Crax
Encyclopedia
Crax is a genus
of curassow
s from tropical South America
. Only the Great Curassow
ranges north through Central America
as far as Mexico
.
The variety of male bill ornament shapes and colors is typical for this genus, as is a curly crest and a contrasting white or rufous crissum. Crax species, even distantly related one, readily hybridize, with fertile offspring theoretically possible in all possible mating combinations
Species are:
This genus forms one of the two major lineages of curassows. It is distinguishable from its relatives by its obvious sexual dimorphism
(only exception being the Black Curassow), which is by size only in Mitu
, and minor or rare in Nothocrax and Pauxi
.
Crax curassows probably originated as a distinct lineage during the Tortonian
(Late Miocene
), some 10-9 mya, in the western or northwestern Amazonas
basin
, as indicated by mt and nDNA sequence
data calibrated against geological events (Pereira & Baker 2004, Pereira et al. 2002). Some 6 mya during the Messinian
, the ancestral Crax split into two lineages which are separated by the Colombia
n Andes
and the Cordillera de Mérida
which were uplifted around that time, and the Orinoco
which consequently assumed its present-day basin.
The northern lineage quite soon thereafter radiated into the ancestors of the Great, Blue-billed, and Yellow-knobbed Curassows, which were isolated from each other by the uplift of the northern Cordillera Occidental
, and the Serrania del Perija
, respectively; it is fairly certain that these lineages were well distinct by the end of the Miocene
. (Pereira & Baker 2004)
The evolution of the 4 southern species was somewhat more complex. In the Messinian, about 6-5.5 mya, the ancestors of the Wattled Curassow became isolated in the western Amazonas basin. With increasing arid
ification of southeastern Brazil, the ancestors of the Red-billed Curassow found refuge in the mountain ranges between the Brazilian Highlands
and the Atlantic during the mid-Zanclean
, some 4.5-4 mya. The divergence between the Bare-faced and Black Curassow lineages apparently took place around the Uquian
-Ensenadan
boundary, some 1.5 mya. This which coincides with one or several period(s) of elevated sea level
s during which the lower Amazonas basin was a brackish lagoon which offered little curassow habitat. Their present ranges are consequently still separated by the Amazonas river. (Pereira & Baker 2004)
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of curassow
Curassow
Curassows are one of the three major groups of cracid birds. Three of the four genera are restricted to tropical South America; a single species of Crax ranges north to Mexico...
s from tropical South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. Only the Great Curassow
Great Curassow
The Great Curassow is a large, pheasant-like bird from the Neotropics. At in length and in weight, this is a very large cracid. No other cracid match its maximum weight, but its length is matched by a few other cracids....
ranges north through Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
as far as Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
.
The variety of male bill ornament shapes and colors is typical for this genus, as is a curly crest and a contrasting white or rufous crissum. Crax species, even distantly related one, readily hybridize, with fertile offspring theoretically possible in all possible mating combinations
Species are:
- Great CurassowGreat CurassowThe Great Curassow is a large, pheasant-like bird from the Neotropics. At in length and in weight, this is a very large cracid. No other cracid match its maximum weight, but its length is matched by a few other cracids....
, Crax rubra - Blue-billed CurassowBlue-billed CurassowThe Blue-knobbed Curassow or Blue-billed Curassow is a species of bird in the Cracidae family, which includes the chachalacas, guans, and curassows....
, Crax alberti - Yellow-knobbed CurassowYellow-knobbed CurassowThe Yellow-knobbed Curassow is a large species of bird found in forest and woodland in Colombia and Venezuela. It feeds mainly on the ground, but flies up into trees if threatened. Its most striking features are its crest, made of feathers that curl forward, and the fleshy yellow knob at the base...
, Crax daubentoni - Wattled CurassowWattled CurassowThe Wattled Curassow is a threatened member of the family Cracidae, the curassows, guans, and chachalacas. It is found in remote rainforests in the western Amazon Basin in South America.-Description:...
, Crax globulosa - Red-billed CurassowRed-billed CurassowThe Red-knobbed Curassow or Red-billed Curassow, Crax blumenbachii, is an endangered species of Cracid that is endemic to lowland Atlantic Forest in the states of Espírito Santo, Bahia and Minas Gerais in southeastern Brazil. Its population is decreasing due to hunting and deforestation, and it has...
Crax blumenbachii - Bare-faced CurassowBare-faced CurassowThe Bare-faced Curassow is a species of bird in the Cracidae family, the chachalacas, guans, curassows, etc.It is found in eastern-central and southern Brazil, Paraguay, and eastern Bolivia, and extreme northeast Argentina, in the cerrado, pantanal, and the southeastern region of the Amazon...
, Crax fasciolata - Black CurassowBlack CurassowThe Black Curassow , also known as the Smooth-billed Curassow, and the Crested Curassow, is a species of bird in the Cracidae family, the chachalacas, guans, and curassows. It is found in humid forests in northern South America in Colombia, Venezuela, the Guianas and far northern Brazil...
, Crax alector
This genus forms one of the two major lineages of curassows. It is distinguishable from its relatives by its obvious sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
(only exception being the Black Curassow), which is by size only in Mitu
Mitu (bird)
Mitu is a genus of curassows, large birds in the family Cracidae. They are found in humid tropical forests in South America. Their plumage is iridescent black with a white or rufous crissum and tail-tip, and their legs and bills are red...
, and minor or rare in Nothocrax and Pauxi
Pauxi
The genus Pauxi consist of the two species of helmeted curassows, terrestrial black fowl with ornamental casque on their heads. Both are found in South America.This genus contains only 2 species, namely...
.
Crax curassows probably originated as a distinct lineage during the Tortonian
Tortonian
The Tortonian is in the geologic timescale an age or stage of the late Miocene that spans the time between 11.608 ± 0.005 Ma and 7.246 ± 0.005 Ma . It follows the Serravallian and is followed by the Messinian....
(Late 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...
), some 10-9 mya, in the western or northwestern Amazonas
Amazon Basin
The Amazon Basin is the part of South America drained by the Amazon River and its tributaries that drains an area of about , or roughly 40 percent of South America. The basin is located in the countries of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, and Venezuela...
basin
Depression (geology)
A depression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms.Structural or tectonic related:...
, as indicated by mt and nDNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data calibrated against geological events (Pereira & Baker 2004, Pereira et al. 2002). Some 6 mya during the Messinian
Messinian
The Messinian is in the geologic timescale the last age or uppermost stage of the Miocene. It spans the time between 7.246 ± 0.005 Ma and 5.332 ± 0.005 Ma...
, the ancestral Crax split into two lineages which are separated by the Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
n 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...
and the Cordillera de Mérida
Cordillera de Mérida
The Cordillera de Mérida is a series of mountain ranges, or massif, in northwestern Venezuela. The Cordillera de Mérida is a northeastern extension of the Andes Mountains. The ranges run southwest–northeast between the Venezuelan–Colombian border and the Venezuelan coastal range...
which were uplifted around that time, and the Orinoco
Orinoco
The Orinoco is one of the longest rivers in South America at . Its drainage basin, sometimes called the Orinoquia, covers , with 76.3% of it in Venezuela and the remainder in Colombia...
which consequently assumed its present-day basin.
The northern lineage quite soon thereafter radiated into the ancestors of the Great, Blue-billed, and Yellow-knobbed Curassows, which were isolated from each other by the uplift of the northern Cordillera Occidental
Cordillera Occidental, Colombia
The Cordillera Occidental is one of three branches of the Andes Mountains in Colombia that divide at the Node of Pasto, extending from south to north from Nariño to the Node of Paramillo in Córdoba....
, and the Serrania del Perija
Serrania del Perija
The Serranía del Perijá, Cordillera de Perijá or Sierra de Perijá is a mountain range, an extension of the eastern Andean branch , in northern South America, between Colombia and Venezuela, ending further north in the Guajira Desert, a total distance of about 310 km...
, respectively; it is fairly certain that these lineages were well distinct by the end of the 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...
. (Pereira & Baker 2004)
The evolution of the 4 southern species was somewhat more complex. In the Messinian, about 6-5.5 mya, the ancestors of the Wattled Curassow became isolated in the western Amazonas basin. With increasing arid
Arid
A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...
ification of southeastern Brazil, the ancestors of the Red-billed Curassow found refuge in the mountain ranges between the Brazilian Highlands
Brazilian Highlands
The Brazilian Highlands or Brazilian Plateau are an extensive geographical region, covering most of the eastern, southern and central portions of Brazil, in all approximately half of the country's land area, or some 4,500,000 km²...
and the Atlantic during the mid-Zanclean
Zanclean
The Zanclean is the lowest stage or earliest age on the geologic time scale of the Pliocene. It spans the time between 5.332 and 3.6 Ma ± 0.005 Ma . It is preceded by the Messinian age of the Miocene epoch, and followed by the Piacenzian age....
, some 4.5-4 mya. The divergence between the Bare-faced and Black Curassow lineages apparently took place around the Uquian
Uquian
The Uquian age is a period of geologic time within the Pliocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Montehermosan and precedes the Ensenadan age....
-Ensenadan
Ensenadan
The Ensenadan age is a period of geologic time within the Early Pleistocene epoch of the Neogene used more specifically with South American Land Mammal Ages. It follows the Uquian and precedes the Lujanian age....
boundary, some 1.5 mya. This which coincides with one or several period(s) of elevated sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
s during which the lower Amazonas basin was a brackish lagoon which offered little curassow habitat. Their present ranges are consequently still separated by the Amazonas river. (Pereira & Baker 2004)