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| Chilotherium schlosseri (Weber, 1905) and Eochilotherium samium (Weber, 1905) in Kampouridis, Svorligkou, Kargopoulos, Spassov et Böhme, 2023. |
ABSTRACT
Extant rhinoceroses are represented only by five species and are characterized by the presence of a nasal horn. In the past, they were much more diverse, with one of the best-known groups being the aceratheriines, i.e., hornless rhinoceroses. Chilotheres are a group of hornless rhinos that inhabited Eurasia during the Late Miocene. Their westernmost geographic range reached Eastern Europe, where overall eight species have been erected. Four of these were described based on material from the Upper Miocene of Samos Island (Greece), two of which are not considered valid anymore. Unfortunately, the type skulls of all four species are lost and there are several issues concerning their taxonomy. Therefore, we herein designate two skulls housed in historical collections from Samos as neotypes for the first two species, Chilotherium schlosseri (Weber, 1905) and Eochilotherium samium (Weber, 1905), and provide detailed comparisons for the separation of the species from each other and from any other chilotheres. Our results prove that the two species are valid and justify their separation on a generic level. Chilotherium schlosseri seems to be more closely affiliated with the other European Chilotherium species, whereas E. samium is more similar to the Chinese ‘Chilotherium’ wimani and ‘Chilotherium’ primigenium, based on their more plesiomorphic characters.
SYSTEMATIC PALEONTOLOGY
Class MAMMALIA Linnaeus, 1758
Order PERISSODACTYLA Owen, 1848
Family RHINOCEROTIDAE Gray, 1821
Subfamily ACERATHERIINAE Dollo, 1885 (sensu Lu, Deng, & Pandolfi, 2023)
Tribe ACERATHERIINI Dollo, 1885 (sensu Lu, Deng, & Pandolfi, 2023)
Subtribe CHILOTHERIINA Qiu, Xie, and Yan, 1987
Included Genera—Chilotherium Ringström, 1924,
Shansirhinus Kretzoi, 1942, and
Eochilotherium Geraads and Spassov, 2009.
CONCLUSIONS:
The European chilotheres have a very complicated taxonomic history, with the erection of over eight species. Herein, we attempt to solve some of the issues involving this group by designating neotypes for the first two described chilothere species from Europe, Chilotherium schlosseri and Eochilotherium samium, both from the Upper Miocene deposits of Samos Island (Greece). The revision showed that they represent two distinct taxa, with E. samium being placed in a distinct genus, based on some cranial features such as the missing depression in the frontal bones and its less complex dental morphology, such as the less pronounced protocone constriction. Chilotherium schlosseri represents one of the most derived species of the genus, based on its very widely separated parietal crests and its very complex tooth morphology, which frequently includes enamel plications. This species is closely allied with other Eastern European Chilotherium species, Chilotherium kowalevskii, Chilotherium sarmaticum from Ukraine and the Asian species Chilotherium orlovi from Kazakhstan. Eochilotherium samium on the other hand, seems to be more similar to the Chinese ‘Chilotherium’ wimani and ‘Chilotherium’ primigenium.
Panagiotis Kampouridis, Georgia Svorligkou, Nikolaos Kargopoulos, Nikolai Spassov and Madelaine Böhme. 2023. Revision of the Late Miocene hornless rhinocerotids from Samos Island (Greece) with the Designation of Neotypes and Implications for the European chilotheres. Journal of Vertebrate Paleontology. e2254360. DOI: 10.1080/02724634.2023.2254360
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