Dental measurements do not diagnose modern artiodactyl species: Implications for the systematics of Merycoidodontoidea

Abstract

Though dental measurements are frequently used to diagnose the fossil species of Merycoidodontoidea and other extinct artiodactyls, the effective diagnosis of modern artiodactyl taxa via dental measurements has not been extensively tested. Our study finds that variation in artiodactyl dentition is generally higher than in primates, carnivores, rodents and even elephants, with molar coefficients of variation ranging up to 18% (Camelus bactrianus), and that dental measurements poorly diagnose modern artiodactyls via discriminant function analysis, adjusted t-tests on coefficients of variation, or finite mixture analysis. The higher-than-expected coefficients of variation for artiodactyls imply that some fossil taxa may be over-split, but the low utility of dental measurements in separating sympatric species of duikers also suggests that dental measurements are not effective for fully diagnosing certain artiodactyl groups. We advocate a systematic revision of Merycoidodontoidea and many other fossil artiodactyl groups with lower emphasis on dental measurements and better accounting for the ways selenodont dentition varies.