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18.12.2015 21:35 - Encyclopedia Largest prehistoric animals Vol.1 Vertebrates part2 Birds ch.5 Teratorns,Hawks and Eagles
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Teratorns are an extinct group of giant predatory birds that are classified in the bird family Teratornithidae.The name “teratorn” means “Wonder Bird,” a name given because of the size, uniqueness, and powerful nature of this group of birds. The first species of teratorn known, Teratornis merriami, was described from the late Pleistocene Rancho La Brea tar pits of Southern California, where the remains of more than 100 individuals of this species have been found. Merriam’s teratorn weighed about 13–14 kg (about 30 lb.) and had a wingspan of about 3.2 m (10.5 ft.). Two other genera of teratorns have been described from California, and other species have been described from Oregon, Cuba, and South America. 
The largest known flying bird, Argentavis magnificens, is a teratorn that lived about six million years ago in Argentina. This teratorn had a wingspan of 6.5–7.5 m (21–24 ft.), weighed about 72–78 kg (158–172 lb.), and had flight feathers that would have been about 150 cm (59 in.) long.

Teratorns were predatory birds that probably captured small animals, such as lizards, mice, and other birds, and swallowed them whole. We can tell this from the structure of their jaw bones, which is quite different from those bones found in New World vultures (such as the California Condor) or raptors (such as hawks and owls).Teratorns definitely did not feed on the carcasses of large mammals, as is so often portrayed in older literature.
Teratorns had very short legs and broad bodies, so they could not have run very fast. Although they might have captured prey in flight by swooping close to the ground and using their long bill, it is more likely that they were stalkers that moved very slowly while hunting on the ground. They might also have remained motionless, in which case prey would come within striking distance and be seized by the teratorns using their long, hooked bill. Stalking small animals that were struggling to free themselves from the tar seeps at Rancho La Brea would have brought teratorns into situations where they would have become stuck themselves.The wing bones of teratorns are typical of those of large soaring birds, so their flight behavior would have been similar to that of vultures and large storks. Soaring is a very easy way for large birds to cover large distances in search of food. Teratorns must have inhabited areas with relatively few trees or large shrubs because their large wings would have made maneuvering in forests impossible. The biggest teratorns are all known from semiarid regions.

Aiolornis incredibilis (formerly Teratornis incredibilis), of the teratorn family, was the largest known North American flight-capable bird, with a wingspan of up to approximately 5 m (16 ft) and a huge, deep, powerful bill. The typical body mass of this bird was estimated to be 23 kg (51 lb), significantly heavier than any extant flying bird.A. incredibilis presumably became extinct at the same time as the other megafauna in North America. It is sometimes called the giant condor because of its resemblance to the modern condors of California and South America, although it is bigger and in a different family. It is not well known but is quite similar to Teratornis merriami, although about 40% larger overall. Fossils have been found from the Early Pliocene to the Late Pleistocene in various locales in the southwestern and western-central part of the USA; it is not certain that all belong to the same species given the large time range and the lack of complete specimens.

Teratornis was a huge North American teratorn bird of prey. It is the best-known of the teratorns. A large number of fossil and subfossil bones, representing more than 100 individuals, have been found in locations in California, Oregon, southern Nevada, Arizona, and Florida, though most are from the Californian La Brea Tar Pits. All remains except one Early Pleistocene partial skeleton from the Leisey Shell Pit near Charlotte Harbor, Florida (which may represent a different species or a subspecies) date from the Late Pleistocene, with the youngest remains dating from the Pleistocene-Holocene boundary.
Teratornis merriami.This is by far the best-known species. Over a hundred specimens have been found, mostly from La Brea Tar Pits. 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 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 4 meters (14 ft). The find dates to the late Pleistocene, between 11,000 and 12,000 years ago, in a strata which is filled with the bones of Mastodon, Sloth and Condors, and bears evidence of human habitation.
Another form, "Teratornis" olsoni, was described from the Pleistocene of Cuba, but its affinities are not completely resolved; it might not be a teratorn, but has also been placed in its own genus, Oscaravis. There are also undescribed fossils from southwestern Ecuador, but apart from these forms, teratorns were restricted to North America.
Teratornis merriami had a wingspan of around 3.5 to 3.8 m (11 to 12 ft) and a wing area of 17.5 square meters, standing an estimated 75 cm (30 in) tall. It was somewhat larger than the extant Andean Condor and weighing about 15 kg (33 lb), was nearly double the weight of an average California Condor. A closely related genus, Aiolornis, was about 40% larger and lived at an earlier time; it was formerly known as Teratornis incredibilis, but is distinct enough to be placed in its own genus.
The finger bones are fused as in all modern birds; however, part of the index finger forms a shelf which aided in bearing the load of long and stout primaries, which enabled the bird to utilize strong upcurrents. The legs were similar to an Andean Condor"s, but stouter, and the feet could hold prey items for tearing off pieces, but could not exert a very forceful grip such as in birds of prey. Its wing loading was not much larger than a Californian Condor"s, and Merriam"s Teratorn should have been able to take off by simply jumping and beating its wings under most circumstances.ndeed, it seems to have been better adapted for that than for utilizing a short run into the wind from an elevated location as condors do, as its legs are proportionally smaller and its stride less than in condors.
T. merriami generally lived in a manner similar to condors, although its larger bill suggests that it was a more active predator. Prey up to the size of a small rabbit would probably have been swallowed more or less whole, while carrion would have been fed on in a manner similar to that of condors or vultures. The large number of finds in the La Brea Tar Pits were usually considered to be from teratorns which were attracted by Pleistocene megafauna that became stuck and died in the viscous asphalt while trying to drink from pools of water that gathered on the surface, with the teratorns subsequently falling victim to the sticky deposits too. Merriam"s Teratorn probably played an important role in opening up the body cavities of carcasses for smaller birds like eagles and ravens which are also known to have frequented the locality, as mammalian predators, being unable to fly, could hardly reach most carcasses without getting mired in the asphalt themselves.
However, there were also true vultures present in the area at that time, and unlike them, T. merriami was also well adapted to hunt for smaller animals which are also known to have utilized the pools. Analysis of the skull and bill shapes suggests that fish may have constituted a major part of its diet. Taking into account the strong legs, stout claws, and a gripping power not quite as developed as in eagles, it is rather likely that Merriam"s Teratorn would have hunted for aquatic prey in the manner of an osprey, which also provides a neat explanation of how such large numbers of powerful, well-flying birds could have become stuck in the asphalt.
The species probably became extinct as the climatic shifts at the end of the last ice age led to widespread ecological alterations and prey scarcity, exacerbated by human hunting and increasing influence on habitat; generally, most large land animals disappeared and the altered precipitation patterns seriously affected populations of aquatic vertebrates. Despite being a better hunter than the Californian Condor, it still was inferior as a predator of small prey to hawks and eagles. The higher population density and more flexible diet of the condor probably ensured that it survived, while T. merriami did not. Recent isotopic studies suggest that the California Condor survived the extinction of the megafauna because it also scavenged dead marine mammals off the Pacific Coast. The teratorn relied more heavily on the carrion of land mammals and therefore could not survive their extinction.

Accipitriformes are a linage of birds that include most of the world"s diurnal raptors, the sole exception being falcons; while both Accipitriformes and Falconiformes belong to the same linage within Neornithes (the derived "Land Birds" clade), they are as "far apart" within such clade as possible. Avian evolution is a troubled matter, but understanding of genetic relationships between modern birds allowed a more precise analysis on the evolution of several bird clades. Accipitriformes is perhaps one of the most easy to interpret the evidence accurately.
Based on the most recent genetic evidence, Accipitriformes is part of a clade of derived Neornithes known colloquially as "Land Birds"; this particular clade is divided into two main linages, one concerning falcons, seriemas, parrots and passerines, and the other Accipitriformes, mousebirds, trogons, owls and Coraciiformes (Piciformes being within the later). The "Land Birds" appear to be a clade based on Gondwanna; the group that includes falcons and their close relatives seems to have originated in "main Gondwannaland", which in the late Cretaceous was composed of South America, Madagascar, Antartica and Australia, whereas Accipitriformes and their closest relatives appear to have evolved in Africa, then a gigantic island continent. For reasons of convenience, thus, we will term falcons, parrots, seriemas and passerines as "Antartic Land Birds", and Accipitriformes, owls, mousebirds, trogons as Coraciiformes as "African Land Birds".
Within the African Land Birds, Accipitriformes seems to be the most basal, followed closely by a single clade composed of owls and mousebirds. Because of the stravagant variety of forms within the African Land Birds, it is very hard to speculate accurately on how was the common ancestor of this clade, although it is logical to think that it was a relatively small shorebird/tinamou/dove like form, since it seems to be the default forms of basalmost neornithes. It is, however, now relatively easy to speculate on how the ancestral Accipitriformes were like; the basalmost accipitrids (the main linage within Accipitriformes, which includes hawks, Old World vultures, kites and eagles) are appearently gypaetine vultures - Old World vultures are not a monophyletic group, but a polyphyletic one, composed of two linages, the other one being the aegypitine vultures, which are essencially "bald" eagles -, a group composed of the Lammergeier, the Hooded Vulture and the Egyptian Vulture, and these vultures are very similar in appearence to the basalmost clade within Accipitriformes, Cathartidae or "New World Vultures". Therefore, the earliest Accipitriformes were most likely scavenging birds akin to gypaetine or cathartid vultures, which evolved in Africa during the very beginning of the Cenozoic.
The divergence between the main Accipitriforme clades occured very early, and it is safe to say that, by the Middle of the Eocene, Cathartidae, Sagittaridae, Pandionidae (but see below) and Accipitridae were already distinct. New World vultures crossed the Atlantic and arrived into South America, being probably the first participants of an incredible vertebrate migration from Africa to South America (later participants being rodents, primates and tortoises, among others). There, in direct competion with the early falcons, they kept their scavenging niches and changed relatively little across the Cenozoic, until the Miocene where we see the arrival of the giant teratorns, which became large aerial predators, similar perhaps to the accipitrid eagles, but reaching much larger sizes. Also, unlike other Accipitriformes, cathartids never developed strong talons and grasping hallux, so these giant winged predators most likely used their beaks; modern cathartids, while generally scavengers, occasionally can kill prey, and always they do so with their beaks. In turn, without being specialised to kill prey, the feet are perfect for running, and thus allow these birds more efficient terrestrial locomotion than other Accipitriformes. This may explain why they so efficiently replaced accipitrid vultures in the Americas (see below).
Soon after the cathartids diverged, so did the linage that produced the modern Secretary Bird. Little is known about fossil species; the most notable ones are the two species of the genus Pelargopappus, one from the Oligocene and another from the Eocene, both from France. It seems, these birds weren"t direct ancestors of the secretary bird; both belong to a linage of birds that evolved to fill a similar niche to the accipitrid hawks and some falcons, having grasping talons to catch prey. The modern species, on the other hand, is terrestrial and cursorial, and thus it is more likely it evolved from an unspecialised early vulture like form than from a more derived hawk like one. The large flightless bird from the Eocene known as Eremopezus has been suggested as being an early relative of the secretary bird; if so, it was remarkably specialised for its time. For obvious reasons, not everyone agrees with this interpretation, and in truth it is likely we"ll never know the true affinities of that enigmatic bird.
The Osprey is usually placed as seperate from Accipitridae, as the last linage within Accipitriformes to diverge before this clade. However, this is highly controversial, and there is virtually no fossil record of Pandionidae besides the titular species itself. Based on its anatomy, it is more safe to say that it is within the Oligocene/Miocene radiation of accipitrids and thus a very derived Accipitriforme than member of a ghost linage that dates back to the Eocene and beyond. No genetic comparation between the Osprey and the rest of Accipitridae has been made, ence this is currently unknown.
And thus it comes Accipitridae itself. Very early did these birds expanded beyond their home continent and conquered the vast majority of the main bird of prey niches in the world, leaving room only for the falcons, owls and cathartids; for a while, it seems that sagittarids managed to compete with them, as shown before, until they were eventually completly replaced sans for their current single species. Relationships within this clade are not always very clear, but it is general consensus that the most basal members are gypaetine vultures, followed by kites and sea eagles, and the rest belong to a central accipitrid linage that encompasses the rest. The very first accipitrid fossils come from the Eocene of Europe, and as early as the early Oligocene they occured in Australia; said continent seems to have had an endemic branch of native accipitrids, of which numerous forms are known, but are all poorly known except for Pengana, a bizarre bird with extra-flexible ankles, an adaptation to reach deeper within holes and crevices in search of prey. These australian raptors were soon replaced by invading accipitrids from Asia.
Through the Oligocene and Miocene, Old World vultures, both gypaetine and aegypitine, were the dominant scavengers across the northern hemisphere, occuring even in North America. Only in the late Miocene did invading cathartids replaced these accipitrids, being the first of a wave of invaders from the south. Their better adaptations for cursoriality seemed to have favoured them over the accipitrids, and for once did the main linage of Accipitriformes lost while competing with another clade.

The largest proper bird of prey ever was the enormous Haast"s eagle (Harpagornis moorei), with a wingspan of 2.6 to 3 m (8.5 to 9.8 ft), relatively short for their size. Total length was probably up to 1.4 m (4.6 ft) in female and they weighed about 10 to 15 kg (22 to 33 Ib).
Haast"s eagle was first described by Julius von Haast in 1871 from remains discovered by F. Fuller in a former marsh.Haast named the eagle Harpagornis moorei after George Henry Moore, the owner of the Glenmark Estate, where the bones of the bird had been found.The genus name is from the Greek "harpax", meaning "grappling hook", and "ornis", meaning "bird".
DNA analysis has shown that this raptor is related most closely to the much smaller little eagle as well as the booted eagle and not, as previously thought, to the large wedge-tailed eagle. Thus, Harpagornis moorei may eventually be reclassified as Hieraaetus moorei. H. moorei is estimated to have diverged from these smaller eagles as recently as 1.8 million to 700,000 years ago. If this estimate is correct, its increase in weight by ten to fifteen times is an exceptional evolutionary increase in weight of any known vertebrate. This was made possible in part by the presence of large prey and the absence of competition from other large predators.
Haast"s eagles were one of the largest known true raptors. In length and weight, Haast"s eagle was even larger than the largest living vultures. Another giant eagle from the fossil record rivaled the Haast"s in at least the aspect of total length, Amplibuteo woodwardi, although other estimations are not known of this more recently and scantly-described species. Female eagles were significantly larger than males. Most estimates place the female Haast eagles in the range of 10–15 kg (22–33 lb) and males around 9–12 kg (20–26 lb).A comparison to living eagles of the Australasian region resulted in estimated masses in Haast"s eagles of 11.5 kg (25 lb) for males and 14 kg (31 lb) for females. One source estimates that the largest females could have scaled more than 16.5 kg (36 lb) in mass.However, even the largest extant eagles, none of which are verified to exceed 9 kg (20 lb) in a wild state, are about forty percent smaller in body size than Haast"s eagles.
They had a relatively short wingspan for their size. It is estimated that the grown female typically spanned up to 2.6 m (8.5 ft), possibly up to 3 m (9.8 ft) in a few cases.This wingspan is broadly similar to the larger range of female size in some extant eagles: the wedge-tailed eagles (Aquila audax), golden eagles (A. chrysaetos), steppe eagles (A. nipalensis), martial eagles (Polemaetus bellicosus) and Steller"s sea eagles (Haliaeetus pelagicus).Several of the largest extant Old World vultures, if not in mean mass or other linear measurements, probably exceeded Haast"s eagle in average wingspan.
Short wings may have aided Haast"s eagles when hunting in the dense scrubland and forests of New Zealand. Haast"s eagle has sometimes been portrayed incorrectly as having evolved toward flightlessness, but this is not so; rather it represents a departure from the mode of its ancestors" soaring flight, toward higher wing loading and the species probably had very broad wings.
While most bones studied have been internal ones, some remains of Haast"s eagles allow people to make comparisons to living eagles. The harpy eagle (Harpia harpyja) and the Philippine eagle (Pithecophaga jefferyi), which are the largest and most powerful living eagles alongside the Steller"s sea eagle, also have similarly reduced relative wing-length in adaptation to forest-dwelling.A lower mandible from the Haast"s eagle measured 11.4 cm (4.5 in) and the tarsus in several Haast"s fossils has been measured from 22.7 to 24.9 cm (8.9 to 9.8 in).In comparison, the largest beaks of eagles today (from the Philippine and the Steller"s sea eagle) reach a little more than 7 cm (2.8 in); and the longest tarsal measurements (from the Philippine and the Papuan eagle) top out around 14 cm (5.5 in).The talons of the Haast"s eagle were similar in length those of the harpy eagle, with a front-left talon length of 4.9 to 6.15 cm (1.93 to 2.42 in) and a hallux-claw of possibly up to 11 cm (4.3 in).The Philippine eagle might make for particularly apt living species to compare the Haast"s eagle with, because it too evolved in an insular environment from smaller ancestors (apparently basal snake eagles) to island gigantism in the absence of large carnivorous mammals and other competing predators.The strong legs and massive flight muscles of these eagles would have enabled the birds to take off with a jumping start from the ground, despite their great weight. The tail was almost certainly long, in excess of 50 cm (20 inches) in female specimens, and very broad. This characteristic would compensate for the reduction in wing area by providing additional lift.Total length is estimated to have been up to 1.4 m (4 ft 7 in) in females, with a standing height of approximately 90 cm (2 ft 11 in) tall or perhaps slightly greater.
Haast"s eagles preyed on large, flightless bird species, including the moa, which was up to fifteen times the weight of the eagle.It is estimated to have attacked at speeds up to 80 km/h (50 mph),often seizing its prey"s pelvis with the talons of one foot and killing with a blow to the head or neck with the other.Its size and weight indicate a bodily striking force equivalent to a cinder block falling from the top of an eight-story building. Its large beak also could be used to rip into the internal organs of its prey and death then would have been caused by blood loss.In the absence of other large predators or scavengers, a Haast"s eagle easily could have monopolised a single large kill over a number of days.
Early human settlers in New Zealand (the Māori arrived around the year 1280) preyed heavily on large flightless birds, including all moa species, eventually hunting them to extinction. The loss of its natural prey caused the Haast"s eagle to become extinct as well around 1400,when the last of its natural food sources were depleted.
A noted explorer, Charles Edward Douglas, claims in his journals that he had an encounter with two raptors of immense size in Landsborough River valley (probably during the 1870s), and that he shot and ate them;but they may have been Eyles" harriers.
Until recent human colonisation that introduced rodents and cats, the only mammals found on the islands of New Zealand were three species of bat, one of which recently has become extinct. Free from terrestrial mammalian competition and predatory threat, birds occupied or dominated all major niches in the New Zealand animal ecology because there were no threats to their eggs and chicks by small terrestrial animals. Moa were grazers, functionally similar to deer or cattle in other habitats, and Haast"s eagles were the hunters who filled the same niche as top-niche mammalian predators, such as tigers or lions.
It is believed that these birds are described in many legends of the Māori, under the names Pouakai, Hokioi, or Hakawai. However, it has been ascertained that the "Hakawai" and "Hokioi" legends refer to the Coenocorypha snipe—in particular the extinct South Island subspecies.According to an account given to Sir George Grey, an early governor of New Zealand, Hokioi were huge black-and-white predators with a red crest and yellow-green tinged wingtips. In some Māori legends, Pouakai kill humans, which scientists believe could have been possible if the name relates to the eagle, given the massive size and strength of the bird.Even smaller golden eagles are capable of killing prey as big as sika deer or a bear cub.

Woodward"s eagle (Amplibuteo woodwardi)
The Woodward"s eagle (Amplibuteo woodwardi) is an extinct species of eagle that lived in North America and the Caribbean during the Late Pleistocene. It is one of the largest birds of prey ever found, with an estimated total length 125.6 to 140.2 cm (49.4 to 55.2 in), and considerably larger than any living eagle. The Haast"s eagle reached similar lengths but appears to have been both somewhat more robust and shorter-winged than Woodward"s, as Haast"s was a forest-dwelling species. Woodward"s eagle appeared to have hunted in open habitats, taking primarily small mammals and reptiles.
The Giant Prairie Eagle is the largest of the North American eagles, reaching total body lengths of 4-4.5
feet(49-55 inches) and wingspans of 9-11 feet from tip to tip. Though being of the same size and weight as the Haast’s Eagle(Harpagornis moorei) of New Zealand, this North American species has proportionally longer wings for flight in wide open country, and the Haast’s Eagle is more robust in build than the Giant Prairie Eagle is, enabling the top New Zealand predator for flight in the forests of New Zealand. As with all species of eagle, the females grow to larger size than the males do. Despite the fact that they bear resemblence to and share a number of behavioral traits to the sympatric Golden Eagle(Aquilla chrysaetos), these eagles are actually quite more closely related to hawks than they are to most other species of eagle.

The largest extinct Titanohierax was a giant hawk about 8 kilograms that lived in the Antilles, where it was among the top predators.

Titanohierax gloveralleni is an extinct giant hawk known from fossils found in Cuba, Hispaniola and the Bahamas. Titanohierax was a giant hawk with a measured fore-claw length of 57 mm (2.2 in) and an estimated weight of around 7.3 kg (16 lb), making roughly equal in size to the females of the largest living eagles.This raptor lived in the Antilles, where it was probably an apex predator.

The extinct crab-hawk Buteogallus borrasi was formerly placed in this genus with T. gloveralleni.
T. gloveralleni"s closest living relatives are the modern, still extant species of crab-hawks in Buteogallus.





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