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''Teratornis'' (Greek: "wonder" (teretos), "bird" (ornis)) was a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of huge
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
n
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 ...
– the best-known of the
teratorns Teratornithidae is an extinct family (biology), family of very large Bird of prey, birds of prey that lived in North and South America from the Oligocene, Late Oligocene to the Pleistocene, Late Pleistocene. They include some of the largest known ...
- of which, two species are known to have existed: ''Teratornis merriami'' and ''Teratornis woodburnensis''. A large number of
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
and
subfossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
bones, representing more than 100 individuals, have been found in locations in
California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
,
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
, southern
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
,
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
, and
Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...
, though most are from the Californian
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 ...
. All remains except one
Early Pleistocene The Early Pleistocene is an unofficial sub-epoch in the international geologic timescale in chronostratigraphy, being the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently estimated to span the time ...
partial skeleton from the Leisey Shell Pit near
Charlotte Harbor, Florida Charlotte Harbor is a census-designated place (CDP) in Charlotte County, Florida, United States. The name Charlotte Harbor also refers to Charlotte Harbor (estuary) and Charlotte Harbor Preserve State Park, a preserve with of shoreline along ...
(which may represent a different species or a subspecies) date from 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 ...
, with the youngest remains dating from the
Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
-
Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...
boundary.


Taxonomy

* ''Teratornis merriami''. This is by far the best-known species. Over a hundred 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 75 cm (29.5 in) tall with estimated wingspan of perhaps 3.5 to 3.8 metres (11.5 to 12.5 ft), and its weight has been estimated within the range of 12.5-15.0 kg with 95% confidence; making it about a third bigger than extant condors. It became extinct at the end of the Pleistocene, some 10,000 years ago. Before formation of the Teratornithidae family, The ''T.merriami's'' hooked beak and skull morphology led to its initial placement in the family Vulturidae alongside New World Vultures. Further analysis has suggested a potentially equal relation to storks in the Ciconiidae family. Despite similarities, these three families can be differentiated by their differing skulls in response to significantly different feeding methods. * ''Teratornis woodburnensis''.Campbell, Kenneth E. Jr. & Stenger, Allison T. (2002)
A New Teratorn (Aves: Teratornithidae) from the Upper Pleistocene of Oregon, USA
. pp. 1–11. in Zhou, Z. and F. Zhang. ''Proceedings of the 5th Symposium of the Society of Avian Paleontology and Evolution Beijing'', 1–4 June 2000. China Science Press, Beijing.
The first species to be found north of the La Brea Tar Pits, this partial specimen was discovered at Legion Park, Woodburn, Oregon in 1999. 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, about 12,000 years ago, in a stratum containing the remains of
megafauna In terrestrial zoology, the megafauna (from Greek μέγας ''megas'' "large" and New Latin ''fauna'' "animal life") comprises the large or giant animals of an area, habitat, or geological period, extinct and/or extant. The most common threshold ...
such as mammoth, mastodon, and ground sloths, as well as evidence of early human occupancy at the site. 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, but has also been placed in its own genus, ''Oscaravis''. 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 ...
, but apart from these forms, teratorns were restricted to North America. A closely related genus, ''
Aiolornis ''Aiolornis incredibilis'' is an extinct species of teratorn bird from the western United States. Only fragmentary remains have been found, which are dated between the Early Pliocene (Zanclean) and Late Pleistocene. First described as ''Teratorni ...
'', 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.


Description

According to description of 1945, ''Teratornis merriami'' had a wingspan of around and a wing area of 17.5 square meters, standing an estimated tall. It was somewhat larger than the extant
Andean condor The Andean condor (''Vultur gryphus'') is a giant South American Cathartid vulture and is the only member of the genus ''Vultur''. Found in the Andes mountains and adjacent Pacific coasts of western South America, the Andean condor is the larg ...
, and by calculating the area of the organism's sternum and synsacrum, ''Teratornis'' was estimated to weigh about , which was nearly double the weight of an average Californian condor. A 1983 study gives a range of wingspan of and a weight of . The finger bones of the Teratornis were 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 Primary elections, or direct primary are a voting process by which voters can indicate their preference for their party's candidate, or a candidate in general, in an upcoming general election, local election, or by-election. Depending on the c ...
, enabling the bird to utilize strong upcurrents in flight. Their legs were similar to an Andean condor's, but stouter, and the feet could hold prey for tearing off pieces, but could not exert a very forceful grip like birds of prey. Its
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 ...
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. Indeed, it seems to have been better adapted 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. Thus, ''Teratornis'' may have primarily inhabited cliff terrain, where it could take off and soar through the air easily.


Paleobiology


Diet and Feeding Habits

The ''T. merriami'' was similar to
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 ...
s, although an analysis of the functional
morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
of its skull, namely its larger bill and ability to spread its mandibles and swallow its prey whole, suggests that it was an active and carnivorous predator rather than a scavenger. In fact, some studies of skull morphology indicated that the ''T.merriami'' were incapable of tearing pieces of flesh off of carcasses in the manner of condors. Alternative viewpoints note that 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, Kite (bird), kites, and hawks. Old World vultures ...
possess large bills, and a longer bill is a common feature among scavenging raptors, as this allow them to probe deeper into large carcasses - larger than those fed upon by active-hunting raptors. Other anatomical features, such as the relatively small and sideward facing orbits and the low skull, are also consistent with a scavenging lifestyle. For the ''T.merriami'', small prey such as frogs, lizards, young birds, and rodents were swallowed whole, while
carrion Carrion () is the decaying flesh of dead animals, including human flesh. Overview Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures, c ...
would have been fed on in a manner similar to that of condors or
vultures 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 So ...
.


Locomotion

An analysis of the Teratorn pelvic girdle and stout, columnar hind leg bones suggests that its legs had greater anteroposterior ability than those of condors, and that the birds were agile and well-suited for walking and stalking prey on the ground similarly to storks and turkeys. On the other hand, their flight was similar to that of condors. Condors fly by means of soaring on rising up-currents, generally weak currents that are subject to sudden changes in direction or strength. Their ability to react to these changes and maintain flight has to do with their emarginated
primary feathers Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail ...
which separate and move independently during flight, contrary to the unemarginated primary feathers of birds who dynamically soar on more reliable air currents.


Habitat

''Teratornis'' had legs that were too short for it to take flight by running on flat ground. It is theorized that the Teratornis primarily inhabited cliff terrain, where it could take off and soar through the air easily. Many Teratorn bone samples contributing to modern research have been found at 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 ...
in Los Angeles, California. Teratorns are thought to have been attracted by
Pleistocene megafauna Pleistocene megafauna is the set of large animals that lived on Earth during the Pleistocene epoch. Pleistocene megafauna became extinct during the Quaternary extinction event resulting in substantial changes to ecosystems globally. The role of hu ...
that became stuck and died in the viscous
asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
while trying to drink from pools of water that gathered on the surface, with the teratorns subsequently falling victim to the sticky deposits. Merriam's Teratorn probably played an important role in opening up the body cavities of carcasses for smaller birds like
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
raven A raven is any of several larger-bodied bird species of the genus ''Corvus''. These species do not form a single taxonomic group within the genus. There is no consistent distinction between "crows" and "ravens", common names which are assigned t ...
s which are also known to have frequented the locality, as
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
ian predators-- being unable to fly-- could hardly reach most carcasses without getting mired in the asphalt themselves. However, there were also true
vultures 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 So ...
present in the area at that time, and unlike those, ''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 The osprey (''Pandion haliaetus''), , also called sea hawk, river hawk, and fish hawk, is a diurnal, fish-eating bird of prey with a cosmopolitan range. It is a large raptor reaching more than in length and across the wings. It is brown o ...
, which also provides a reasonable explanation of how such large numbers of powerful, well-flying birds could have become stuck in the asphalt.


References

{{Taxonbar, from=Q137294 Bird genera Late Quaternary prehistoric birds Pleistocene birds Teratornithidae Extinct animals of the United States Pleistocene genus extinctions Pleistocene birds of North America Fossil taxa described in 1909 Taxa named by Loye H. Miller