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. The most evident difference with the latter is the presence of functional lower tusk

Tusk

Tusks are elongated, continuously growing front teeth, usually but not always in pairs, that protrude well beyond the mouth of certain mammal species. They are most commonly canines, as with warthogs, wild boar, and walruses, or, in the case of elephants and narwhals, elongated incisors...

s 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. He based his conclusion on the presence of vestigial incisive germs in mandibles of Mammuthus planifrons. This idea was followed by Hooijer in 1974.

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 Mammuthus 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. He puts question marks, “Elephas”, to indicate the uncertain taxonomical position, following Paul Sondaar’s approach of 1984. 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

Miklós Kretzoi

Miklós Kretzoi was a Hungarian geologist, paleontologist and paleoanthropologist and Széchenyi Prize winner....

 in 1950. Recently, Georgi Markov and Haruo Saegusa made a further step and synonymized “Elephas” with Stegoloxodon in 2008.

Distribution

The genus Stegoloxodon is restricted to Java

Java

Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...

 and Sulawesi

Sulawesi

Sulawesi is one of the four larger Sunda Islands of Indonesia and is situated between Borneo and the Maluku Islands. In Indonesia, only Sumatra, Borneo, and Papua are larger in territory, and only Java and Sumatra have larger Indonesian populations.- Etymology :The Portuguese were the first to...

. 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, dated to the same geological period.