Scolecophidian Morphological Adaptation to Little Life: Morphological evolution of the world’s smallest snakes

Reduction in body size poses significant constraints on morphological diversity within animals. Understanding the ways in which morphology is influenced by size is critical for evolutionary studies. In SMALL I will use scolecophidian snakes (Typhlopoidea, Leptotyphlopidae, and Anomalepididae) as a study system to examine how size drives morphology. Scolecophidia are highly specialised, miniaturised, obligately fossorial snakes. These snakes (approximately 500 extant species) lie outside the lineage comprising all other extant snakes (approximately 3,700 species) and thus have an important position in the evolutionary tree for understanding the origin and early evolution of snakes, especially as adaptation to fossoriality is likely to have facilitated the evolution of snakes from limbed lizard ancestors. Although fossoriality is often linked to reduction in body size, the impact of size on this important evolutionary transition has been understudied. Scolecophidia have an unappreciated amount of morphological diversity (including varying in total length by almost an order of magnitude) that may provide vital information about the early history of snakes, as well as about the implications of fossoriality and miniaturisation in vertebrate evolution. In SMALL, I will investigate the morphological diversity and evolution of scolecophidian snakes by: 1) Using microCT and diceCT, quantify morphological diversity of the different major lineages of scolecophidian snakes; 2) Using 3D geometric morphometrics on skeletal elements, discover the major axes of variation and to test for morphological convergence and divergence; 3) Using biogeographic modelling, examine the evolution of form and size across space and time.