ABSTRACT
The few comparative forelimb myological analyses directly based on dissections of members of diverse taxa (e.g., sarcopterygian fish, amphibians, reptiles, monotremes, and therian mammals, including humans) were published. This chapter focuses on tetrapods, particularly how the pectoral and forelimb muscles have evolved during the transitions from nonmammalian tetrapods to monotreme, marsupial, and placental mammals, including primates and modern humans. It includes new detailed data and figures of the forelimb muscles of opossums and other marsupials that are based on our own recent dissections and works performed by others, as well as more details on primate and human evolution including recent data on the least studied apes, the bonobos. The chapter discusses related notions, such as that of Bauplan, or "body plan," which was originally related to a preevolutionary notion of "archetype" in the sense that it refers to a "plan.".
