The motion permitted at a joint ranges from , such as where some skull bones interlock at a suture, to like that seen at the shoulder, where the humerus articulates with the scapula.

the cladogram shown here shows similarities and differences among several classes of vertebrates. anatomically, the four have limb structure as their common ancestor. we might separate the mammals from the other three classes because they a) divergent; do not lay eggs b) identical; are warm-blooded c) varied; a four chambered heart d) homologous; have mammary glands