Salamanders
 

Figure 2. Lungless salamanders, such as this Bolitologlossa peruviana, have protruding tongues.

  
Salamanders have the most generalized tetrapod body form 
with four limbs and a tail. Their locomotion is probably very 
similar to that employed by the primitive tetrapods. 
While walking, salamanders combine a lateral bending of the 
body with leg movements. All salamanders have long tails and 
all but a few have robust and well functional limbs 
(two aquatic families having reduced limbs). 
Salamander skulls are reduced by the loss of many bony 
elements and by the presence of numerous cartilaginous parts. 
Bony elements that are never found in salamanders include: 
postorbital, jugal, quadratojugal, postfrontal, postparietal,
supratemporal, supraoccipital, basioccipital and ectopterygoid. 
 
In general, the skull of salamanders  is much less compact than 
that of caecilians and more robust than that of anurans. 
The temporal fossae are open, the orbits large, with a 
generally poorly roofed nasal region. The cranial structure of 
salamanders is highly variable depending on the aquatic or 
terrestrial lifestyle of the adults, but salamanders always have 
an incomplete maxillary arch and a poorly developed 
neurocranium (Fig. 1, see figures from the overheads).

Ribs are present, but are very reduced as in the other two 
amphibian lineages. Because salamanders do not have a 
rib cage, their respiration is regulated by a buccopharyngeal 
pump that forces air from the mouth to the lungs. This pumping 
system is formed by elements of the hyobranchial apparatus. 
Because the adaptation that allows some salamanders to 
protrude their tongue also relies on the hyobranchius apparatus,
only lungless salamanders (i.e., Plethodontids) have 
well-protruding tongues (Fig.2). 

Many salamander groups display paedomorphosis (= neoteny). 
Paedomorphic forms are recognized by the retention of larval 
traits during adulthood: larval tooth and bone patterns 
(e.g., maxillae absent), no eyelids, retention of a functional 
lateral-line system and external gills, etc.