Data for: The first description of dermal armour in snakes

Osteoderms, also called dermal armour, often play a role in predator
defence. The presence of osteoderms is highly irregularly distributed
across the squamate phylogeny and they have not been found in snakes. In
this study, we searched for candidate snake species that would benefit
from such armour to protect their body, focusing primarily on fossorial
species with defensive tail displays. We examined the tail morphology of
27 snake species from different families using micro-computed tomography
(µCT) and micro-radiography. We discovered dermal armour in four species
of sand boas (Erycidae) that also feature enlarged and highly modified
caudal vertebrae. This is the first description of dermal armour in
snakes. Ancestral state reconstructions revealed that osteoderms likely
evolved once or multiple times in Erycidae. We have not found osteoderms
in any other examined snake species. Nevertheless, similar structures are
known from unrelated squamate clades, such as gerrhosaurids and geckos.
This supports the idea of underlying deep developmental homology. We
propose the hypothesis that osteoderms protect sand boas like the
“brigandine armour” of medieval warriors. We interpret it as another
component of the sand boas' rich defence strategy.