Dentition and diet in snakes: adaptations to oophagy in the Australian elapid genus Simoselaps

Most small fossorial proteroglyphous Australian snakes of the genus Simoselaps feed on adult lizards, but the species of one lineage (the semifasciatus group) feed exclusively on the eggs of squamate reptiles. Examination of cleared, alizarin preparations showed that dentition of the saurophagous species is similar to that of other elapids, but dentition of the oophagous taxa is highly modified. The anterior (palatine and maxillary) teeth other than the fangs are reduced in size and number whereas those of the pterygoid (and in S. ‘ropert’, the dentary) are enlarged posteriorly, becoming compressed along a longitudinal plane and angled medially. The shape of the pterygoid and quadrate is also modified. 

Two Simoselaps species with broader diets (eating both adult lizards and their eggs) show typical ‘saurophagous’ dentition in one case, ‘oophagous’ dentition in the other, showing that either type of dentition can be used to capture and ingest either type of prey. We suggest functional explanations for the dentitional modifications in the egg‐eating snakes, primarily in terms of the advantages of applying considerable force to the eggshell. Oophagous modifications within Simoselaps are convergent with those seen in several independently‐derived lineages of oophagous colubrid snakes, but (perhaps because of the presence of the fang) differ in having the enlarged blade‐like teeth on the pterygoid or dentary rather than the maxilla.