chapter  6
Head and Neck Muscles of Amphibians
Pages 23

The main goal of Chapter 5 was to discuss the homologies and evolution of the muscles within the Sarcopterygii as a whole, and, thus, to provide a basis for works that would be more specifi cally concerned with each of the major sarcopterygian groups. The main goal of Chapter 6 is thus to use the information provided in Chapter 5 as a basis for a more detailed, specifi c analysis of the mandibular, hyoid, branchial and hypobranchial muscles of the three extant amphibian taxa, i.e., salamanders (Caudata, or Urodela), frogs (Anura), and caecilians (Gymnophiona). This is an opportune moment to undertake a review of the comparative anatomy, homologies and evolution of these muscles within amphibians because studies published in this past decade have provided new information about the ontogeny of the cephalic muscles in representatives of each of these amphibian groups, which is particularly useful in analyzing the homologies of these muscles within these groups (e.g., Olsson et al. 2000, 2001; Palavecino 2000; Chanoine and Hardy 2003; Ericsson and Olsson 2004; Ericsson et al. 2004; Kleinteich and Haas 2007; Piekarski and Olsson 2007; Zierman and Olsson 2007). In addition, Carroll has (2007) published an excellent, extensive review on the phylogeny and evolution of caecilians, urodeles and anurans, which provides the phylogenetic background for our discussions about plesiomorphic versus derived traits within the amphibians. As explained by this latter author, the extant amphibians are included in three main groups: caecilians (Gymnophiona or Caecilia sensu Carroll 2007), frogs (Anura), and salamanders (Caudata, or Urodela), the two latter groups being possibly more closely related to each other than to the caecilians (see Fig. 1.1, Chapters 1 and 2, and text below).