An excellent example of the role of miniaturization in
the evolution of morphological novelty is the Mexican
salamander genus Thorius, shown in Figure 2. The 15
species of Thorius (only nine are formally named) represent the smallest salamanders known. Sexually mature
adults are as small as 1.3 cm, snout to vent (Hanken
1983a) they are clearly pushing the lower limit for body
size in terrestrial vertebrates. They are found under logs
or in leaf litter on the montane forest floor