Abstract
Patterns of distribution of larval, adult and specialized characters in the skull and jaw musculature are compared in the adult paedomorphic perennibranchiate urodelans ( Siren , Necturus , Proteus , Amphiuma , Megalobatrachus ) and neotenic axolotls ( Ambystoma mexicanum ). These patterns are essentially different in the neotenic and paedomorphic forms, and also in various species of the perennibranchiates. The neoteny (unhereditary ontogenetic modifications) and paedomorphosis (evolutionary hereditary transformations of ontogenesis) are quite different phenomena, in spite of external similarity of their phenotypic manifestations. The data under consideration do not correspond with the hypotheses assuming possibility of transformation of neoteny into paedomorphosis and high tempo of the paedomorphic macroevolution. The adaptive roles of some paedomorphic and specialized characters of the jaw apparatus in permanent-aquatic salamanders are discussed, with special attention to Amphiuma and Siren .
Published Version
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