| Chilotherium | |
|---|---|
| |
| A life restoration of Chilotherium anderssoni | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Perissodactyla |
| Family: | Rhinocerotidae |
| Genus: | †Chilotherium Ringström, 1924 |
| Referred species | |
| |
Chilotherium is an extinct genus of rhinoceros endemic to Eurasia during the Miocene through Pliocene living for 13.7—3.4 mya, existing for approximately 10.3 million years.
Description[]
It was a large, robust animal reaching 1.5-1.8 m in height and a weight between 1 and 2.5 tons, depending on the species.
Both sexes are horn-less. The lower jaw has a widened symphysial part and large tusk-like second incisors separated by a broad diastema. The limbs are very short and the body stout; the feet are tridactyl with diverging metapodials. Studying Chilotherium wimani, Chen et al. 2010 found a significant sexual dimorphism in the tusks and mandible, most notably the length of the tusks in males.
Geraads & Spassov 2009 argued that some features in Chilotherium, such as second incisors, mandible, cheek-teeth and other cranial features, are plesiomorphic, while some features in the tusks are apomorphic: the dorsal surface of the tusks in primitive species is turned latero-dorsally in more derived species while the medial edge has become very sharp and sickle-like and rotated dorsally, and thus a more effective cutting tool.
Chilotherium were a group of grazing animals that radiated into several subgenera and species. Their feet were tridactyl and their legs shorter than in related groups. A few of them remained browsers, but most of them were adapted to a grass-based diet, hence the short legs. Their heads were horn-less but equipped with tusk-like lower incisors and were held in a horizontal position, in contrast to modern rhinos. They inhabited the so-called sub-Paratethyan or Greek-Iranian province during the late Miocene when this region was invaded by advanced rhinos from Africa, such as Ceratotherium (modern white rhinos). Like them, Chilotherium gradually evolved into specialised grazers, including hypsodont teeth and shortened metapodials.
Species[]
Twelve species of Chilotherium have been described and 19 other species have been assigned the genus. Nine are considered valid: four from Europe, one from Iran, and four from China.
Aprotodon differs from Chilotherium in its proportionally larger and wider symphysis; the horizontal mandibular ramus is curved both in side view and in dorsal view, unlike most rhinocerotids; and the premolars are semi-molariform, unlike the fully molariform premolars in Chilotherium. In Subchilotherium the mandibular symphysis is much more narrow than in Chilotherium. Acerorhinus has a strongly constricted nasal base and a mandibular symphysis that is narrow compared to that in Chilotherium.
| Species | Revised species | Location |
|---|---|---|
| Chilotherium blanfordi (Lydekker, 1884) | Aprotodon blanfordi (Lydekker, 1884) | Siwalik |
| Chilotherium fatehjangense (Pilgrim, 1910) | Aprotodon fatehjangense (Pilgrim, 1910) | Siwalik |
| Chilotherium smith-woodwardi (Foster-Cooper, 1915) | Aprotodon smith-woodwardi Foster-Cooper, 1915 | Siwalik |
| Chilotherium ibericum Antunes, 1972 | Hispanotherium matritense (Prado, 1863) | Portugal |
| Chilotherium quintanelensis Zbyszewski, 1952 | Hispanotherium matritense (Prado, 1863) | Portugal |
| Chilotherium zernowi (Borissiak, 1915) | Acerorhinus zernowi (Borissiak, 1915) | Odessa |
| Chilotherium palaeosinense (Ringström, 1924) | Acerorhinus palaeosinensis (Ringström, 1924) | China |
| Chilotherium hipparionum (Koken, 1885) | Acerorhinus hipparionum (Koken, 1885) | China |
| Chilotherium tsaidamense (Bohlin, 1937) | Acerorhinus tsaidamensis (Bohlin, 1937) | China |
| Chilotherium intermedium (Lydekker, 1884) | Subchilotherium intermedium (Lydekker, 1884) | Siwalik |
| Chilotherium tanggulaense Zheng, 1980 | Subchilotherium intermedium (Lydekker, 1884) | Siwalik |
| Chilotherium pygmaeum (Ringström, 1927) | Subchilotherium pygmaeum (Ringström, 1927) | China |
| Chilotherium brancoi (Schlosser, 1903) | Shansirhinus brancoi (Schlosser, 1903) | China |
| Chilotherium yunnanensis Tang et al., 1974 | Shansirhinus brancoi (Schlosser, 1903) | China |
| Chilotherium tianzhuensis Zheng, 1982 | Shansirhinus ringstromi Kretzoi, 1942 | China |
| Chilotherium cornutum Qiu & Yan, 1982 | Shansirhinus ringstromi Kretzoi, 1942 | China |
| Chilotherium samium (Weber, 1905) | Chilotherium samium (Weber, 1905) | Samos |
| Chilotherium schlosseri (Weber, 1905) | Chilotherium schlosseri (Weber, 1905) | Samos |
| Chilotherium ponticum (Niezabitowski, 1912) | Chilotherium schlosseri (Weber, 1905) | Samos |
| Chilotherium ponticum (Niezabitowski, 1912) | Chilotherium schlosseri (Weber, 1905) | Samos |
| Chilotherium wegneri (Andree, 1921) | Chilotherium schlosseri (Weber, 1905) | Samos |
| Chilotherium kowalevskii (Pavlow, 1913) | Chilotherium kowalevskii (Pavlow, 1913) | Odessa |
| Chilotherium angustifrons (Andree, 1921) | Chilotherium kowalevskii (Pavlow, 1913) | Samos |
| Chilotherium kiliasi (Geraads & Koufos, 1990) | Chilotherium kiliasi (Geraads & Koufos, 1990) | Pentalophos |
| Chilotherium anderssoni (Ringström, 1924) | Chilotherium anderssoni (Ringström, 1924) | China |
| Chilotherium planifrons (Ringström, 1924) | Chilotherium anderssoni (Ringström, 1924) | China |
| Chilotherium fenhoensis (Tung et al., 1975) | Chilotherium anderssoni (Ringström, 1924) | China |
| Chilotherium habereri (Schlosser, 1903) | Chilotherium habereri (Schlosser, 1903) | China |
| Chilotherium gracile (Ringström, 1924) | Chilotherium habereri (Schlosser, 1903) | China |
| Chilotherium wimani (Ringström, 1924) | Chilotherium wimani (Ringström, 1924) | China |
| Chilotherium xizangensis (Ji et al., 1980) | Chilotherium xizangensis (Ji et al., 1980) | China |
| Chilotherium persiae (Pohlig, 1885) | Chilotherium persiae (Pohlig, 1885) | Maragha |
