|
The Eothyrididae were a small group of very primitive, insectivorous synapsids. Only two genera are known, ''Eothyris'' and ''Oedaleops'', both from the early Permian of North America. Their main distinguishing feature is the large caniniform tooth in front of the maxilla. Eothyridids share with the Caseidae a number of specialised features associated with the morphology of the snout and external naris and it is likely that they were ancestral to them. The two together form the clade Caseasauria. ''Eothyris'' is known from a single skull specimen; ''Oedaleops'' is known from three partial skulls and some parts of some limbs. The skulls are approximately 6 centimeters in length, suggesting that the total length of the animals was under 1 meter. Both species were found in the lower Permian in what is today North America. In modern cladistics, the Eothyrididae are considered to be a basal group within the Caseasauria. Caseasauria forms a sister group of the Eupelycosauria, out of which the Therapsids (the "mammal-like reptiles") evolved. ==See also== * Evolution of mammals 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「Eothyrididae」の詳細全文を読む スポンサード リンク
|