''Buteogallus borrasi'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of giant buteonine

hawk Hawks are bird of prey, birds of prey of the family Accipitridae. They are widely distributed and are found on all continents except Antarctica. * The subfamily Accipitrinae includes goshawks, sparrowhawks, sharp-shinned hawks and others. Th ...

which went extinct in the early

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 ...

. Formerly

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

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 ...

, this huge

bird 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 h ...

probably fed on

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 ...

. Little is known about its appearance and ecology, so no common name has been given. Because of its eagle-like size, it was originally assigned to ''Aquila borrasi''. In 1982 the new

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''Titanohierax borrasi'' was suggested; ''Aquila borrasi'' was found valid again in 2004. A 2007 study earned it its current classification and found close similarities to the extant

great black hawk The great black hawk (''Buteogallus urubitinga'') is a bird of prey in the family Accipitridae, which also includes the eagles, hawks, and Old World vultures. Taxonomy The great black hawk was Species description, formally described in 1788 by t ...

(''Buteogallus urubitinga'').

Description

The latest scientific research describes ''B. borrasi'' as very similar to its extant relative, the

(''B. urubitinga''). However, it was one third as big again as that bird. Compared to other large birds of prey that shared its habitat—

Woodward's eagle Woodward's eagle (''Buteogallus 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 , slightly ...

, ''

Titanohierax ''Titanohierax gloveralleni'' is an extinct hawk species known from fossils found in Cuba, Hispaniola (today the Dominican Republic and Haiti), and The Bahamas. Description ''Titanohierax'' was a very large hawk, with a measured fore-claw len ...

'' and '' Gigantohierax''—it had relatively gracile features.

History

Oscar Arredondo described ''B. borrasi'' in 1970, based on finds from Western

: an incomplete left

tarsometatarsus The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) and meta ...

(the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

), a fragmentary right

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

and some

phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...

. In 1982

Storrs L. Olson Storrs Lovejoy Olson (April 3, 1944 – January 20, 2021) was an American biologist and ornithologist who spent his career at the Smithsonian Institution, retiring in 2008. One of the world's foremost avian paleontologists, he was best known ...

and William Hilgartner examined the holotype and, finding it dissimilar to '' Aquila'' tarsometatarsi, suggested it be referred to '' Titanohierax gloveralleni''. In 1999, Arredondo realized the femur and one of the phalanges did not belong to ''B. borrasi'', and assigned them to the new species ''

Gigantohierax suarezi ''Gigantohierax'' is a genus of eagle from the Quaternary of present-day Cuba. Little is known about the two known species of the genus other than their very large size. Species and discovery It is known from two species, ''Gigantohierax suarezi ...

''. In 2004, William Suárez concluded that the species was valid but could not be referred to the genus ''Titanohierax''. Meanwhile, a considerable amount of new fossil material was being discovered. Olson and Suárez reassigned the bird to ''Buteogallus'' in 2007. They found the tarsometatarsus and tibiotarsus far too slender and elongate for an ''Aquila'' eagle, but very similar to those of the great black hawk (''B. urubitinga''). Some mismatches were attributed to the size difference between the two species.

Paleoecology

Fossil remains of ''B. borrasi'' are known only from Cuba. However, it has been postulated to have roam the wider

West Indies The West Indies is a subregion of North America, surrounded by the North Atlantic Ocean and the Caribbean Sea that includes 13 independent island countries and 18 dependencies and other territories in three major archipelagos: the Greater A ...

and perhaps even mainland

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 ...

. It is the most common fossil accipitrid in Quaternary deposits of Cuba, notably at Llanura Meridional de La Habana. These deposits are thought to be from a savanna environment. The shape of the tarsus suggests a bird that hunts on the wing, and the mammalian fauna of the time suggests a diet of small- to medium-sized

rodents Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are nat ...

and

insectivora The order Insectivora (from Latin ''insectum'' "insect" and ''vorare'' "to eat") is a now-abandoned biological grouping within the class of mammals. Some species have now been moved out, leaving the remaining ones in the order Eulipotyphla, w ...

, which may have been supplemented with reptiles in open areas. Olson suggests two possible origins for ''B. borrasi'': either it diverged from ''B. urubitinga'' in Cuba, or it evolved on the mainland and eventually became extinct there, leaving a

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

population in Cuba.

In culture

''Buteogallus borrasi'' (under the

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

''Aquila borrasi'') is featured on a 1982 Cuban

postage stamp A postage stamp is a small piece of paper issued by a post office, postal administration, or other authorized vendors to customers who pay postage (the cost involved in moving, insuring, or registering mail), who then affix the stamp to the fa ...

, part of a series on prehistoric animals. However, the illustration—derivative of a work by Arthur B. Singer—actually depicts an

ornate hawk-eagle The ornate hawk-eagle (''Spizaetus ornatus'') is a fairly large bird of prey from the tropical Americas. Formerly, some authorities referred to this species as the crested hawk-eagle, a name that may cause some confusion as it is more commonly us ...

(''Spizaetus ornatus'').

References

Other large fossil accipitrids of the Quaternary in the West Indies: *''

Buteogallus daggetti ''Buteogallus daggetti'', occasionally called "Daggett's eagle" or the "walking eagle", is an extinct species of long-legged hawk which lived in southwest North America during the Pleistocene. Initially believed to be some sort of carrion-eating ...

'' underwent a similar reclassification by Olson in 2007 *''

Amplibuteo woodwardi Woodward's eagle (''Buteogallus 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 , slightly ...

'' *''

'' *'' Gigantohierax'' {{Taxonbar, from=Q5002500 Late Quaternary prehistoric birds Buteogallus Hawks Holocene extinctions Extinct birds of the Caribbean Birds described in 1970 Fossil taxa described in 1970 Extinct animals of Cuba