Influence of diet on prehension mode in cordylid lizards: a morphological and kinematic analysis

Lizards exhibit a variety of mechanisms to capture prey, including lingual prehension, jaw prehension and lingual pinning. Despite being the topic of numerous studies, the link between prehension mode and diet remains poorly understood, especially in clades where multiple prehension modes are present. We addressed this issue by comparing the feeding behaviour and tongue morphology of a termite-eating specialist Ouroborus cataphractus with that of a closely related dietary generalist Karusasaurus polyzonus. We used high-speed videography to test the effect of prey species (termite vs. small cricket) and prey size (small vs. large cricket) on prehension mode. In addition, we included several other cordylid lizards representing the major clades in the family into our analysis to examine whether the prehension modes present in O.cataphractus characterize all cordylid species or whether they represent isolated occurrences. Finally, we investigated the morphology of the tongue in Cordylidae, with emphasis on O.cataphractus and K.polyzonus, using light and scanning electron microscopy techniques. Our data showed that the consumption of termites in O.cataphractus has resulted in the evolution of a novel lingual prehension mode, during which the ventral surface of the tongue is used to apprehend prey. This is in contrast to other lizards, which use the dorsal surface of the tongue to contact prey. Moreover, we demonstrated that this novel lingual prehension mode is accompanied by distinct morphological elaborations of the tongue surface. None of the other cordylid lizards tested in our study used lingual prehension during prey capture, except K.polyzonus, which used the tongue in a very small percentage of feeding trials. Overall, this study suggests that dietary specialization might underlie the evolution of novel prehension mechanisms in lizards.