Boxplot showing the distribution of the length of the ulna relative to its dorsoventral thickness (measured
at mid-shaft) 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 ulna of Parasaurolopus walkeri (ROM 768). Grey horizontal lines delimit character states.