Stegotetrabelodon

Lower jaw of Stegotetrabelodon syrticus

Stegotetrabelodon is an extinct genus Proboscidea, which in Europe ( eg Italy), West Asia and Africa lived in the late Miocene to the early Pliocene from 7.5 to 4.5 million years ago. He is one of the earliest representatives of the family of Elephantidae and was characterized by the presence of tusks in the upper and lower jaw.

Features

Stegotetrabelodon represents a major representative of the mammoths and possessed both the upper and lower jaw tusks. Those of the upper jaw were slightly curved upwards and long straight shape with untrained tooth enamel, which were of the lower jaw also long, but. In addition, they were narrowed laterally, so as to have an oval cross-section with a maximum of 7 and a minimum of 4 cm diameter. The mandible was still relatively slim, but had a vigorous and downward symphysis. The molars already reported the typical for the genuine elephant lamellar structure, but the individual lamellae were partially clear two divided into an inner and outer enamel folding part and gave the occlusal surface of a höckriges ( bunodontes ) appearance. In contrast to related Tetralophodon but there was already clear evidence of the coalescence of these lamellae parts, mainly significantly stepped to the fore on the last molar. The width of the melting wrinkles was very large. Furthermore, the molars had a high proportion of dental cement. The first and second molar shown typically four and the last seven or more melting wrinkles. This was with a length of up to 32 cm and the largest cheek teeth in the dentition. Furthermore Build the class are already strongly resembled today's elephants.

Fossil finds

Finds of Stegotetrabelodon are restricted to Africa and western Eurasia. The oldest finds are previously known from Uganda from the Oluka lineup. Ancient remains from Europe are occupied by a lower jaw Cessanity in Italy and is one of the northernmost representative. In addition, fossils have been described from the Arabian Peninsula ..

System

With his typical laminated molars Stegotetrabelodon belongs to the family of Elephantidae that forms the evolutionarily youngest member of the superfamily Elephantoidea within the Proboscidea addition to Stegodonten. However, an assignment within the superfamily Gomphotherioidea was considered originally. Among the elephants because of his tooth construction it represents a rather primitive representatives and stands outside the subfamily Elephantinae, composed of the extant elephants. The closest relative is Stegodibelodon from which, however, are known only to a few finds.

Stegodontidae

Stegotetrabelodon

Stegodibelodon

Primelephas

Loxodonta

Elephas

Mammuthus

Two types are recognized within Stegotetrabelodon:

  • S. lybicus Petrocchi, 1943
  • S. syrticus Petrocchi 1941

Discussions will continue the independence of S. orbus, which is often considered to be synonymous with S. syrticus, but shorter lower jaw tusks and a somewhat different symphysis possessed. A potentially new species with P. sp. described from Uganda. Other species such as S. lehmani or S. maluvalensis originally described are nowadays more likely to Tetralophodon or Stegolophodon while as " Mastodon " grandincisivum described and partly Asked to Stegotetrabelodon tusker in the closer relationship belongs rather to Amebelodon. Likewise, the numerous, described from China Stegotetrabelodon alleged fossils are also assign phylogenetically older proboscidean.

The origin of Stegotetrabelodon is most likely in central Africa and dated to the late Miocene, more than seven million years ago. As previous form is possibly Tetralophodon to look at. Before nearly seven million years, the proboscis species is then detected also in Europe and western Asia. Her last appearance they had in the early Pliocene, about 4.5 million years ago in North Africa.

Mya (unit) Afrotheria
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