Cassowaries are a genus of large, flightless birds native to New Guinea, as well as northeastern Australia and some of the Maluku Islands. Though the species vary somewhat in appearance, all of them have black plumage, with a long neck, and a naked, blue-skinned head with a bony casque. Cassowaries vary in size by species but generally average at four to six feet in height.
Cassowary species can be told apart by their colourful heads, necks, and wattles. Northern cassowaries have a blue head, with an orange neck, and blue on the sides. Whereas, southern cassowaries have a blue head and neck with red on their nape and wattles. Finally, dwarf cassowaries have an all-blue head and neck, sometimes with red marks on the sides.
There are three known extant species of cassowary, but one unknown species has been described. British banker, politician, and zoologist Lord Walter Rothschild is notable for describing more than 142 taxa of insects, birds, and reptiles, some of which have never been observed since. One of these is Sclater's cassowary (Casuarius philipi), known from only one specimen that was caught in the wild in eastern German New Guinea (now northeastern Papua New Guinea), and lived in the London Zoo. Rothschild named the species after Dr. Philip L. Sclater, a British zoologist.
Luckily, he described the species in detail in his monograph. The specimen was highly unusual, being only around four feet in height, but extremely bulky, enough that Rothschild compared it to a heavy-footed moa. It also had an unusual horn or casque, being compressed laterally and depressed posteriorly and having a whitish-brown colour. Like other cassowaries, it had all-black plumage, but they were very long and curled, with some of the feathers on its rump nearly touching the ground. Sclater's cassowary had a unique pattern on its head and neck, distinct from any known species. The upper and fore-neck was a dark blue, the nape a bluish-green, the lower hind-neck being yellow, and the lower neck was dark red. Its call was also unique, being described as a "loud, deep roar."
Sclater's cassowary is not currently a recognized species, being dismissed as a freak-specimen or a hybrid. This, however, does not explain its many features that are much too different to simply be a hybrid or deformed animal.