Fig. 4 in The Braincase In Paleozoic Symmoriiform And Cladoselachian Sharks

Fig. 4. Left lateral views of the mandibular musculature in four modern dalatiiform sharks to show variation in the origin and extent of the preorbital (suborbital) muscle. A, Etmopterus spinax; B, Centroscyllium excelsum (preorbital muscle originates above ventral keel process in A and B); C, Trigonognathus kabeyai (preorbital muscle absent); D, Squaliolus laticaudus (preorbital muscle originates on interorbital septum). After shirai (1992), Shirai and Okamura (1992). Scale bar 5 10 mm.