The evolution of the appendages during the fin-to-limb transition has been extensively studied, yet the majority of studies focused on the skeleton and the fossil record. Whereas the evolution of the anatomy of the appendicular musculature has been studied, the changes in the muscular architecture during the fin-to-limb transition remain largely unstudied, yet may provide important new insights. The fin-to-limb transition is associated with the appearance of a new mode of locomotion and the associated shift from pectoral to pelvic dominance. Here, we propose ways to investigate this question and review data on muscle mass and muscle architecture of the pectoral and pelvic muscles in extant vertebrates. We explore whether changes in appendage type are associated with changes in the muscular architecture and the relative investment in different muscle groups. These preliminary data show a general increase in the muscle mass of the appendages relative to the body mass during the fin-to-limb transition. The locomotor shift suggested to occur during the fin-to-limb transition appears supported by our preliminary data since in ‘fish’ the pectoral fins are heavier than the pelvic fins, whereas in tetrapods, the forelimb muscles are less developed than the hind limb muscles. Finally, a shift in the investment in different muscle groups with an increase of the contribution of the superficial groups in tetrapods compared to ‘fish’ appears to take place. Our study highlights the potential of investigating quantitative features of the locomotor muscles, yet also demonstrates the lack of quantitative data allowing to test these ideas.

中文翻译：

---

鳍到肢过渡期间附肢肌肉的演变：通过软组织研究的可能见解，一个观点。

鳍到肢过渡期间附属物的进化已被广泛研究，但大多数研究集中在骨骼和化石记录上。尽管已经研究了附肢肌肉组织解剖结构的演变，但在鳍到肢过渡期间肌肉结构的变化仍然很大程度上未经研究，但可能会提供重要的新见解。鳍到肢的过渡与新运动模式的出现以及相关的从胸骨到骨盆优势的转变有关。在这里，我们提出了调查这个问题的方法，并回顾了现存脊椎动物胸肌和骨盆肌肉的肌肉质量和肌肉结构的数据。我们探索附肢类型的变化是否与肌肉结构的变化和不同肌肉群的相对投资有关。这些初步数据显示，在鳍到肢的过渡期间，附属器的肌肉质量相对于体重普遍增加。我们的初步数据似乎支持在鳍到肢过渡期间发生的运动转变，因为在“鱼”中，胸鳍比腹鳍重，而在四足动物中，前肢肌肉不如后肢肌肉发达. 最后，与“鱼”相比，四足动物表面肌群的贡献增加，不同肌肉群的投资似乎发生了变化。我们的研究强调了研究运动肌肉定量特征的潜力，