Miniaturization is a phylogenetic concept, which has been defined as the evolution of extremely small adult size in a lineage. The effects of miniaturization at the organismic level extend to all biological aspects, from physiological changes to ecological and ethological ones. With regard to morphological consequences, miniaturization does not simply imply the decrease of the body size of the adult; it usually results from complex modifications of the presumed ancestral ontogenetic trajectory as well as structural modifications to maintain functional efficiency. However, the actual mechanism that leads to a strikingly diminished adult size may vary in each taxon.

This evolutionary phenomenon has been proposed as a key factor for the phyletic diversification above the species level and the evolution of major clades, which is consistent with three phenomena of potential significance as sources of morphological diversity that have been documented in miniaturized taxa: 1) increased intraspecific vatiation, 2) simplification and structural reduction, and 3) morphological novelties. Among vertebrates, miniaturization has been considered as a factor involved in the origin of living amphibians, amniotes, snakes and lizards. Particularly, current phylogenetic hypotheses place the Paleozoic miniaturized temnospondyls amphibians as the closest relatives of frogs and salamanders, indicating that miniaturization could have played an important role in the origin of these extant groups. For my doctoral dissertation, I seek to recognize the potential micro and macroevolutionary effects of miniaturization in temnospondyl amphibians and to investigate the ontogenetic heterochronies that led to a decrease of body size in this group. It is expected that the study of the impact of miniaturization in temnospondyls will shed light on our understanding of this significant evolutionary phenomenon, and its role in the origin of living amphibians.