The genus Ceratotherium belongs to the tribe Dicerotini (also spelled Diceroti) or subtribe Dicerotina, indicating a closer evolutionary relationship to the genus Diceros (which includes the black rhinoceros) than to other extant rhinoceros genera.[3]
The evolutionary history of Ceratotherium includes several recognized and debated fossil species:
- Ceratotherium mauritanicum: An extinct species known from the Pleistocene of North Africa. Some Pliocene East African remains, alternatively attributed by some authors to Ceratotherium efficax,[4] are sometimes included in C. mauritanicum. Depending on the inclusion of these East African materials, C. mauritanicum has been considered either ancestral to the modern white rhinoceros or a distinct evolutionary offshoot.[5]
- Ceratotherium praecox: Remains from the Late Miocene and Pliocene (approximately 7–3 million years ago) of East Africa were once assigned to this species. However, C. praecox is now largely considered a member of the genus Diceros (as Diceros praecox), primarily because its type material aligns more closely with that genus. Some fossil material historically attributed to C. praecox may still represent true, albeit currently unassigned, Ceratotherium material.[6][5]
- "Ceratotherium" neumayri?: This Late Miocene species from Europe and Western Asia is questionably placed within Ceratotherium. Some studies suggest it may be more closely related to Diceros, ancestral to both genera, or represent an early offshoot. Alternative classifications have assigned it to Diceros or the monotypic genus Miodiceros.[3]
- Ceratotherium germanoafricanum: This taxon encompasses remains from East Africa dating from approximately 3 to 1 million years ago. Some researchers propose it as a potential ancestor to the modern white rhinoceros. Others view it as a subspecies of C. simum or assign these fossils to other species like C. mauritanicum.[5]
Other potential early relatives and disputed species:
- Ceratotherium advenientis: Known from the Late Miocene of southern Italy (then part of the African plate).[7]
- "Ceratotherium" douariense: From the Late Miocene of Tunisia (around 7 million years ago). Its assignment to Ceratotherium is debated, with some authors placing it in Diceros (as Diceros douariensis).[7]
- Ceratotherium? primaevum: Reported from Algeria (around 10 million years ago), with other possible remains from East Africa. Its generic placement remains uncertain.[7]
The earliest fossils definitively attributed to the extant white rhinoceros (Ceratotherium simum) date to the Early Pleistocene in East Africa, approximately 1–2 million years ago, although the exact timing can vary depending on which specific fossil remains are included in the species' diagnosis.[5]
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