Boxplot showing the distribution of the ratio between the length and the width at mid-shaft of metacarpal III for
a sample of iguanodontoidean ornithopods. The inserted smaller graph shows the Bayesian information criterion (BIC) for various numbers of
clusters in which the data can be classified. The photograph shows how the two variable of this ratio were measured, exemplified in a
metacarpal III of Tsintaosaurus spinorhinus (IVPP V725). Grey horizontal lines delimit character states.