Micro-computed tomography images of the skull for the groups of the Chironius bicarinatus complex. Dorsal, lateral, and ventral views of the skulls (A–I) followed by the respective cutaway views (J–R). Chironius bicarinatus: A–C, J–L; C. gouveai: D–F, M–O; and Baturité Massif sample: G–I, P–R. Scale bar = 5 mm. Abbreviations: AN, angular; BO, basioccipital; CB, compound bone; DE, dentary; ECP, ectopterygoid; EO, exoccipital; F, frontal; MA, maxilla; N, nasal; P, parietal; PAL, palatine; PBS, Parabasisphenoid complex; PF, prefrontal; PM, premaxilla; PO, postorbital; PR, prootic; PT, pterygoid; QD, quadrate; SM, septomaxilla; SO, supraoccipital; SP, splenial; ST, supratemporal; VO, vomer.