Such a skull is known to have existed and Linnaeus even mentioned India as origin of this species. The two species evolved from the common ancestral species Ceratotherium neumayri during this time.
However he also referred to reports from early travellers about a double-horned rhino in Africa and when it emerged that there is only one, single-horned species of rhino in India, "Rhinoceros" bicornis was used to refer to the African rhinos (the white rhino only became recognised in 1812). The clade comprising the genus Diceros is characterised by an increased adaptation to browsing.
Three subspecies have been declared extinct, including the western black rhinoceros, which was declared extinct by the International Union for Conservation of Nature (IUCN) in 2011.
Their skin harbors external parasites, such as mites and ticks, which may be eaten by oxpeckers and egrets.
Such behaviour was originally thought to be an example of mutualism, but recent evidence suggests that oxpeckers may be parasites instead, feeding on rhino blood.
Black rhinoceros are generally thought to be solitary, with the only strong bond between a mother and her calf.
In addition, males and females have a consort relationship during mating, also subadults and young adults frequently form loose associations with older individuals of either sex.
In September 2017, the birth of a calf raised the population to 19.
The park has dedicated rhino monitoring teams to protect the animals from poaching.
This concept is also used by the IUCN, listing three surviving subspecies and recognizing D. Between four and five million years ago, the black rhinoceros diverged from the white rhinoceros.
After this split, the direct ancestor of Diceros bicornis, Diceros praecox was present in the Pliocene of East Africa (Ethiopia, Kenya, Tanzania). bicornis evolved from this species during the Late Pliocene – Early Pleistocene. Two horns on the skull are made of keratin with the larger front horn typically 50 cm (20 in) long, exceptionally up to 140 cm (55 in).
The other African rhinoceros is the white rhinoceros (Ceratotherium simum).