Data from: Foraging mode constrains the evolution of cephalic horns in lizards and snakes

A phylogenetically diverse minority of snake and lizard species exhibit
rostral and ocular appendages that substantially modify the shape of their
heads. These cephalic horns have evolved multiple times in diverse
squamate lineages, enabling comparative tests of hypotheses on the
benefits and costs of these distinctive traits. Here, we demonstrate
correlated evolution between the occurrence of horns and foraging mode. We
argue that although horns may be beneficial for various functions (e.g.,
camouflage, defence) in animals that move infrequently, they make active
foragers more conspicuous to prey and predators, and hence are
maladaptive. We therefore expected horns to be more common in species that
ambush prey (entailing low movement rates) rather than in actively
searching (frequently moving) species. Consistent with that hypothesis,
our phylogenetic comparative analysis of published data on 1,939 species
reveals that cephalic horns occur almost exclusively in sit-and-wait
predators. This finding underlines how foraging mode constrains the
morphology of squamates and provides a compelling starting point for
similar studies in other animal groups.