Cassowary - Taxonomy and Evolution

Taxonomy and Evolution

Cassowaries (from the Malay name kasuari) are part of the ratite group, which also includes the Emu, rheas, ostriches, and kiwis, and the extinct moas and elephant birds. There are three extant species recognized today and one extinct:

• Casuarius casuarius, Southern Cassowary or Double-wattled Cassowary, found in southern New Guinea, northeastern Australia, and the Aru Islands, mainly in lowlands.
• Casuarius bennetti, Dwarf Cassowary or Bennett's Cassowary, found in New Guinea, New Britain, and Yapen, mainly in highlands.
• Casuarius unappendiculatus, Northern Cassowary or Single-wattled Cassowary, found in the northern and western New Guinea, and Yapen, mainly in lowlands.
• Casuarius lydekki Extinct

Presently, most authorities consider the above monotypic, but several subspecies have been described of each (some have even been suggested as separate species, e.g., C. (b) papuanus). It has proven very difficult to confirm the validity of these due to individual variations, age-related variations, the relatively few available specimens (and the bright skin of the head and neck—the basis of which several subspecies have been described—fades in specimens), and that locals are known to have traded live cassowaries for thousands, of years, some of which are likely to have escaped or deliberately introduced to regions away from their origin.

The evolutionary history of cassowaries, as of all ratites, is not well known. A fossil species was reported from Australia, but for reasons of biogeography this assignment is not certain and it might belong to the prehistoric Emuarius, which were cassowary-like primitive emus.