Here is an abridged description of the black rhinoceros from Wikipedia:
The black rhinoceros or hook-lipped rhinoceros (Diceros bicornis) is a species of rhinoceros, native to eastern and southern Africa. Although the rhinoceros is referred to as black, its colors vary from brown to grey.
The other African rhinoceros is the white rhinoceros (Ceratotherium simum). The word “white” in the name “white rhinoceros” is often said to be a misinterpretation of the Afrikaans word wyd meaning wide, referring to its square upper lip, as opposed to the pointed or hooked lip of the black rhinoceros. These species are now sometimes referred to as the square-lipped (for white) or hook-lipped (for black) rhinoceros.
The species overall is classified as critically endangered, and three subspecies, one including the western black rhinoceros, were declared extinct by the IUCN in 2011.
Both pictures were taken by my wife earlier this month in Namibia, Africa.