Crax
| Crax | |
|---|---|
 |
|
| Blue-billed curassow, Crax alberti | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Galliformes |
| Family: | Cracidae |
| Genus: |
Crax Linnaeus, 1758 |
| Species | |
|
7, see text. |
|
7, see text.
Crax is a genus of curassows in the order Galliformes, a clade of large, heavy-bodied, ground-feeding birds. They are known from tropical South America with one species, the great curassow, ranging northwards through Central America as far as Mexico. The currasows in this genus are noted for their sexual dimorphism; males are more boldly coloured than females and have facial ornamentation such as knobs and wattles. They are also characterised by curly crests and contrastingly-coloured crissums (the area around the cloaca). Crax curassows probably originated as a distinct lineage during the Late Miocene. During the Messinian, the ancestral Crax split into two lineages separated by the Colombian Andes and the Cordillera de Mérida which uplifted at that time. The northern lineage radiated into the great, blue-billed, and yellow-knobbed curassows, while the four southern species evolved as they became separated by the uplifting of various mountain ranges.
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 Colombian Andes and the Cordillera de Mérida which were uplifted around that time, and the Orinoco which consequently assumed its present-day basin.
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Wikipedia