Rodents are particularly interesting because they represent the most prosperous of mammal groups and are highly diversified from an ecological viewpoint. Their wide range of dental characteristics coupled with their numerous locomotory adaptations, which have enabled them to colonise many habitats and environments, can partly explain their ecological ubiquity. Rodents are characterised by one continuously growing incisor and up to four or five cheek teeth per jaw quadrant, separated by a large diastema. In addition to their high reproductive rates and their short breeding cycle, their singular and complex dentitions have also contributed to their evolutionary success since 55 My.
Teeth are one of the best indicators of major diversification and adaptive events among extinct rodents because they constitute the most well-preserved tissue found in the fossil record, owing to their very high degree of mineralisation. Specific diversity and ecological data are classically inferred by paleontologists according to the variable complexity of occlusal dental patterns, especially for premolars and molars (e.g. Stehlin and Schaub, 1951; Misonne, 1969; Vianey-Liaud, 1991; Korth, 1994; Dawson, 2003). Based on the arrangement, shape and connections of cusps, the main component of feeding habits can be estimated. More precisely, bunodont patterns generally indicate an omnivorous feeding habit with the inclusion of fruits, seeds, leaves and occasionally insects in the diet. Acute cusps, which are rarely as sharp in rodents as in mammals having true secodont patterns, correspond to insectivorous to carnivorous diets. Patterns with crests or flat wear generally correspond to consumption of fibrous and abrasive plants. The dental trends listed in rodents are shared by most mammals (Janis and Fortelius, 19). Buno-lophodonty is the most frequent pattern found in extant rodents and reflects predominance towards omnivorous to herbivorous feeding habits. Crown size is another indicator of rodent lifestyle. Indeed, high-crown teeth clearly represent an adaptation to prevent erosion from intense wear (Koenigswald, 2011) resulting from the ingestion of abrasive particles present in grasses (i.e. hard silica phytoliths), present on herbaceous plants in open environments or on underground plants (i.e. dust and grit).