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''Ancalecetus'' (from Greek ''ankale'', "bent arm", and ''ketos'', "whale") is an extinct genus of early whale known from the Late Eocene (Priabonian, ) Birket Qarun Formation (, paleocoordinates ) in Wadi Al-Hitan, Egypt.〔. Retrieved July 2013.〕〔. Retrieved July 2013.〕 The species is named after anthropologist and primate researcher Elwyn L. Simons who discovered the type specimen in 1985.〔 The holotype is a partial cranium (the top of the skull was destroyed by erosion), both dentaries, 20 vertebrae and some sternal elements, partial ribs, and most of both forelimbs. ''Ancalecetus'' differs from other archaeocetes and modern whales in having narrow scapulae, very limited mobility in the shoulder joint, and fusion of the humerus, ulna, and radius at the elbow joint. In the wrist, the carpal bones are small like in ''Zygorhiza'', but, unlike in this other basilosaurid, the magnum is fused with the trapezoid in ''Ancalecetus''. ==Forelimbs== The well-preserved forelimbs are the most distinctive parts of ''A. simonsi''. A broad scapula and a ball-and-socket shoulder joint is characteristic of cetaceans, but ''Ancalecetus'' lacks both. The interior surface of the narrow scapula is not broadly curved as in most cetaceans, but tightly curved. The roughened vertebral border suggests the presence of a cartilaginous extension that extends the surface of the scapula like in modern cetaceans. Compared to other cetaceans, the infraspinous fossa is smaller, the caudal border is less curved and not oriented posteriorly. The glenoid cavity is very shallow and directed posteriorly, rather than ventrally like in other cetaceans. Likewise, the oddly folded acromion is pointing ventrally and posteriorly, and not anteriorly as in other cetaceans. Unlike in other basilosaurids, the humerus of ''Ancalecetus'' is flattened and has a relatively small head. The distal end has flat, textured surfaces for the articulation of the radius and ulna; these bones are fused on the left limb and tightly fitting and the right side, and neither permitted motion at the elbow joint.〔 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「Ancalecetus」の詳細全文を読む スポンサード リンク
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