Fig. 2. Juvenile Orthacanthus platypternus, Stephanian B in Morphology and histology of dorsal spines of the xenacanthid shark Orthacanthus platypternus from the Lower Permian of Texas, USA: Palaeobiological and palaeoenvironmental implications

Fig. 2. Juvenile Orthacanthus platypternus, Stephanian B (Upper Carboniferous) of Hamilton, USA (A) compared to juvenile of O. bohemicus, Westphalian D (Upper Carboniferous) of Bohemia, Czech Republic (B), showing the relative position of the dorsal spine. A, modified from Zidek (1993b: fig. 1); B, modified from Soler-Gijón (2004: fig. 3C).