Hutchinson John R
Biomechanical Engineering Division, Stanford University, Durand 209, BME, Stanford, CA 94305-4038, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2002 Dec;133(4):1051-86. doi: 10.1016/s1095-6433(02)00158-7.
The anatomy and functions of muscle-tendon complexes and their bony attachments in birds and their outgroups show how the major pelvic limb muscle groups evolved. Fossils reveal that most changes evolved after the divergence of archosaurs in the Triassic, particularly in the dinosaurian precursors to birds. Three-dimensional limb control became concentrated at the hip joint; more distal joints and muscles were restricted to flexion or extension early in dinosaur evolution. Hip extensors expanded even though the primary femoral retractor M. caudofemoralis longus was reduced. Hip flexors and two-joint "hamstring" muscles were simplified to a few large heads. Knee extensors increased their sizes and moment arms early in bipedal dinosaurs, but the patella and cranial cnemial crest evolved later in birds. Lower limb muscles expanded as ossifications such as the hypotarsus increased their moment arms. The ossification of lower limb tendons, particularly in extensors, is a recent novelty of birds. Muscles and tendons that develop large forces, stresses, and moments to stabilize or move the limbs became increasingly prominent on the line to birds. Locomotion evolved in a stepwise pattern that only recently produced the derived limb control mechanisms of crown-group birds, such as the strongly flexed hip and knee joints.
鸟类及其外类群中肌肉 - 肌腱复合体及其骨骼附着点的解剖结构和功能，展示了主要盆肢肌群的进化方式。化石显示，大多数变化是在三叠纪主龙类分化之后发生的，特别是在鸟类的恐龙祖先中。三维肢体控制集中在髋关节；在恐龙进化早期，更远端的关节和肌肉仅限于屈伸运动。尽管主要的股后缩肌——长股尾股肌缩小，但髋伸肌却有所扩展。髋屈肌和双关节“腿筋”肌简化为几个大的肌头。在两足恐龙早期，膝伸肌增大了其尺寸和力臂，但髌骨和胫骨嵴在鸟类中出现得较晚。随着跗跖骨等骨化结构增大其力臂，下肢肌肉也有所扩展。下肢肌腱的骨化，尤其是伸肌中的骨化，是鸟类最近才出现的特征。在向鸟类演化的谱系中，那些为稳定或移动肢体而产生大力、应力和力矩的肌肉和肌腱变得越来越突出。运动是以逐步的方式进化的，直到最近才产生了冠群鸟类特有的肢体控制机制，比如强烈弯曲的髋关节和膝关节。
