably became extinct at the same time as the other megafauna in North America...
(Howard, 1952), 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 23 kg (50 lb) and a wingspan of about 5.5 metres (18.04 ft) for incredibilis. The finds are dated from the PliocenePlioceneThe Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
to the late Pleistocene, which is considerable chronological spread, and thus it is uncertain whether they actually represent the same species.
- Cathartornis gracilis (Miller, 1910). 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 more gracile build.
- Argentavis magnificensArgentavisArgentavis magnificens 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 of central and northwestern Argentina, where a good sample of fossils has been obtained.The humerus of...
(Campbell & Tonni, 1980). A partial skeleton of this enormous teratorn was found from La Pampa, Argentina. It is the largest flying bird known to have existed. It is the oldest known teratorn, dating to late Miocene, about 6 to 8 million years ago, and one of the very 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 6 meters and up (some 20 ft), and it may have been as much as 8 metres (26 ft). The weight of the bird was estimated to have been around 80 kg (176 lb). The estimated weight and wing area rival those of the largest pterosaurPterosaurPterosaurs 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.
A potentially new species, "Teratornis Woodburnensis", was reported in Pleistocene deposits in Oregon, although its designation is not yet confirmed. Another form, "Teratornis" olsoni, was described from the Pleistocene of Cuba
Cuba
The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
, but its affinities are not completely resolved; it might not be a teratorn at all. There are also undescribed fossils from southwestern Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
, but apart from these forms, teratorns were restricted to North America (Campbell & Tonni, 1983).
Some cryptozoologists such as Ken Gerhard
Ken Gerhard
Ken Gerhard is an American cryptozoologist often featured on the History Channel, Travel Channel, A&E, National Geographic Channel and truTV...
, and Mark A. Hall have expressed interest in Teratorns as a possible explanation of anecdotal sightings of very large birds in Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
and Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
and popularly known as Thunderbirds
Thunderbird (cryptozoology)
Thunderbird is a term used in cryptozoology to describe large, bird-like creatures, generally identified with the Thunderbird of Native American tradition. Similar cryptids reported in the Old World are often called Rocs. Thunderbirds are regarded by a small number of researchers as having lizard...
.
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, swanSwan
Swans, genus Cygnus, are birds of the family Anatidae, which also includes geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe Cygnini. Sometimes, they are considered a distinct subfamily, Cygninae...
s, and bustard
Bustard
Bustards, including floricans and korhaans, are large terrestrial birds mainly associated with dry open country and steppes in the Old World...
s represent the size limit for flying birds. The wing loading of Argentavis was relatively low for its size, a bit more than a turkey
Turkey (bird)
A turkey is a large bird in the genus Meleagris. One species, Meleagris gallopavo, commonly known as the Wild Turkey, is native to the forests of North America. The domestic turkey is a descendant of this species...
's (Campbell & Tonni, 1983), and if there were any significant wind present, the bird could probably get airborne merely by spreading its wings, just like modern albatross
Albatross
Albatrosses, of the biological family Diomedeidae, are large seabirds allied to the procellariids, storm-petrels and diving-petrels in the order Procellariiformes . They range widely in the Southern Ocean and the North Pacific...
es. South America during the Miocene probably featured strong and steady westerly winds, as the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
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
Index finger
The index finger, , is the first finger and the second digit of a human hand. It is located between the first and third digits, between the thumb and the middle finger...
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.
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
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...
s and other actively predatory birds than those of vultures. Most likely teratorns swallowed their prey whole; Argentavis could technically swallow up to hare
Hare
Hares and jackrabbits are leporids belonging to the genus Lepus. Hares less than one year old are called leverets. Four species commonly known as types of hare are classified outside of Lepus: the hispid hare , and three species known as red rock hares .Hares are very fast-moving...
-sized animals in a single piece. Although they undoubtedly engaged in opportunistic scavenging
Scavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
, they seem to have been active predator
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...
s most of the time (Campbell & Tonni, 1983). Teratorns had relatively longer and stouter legs than Old World vultures; thus it seems possible that teratorns would stalk their prey on the ground, 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
Vulture
Vulture is the name given to two groups of convergently evolved scavenging birds, the New World Vultures including the well-known Californian and Andean Condors, and the Old World Vultures including the birds which are seen scavenging on carcasses of dead animals on African plains...
s.
As in other large birds, a clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
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 a dozen in Argentavis (Palqvist & Vizcaíno, 2003).