Fig. 4

Morphological evidence for flatfish monophyly is not restricted to cranial asymmetry, but is instead widely distributed in both hard-tissue and soft-tissue anatomy. a inverted radiograph of Lates calcarifer (Natural History Museum, London [NHMUK] 5.85), a carangimorph retaining many generalized percomorph features. b inverted radiograph of Psettodes erumei (NHMUK 1931.4.23.2), a member of Psettodoidei. c inverted radiograph of Paralichthys albigutta (NHMUK 1989.9.22.78-81), a member of Pleuronectoidei. Proposed pleuronectiform synapomorphies related to cranial asymmetry indicated in grey: 1, orbital migration; 2*, recessus orbitalis; 3, pseudomesial bar; 4*, asymmetrical pigmentation. Proposed pleuronectiform synapomorphies not related to cranial asummetry indicated in black: 5*, circumsulcal depression on inner face of saccular otolith; 6, dorsal-fin insertion above skull; 7, absence of supraneurals; 8, absence of membranous extensions on shafts of most dorsal- and anal-fin proximal-middle radials; 9*, epaxial muscle insertions on dorsal-fin proximal-middle radials comprising bundles of muscle that pass underneath the depressors dorsales; 10, haemal arch and spine of third preural vertebra fused to the centrum; 11, full neural spine on the second preural centrum; 12, two or fewer epurals; 13, absence of procurrent spur; 14*, partial or complete fusion between the dorsal fin longitudinal ramus and the dorsal longitudinal collector nerve of the trunk lateral line nervous system. Characters marked with an asterisk (‘*’) indicate soft-tissue features not apparent in radiographs. See references [26, 28, 71, 86, 87] for a discussion of proposed synapomorphies. Scalebars represent 10 mm