Beck, K.G. & Soler-Gijón, R. & Carlucci, J.R. & Willis, R.E. (2016)
Morphology and histology of dorsal spines of the xenacanthid shark Orthacanthus platypternus from the Lower Permian of Texas, USA: palaeobiological and palaeoenvironmental implications. Acta Palaeontologica Polonica, 61(1), 97–117
DOI: 10.4202/app.00126.2014