Boxplot showing the distribution of the the ratio between the minimum mediolateral width of the rostral
constriction and the maximum width of the basisphenoid across the spheno-occipital tubercles 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 variables of this raio were measured, exemplified in the parietal of Edmontosaurus sp. (AMNH 427).
Grey horizontal lines delimit character states.