. Chordate morphology. Morphology (Animals); Chordata. Among the living tetrapods, amphibians are best defined as lacking the amniote type of egg (see Chapter 7) and hav- ing a larval form that metamorphoses into the adult. The question here is whether or not there are also identifying cranial features. Living amphibians belong to three groups: the frogs and toads, the salamanders, and the Apoda or Gymnophiona. Only the first two groups will be described; the last contains little-known, worm-like, burrowing forms, the coecilians. A check-list of the bones of the amphibian head skeleton is give
. Chordate morphology. Morphology (Animals); Chordata. Among the living tetrapods, amphibians are best defined as lacking the amniote type of egg (see Chapter 7) and hav- ing a larval form that metamorphoses into the adult. The question here is whether or not there are also identifying cranial features. Living amphibians belong to three groups: the frogs and toads, the salamanders, and the Apoda or Gymnophiona. Only the first two groups will be described; the last contains little-known, worm-like, burrowing forms, the coecilians. A check-list of the bones of the amphibian head skeleton is given in Table 4-3. Salamander or urode/e Two American salamanders, Cryp- tobranchus alleghemensis (Figure 4-17) and Necturus maculatus, illustrate much of the range of variation seen in urodeles. In shape, the skulls of these two genera are quite unlike. Neither has retained an apparent outer roof, but the parie- tal bones form the top of the endocranium. Postparietals and supratemporals are lacking in this group as is the parietal foramen. The nasal and maxilla are lacking in Necturus but not in Cryptohranchus. Neither has a labial arch and the quadratojugal if present is fused to the quadrate. The prefrontal lacrimal frontal postorbital parietal. premaxilla maxilla palatine suprooccipital squamosal quadrate quadratojugal articular A dentary maxilla premaxilla splenial suproangular angular porasphenoid |uga| q"°d'°'°i"9°l palatine 1 \ / / -. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Jollie, Malcolm. New York, Reinhold
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