Elephas celebensis
| Elephas celebensis Temporal range: Late Pliocene - Early Pleistocene
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|---|---|
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Proboscidea |
| Family: | Elephantidae |
| Genus: | Elephas |
| Species: | E. celebensis
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| Binomial name | |
| Elephas celebensis Hooijer, 1949
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Elephas celebensis or the Sulawesi dwarf elephant is an extinct species of elephant.
Description
The Sulawesi dwarf elephant (Stegoloxodon celebensis or Elephas celebensis) was about half the size of Archidiskodon (=Mammuthus) planifrons to which it was initially considered to be related by Dirk Albert Hooijer in 1949.[1] The most evident difference with the latter is the presence of functional lower tusks in some individuals. This was considered as paedomorphosis, a retention of juvenile characters in the adult stage, by Vincent Maglio in his revision of the proboscideans in 1973.[2] He based his conclusion on the presence of vestigial incisive germs in mandibles of Mammuthus planifrons. This idea was followed by Hooijer in 1974.[3]
Ancestry and taxonomy
The retention of functional lower tusks is, however, not seen in juveniles of otherwise single paired tuskers, so cannot be considered a paedomorphic feature proper. It is simply a retention of a primitive character, as seen in the African elephantid genera Primelephas and Stegotetrabelodon, and possibly the earliest forms of Elephas planifrons. Between the late 1980s and early 1990s, an Indonesian-Dutch team excavated more material, including a fairly complete but rather distorted skull. All material, new as well as old, is described and revised in Van den Bergh’s thesis of 1999 on the Indonesian elephantoids, with a discussion on taxonomy.[4] He puts question marks, “Elephas”, to indicate the uncertain taxonomical position, following Paul Sondaar’s approach of 1984.[5] Van den Bergh accepts a possible relation with “Elephas” indonesicus from Ci Pangglosoran near Bumiayu on Java, dated to the same geological period. Also this specimen was originally assigned to Elephas (= Mammuthus) planifrons, but was later renamed Stegoloxodon indonesicus by Kretzoi in 1950.[6] Recently, Georgi Markov and Haruo Saegusa made a further step and synonymized “Elephas” with Stegoloxodon in 2008.[7]
Distribution
The genus Stegoloxodon is restricted to Java and Sulawesi. The exact relation between the two endemic species is unclear, because the Javan species is known only by a single molar.
Fossils of the Sulawesi dwarf elephant are found in the Walanea Formation, dated to the Late Pliocene - Early Pleistocene. The single fossil of the Javanese species was found at Ci Pangglosoran near Bumiayu on Java,[8] dated to the same geological period.
References
- ^ Hooijer, D.A .(1949). Pleistocene Vertebrates from Celebes. IV. - Archidiskodon celebensis nov spec. Zoologische Mededelingen, Museum Leiden 30: 205–226.
- ^ Maglio, V.J. (1973). Origin and evolution of the Elephantidae. Transactions of the American Philosophical Society Philadelphia Volume 63. American Philosophical Society, Philadelphia. Pp. 149
- ^ Hooijer, D.A. (1974). Elephas celebensis (Hooijer) from the Pleistocene of Java. Zoologische Mededelingen, Museum Leiden, 48: 85–93.
- ^ Bergh, G.D. van den, 1999. The Late Neogene elephantoid-bearing faunas of [Indonesia and their palaeozoogeographic implications; A study of the terrestrial faunal succession of Sulawesi, Flores and Java, including evidence for early hominid dispersal east of Wallace's line, Scripta Geologica 117: 1-419 [1]
- ^ Sondaar, P.Y., 1984. Faunal evolution and the mammalian biostratigraphy of Java. Courier Forschungsinstitut Senckenberg 69: 219-235.
- ^ Kretzoi, M., 1950. Stegoloxodon nov. gen., a loxodonta elefantok esetleges azsiai ose (Stegoloxodon nov. gen., a possible Asiatic ancestor of true loxodonts). Foldtani Kozlony 80: 405-408 [In Hungarian and English].
- ^ Markov, G.N. and Saegusa, H., 2008. On the validity of Stegoloxodon Kretzoi, 1950 (Mammalia: Proboscidea). Zootaxa 1861: 55-56.
- ^ Van der Maarel, F.H., 1932. Contributions to the knowledge of the fossil mammalian fauna of Java. Wetenschappelijke Mededelingen Dienst van den Mijnbouw in Nederlandsch-Indie 15: 1-208.