We have examined the morphology of the skeletal elements involved in constricted-based tail autotomy in Neotropical plethodontid salamanders of the genus Bolitoglossa. Observed variation in the transverse processes of the first caudal vertebra ranges from a relatively generalized condition, similar to that seen in North American species, to morphologically specialized structures found only in tropical species. Here we present evidence that most species of Bolitoglossa have evolved hypertrophied, reversed transverse processes whose shape and size go beyond what is necessary for structural support in constricted-based tail autotomy and allow the autotomized tail to be used as an anti-predator weapon. We discuss the evolutionary implications of this mechanism.