Meeting Abstract
Squamates (lizards, snakes and amphisbaenians) that are derived from large- or medium-sized ancestors, and have acquired skull lengths that are less than or equal to 15 mm, are considered ‘miniaturized.’ Morphological characteristics associated with miniaturization have been identified in at least 21 of the 68 recognized squamate families, however, some of these characteristics have been studied only in a few species and the available information does not adequately represent the diversity within Squamata. Here, we evaluate all previously proposed skull characteristics associated with miniaturization and explore a published morphological dataset of 437 skull characteristics for 204 squamates to identify additional characteristics. The meta-analysis allows us to compile 21 traits associated with miniaturization. We find that phylogenetic history and skull design influence the way in which species become miniaturized, therefore there are not universal features that can be found in all miniaturized species. We corroborate general traits that are found in the majority of miniaturized squamates including: reduction of the post-temporal fenestra; reduction of the supratemporal fenestra; elongation of the skull; shifting of the occipital condyle to the posterior-most margin of the skull; and reduction of the paraoccipital process. We identified additional characteristics including: reduction in the number of postdentary bones, not only in fossorial species; loss of the splenial bone; and reduction in the number of dentary teeth. This meta-analysis indicates that jaw morphology is especially affected by miniaturization, therefore variation in this structure should be explored further in small reptiles, including living and fossil groups.
