【摘要】 四足动物的起源是生物进化过程中的关键问题之一。2006年,美国学者Daeschler E B和Shubin N H在加拿大努纳武特地区南部的埃勒斯米尔岛上发掘了一系列距今3.75亿年的Tiktaalik鱼化石。该鱼与希望螈(Elpisto-stegalian)一样均没有背鳍、没有鳃盖、子鳃盖、外肩胛骨;而具有宽大的背腹性明显的扁平颅骨,以及位于颅骨背面的眼睛,还具有成对的额骨、微鼻孔和位于末端的口,并具备了四足动物的一些特征,诸如较大的通气孔、可活动的颈部、伏瓦状排列的肋骨,胸鳍出现了挠骨的分化,并有骨质关节。这一发现填补了从海洋动物到四足动物的空白。更多还原

【Abstract】 The origin of tetapod is one of the crucial problems in biological evolutionary process.The latest achievement was introduce in this research.In 2006,American scholar Daeschler E B and Shubin N H discovered that a well-preserved species of 375 million year fossil Tiktaalik fish from Southern Ellesmere Island,Nunavut Ferritory,Canada.This fish is more similar to Elpistostegalian.They both lack the anterior dorsal fins,the opercular,subopercular,extrascapulars and possess broad,dorsoventrally compressed skulls with dorsally placed eyes,paired frontal bones,marginal nares,and a subterminal mouth.In addition,the fish has the tetrapod-like features,such as wider spiracular tract,a mobile neck,dorsally placed eyes,imbricate ribs and a pectoral girdle.Pectoral fin appeared branch of radials,and it had bonejoints.New discoveries of Tiktaalik fossils fill in the gaps from ocean animals to tetapods.更多还原