Abstract: Discoveries of new extant or fossil forms have historically changed the hypotheses of relationship of tetrapods, not the appearance of new theories. At present a sister group relationship between tetrapods and elpistostegids and that of these two groups to osteolepiforms is accepted. A comparison of recent hypotheses on the interrelationships of sarcopterygians demonstrates that three hypotheses of the relationship of lungfishes to sarcopterygians except close to tetrapods nearly have the same probability. New basal sarcopterygians with new characters or new interpretations of the polarization of character states may solve the placement of lungfishes.

摘要： 研究历史表明，导致四足动物亲缘关系的假说发生变化是现生或化石种类的发现，而不是新学说的出现。目前，四足动物与希望螈类(elpistostegids)，以及这两个类群与骨鳞鱼类的姊妹群关系已被接受。通过比较肉鳍鱼类相互关系的最新假说，可以看出其中三种假说可能性最大，概率几乎相同，即肺鱼不是四足动物的近亲而与不同的肉鳍鱼类可能有亲缘关系。具新性状的基位肉鳍鱼类的发现或者性状状态极向的重新解释会有助于解决肺鱼类在支序图中的位置。