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''Eritherium'' is an extinct genus of early Proboscidea found in the Ouled Abdoun basin (early Thanetian age), Morocco. It lived about 60 million years ago. It was first named by Emmanuel Gheerbrant in 2009 and the type species is ''Eritherium azzouzorum''. ''Eritherium ''is the oldest, smallest and most primitive known elephant relative. ==Description== The holotype (specimen number MNHN PM69) is now in the Musée d'histoire naturelle - Guimet in Lyon and includes an upper jaw (with approaches of the zygomatic bone and two maxillary branches, each of the two posterior premolars (P3 and 4) and three molars (M1-3)). The piece is about 6 inches long, 5 inches wide and just over 3 inches high. In addition, the fossils include 15 more objects including the skull bones (frontal and nasal bones), lower jaw fragments and teeth and the upper and lower jaw. Generally, ''Eritherium ''shared similarities in the structure of their teeth with other Paenungulata such as the extinct Embrithopoda or early representatives of the manatees, but their teeth are more specialised. The dentition of the mandible that was reconstructed (from two left fragments) made up the complete sequence of the original teeth of mammals: with three incisors, one canine, four premolars and three molars. The tooth row was closed and had no diastema between the canine tooth on the front and back teeth. This primitive mammalian dentition is unique among Proboscideans. The molars were generally bunodon (i.e. with small enamel cusps on the occlusal surface-bearing structure). Between these bumps were approaches for forming transverse strips on the first two molars and on the rearmost molar, which is typical in lophodont teeth. The premolars had only one (lower jaw) or two (in the maxilla) cusps. The first incisor is relatively large and asymmetric and already showed signs of reduction. These facts link ''Eritherium ''with other early Proboscideans. Another primitive characteristic is the short symphysis of the mandible. The reconstruction of the upper portion of the skull showed that the eye socket was relatively far forward in the skull. This is to be noted, given most other early Paenungulata had an orbit significantly shifted to the rear position of the skull. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Eritherium」の詳細全文を読む スポンサード リンク
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