Fig. 4 in Significance of intermediate forms in phyletic reconstruction of ammonites: Early Jurassic Phricodoceras case study

Fig. 4. Position and terminology of the tubercles, spines and/or bullae on Phricodoceras shells (juvenile and/or microconch. A, B. Normal view. C, D. Shaded view with indication of the main ornamental structure outlines (white lines). Abbreviations: t1, latero−umbilical position; t2, latero−ventral position; t3, peri−siphonal position; us, umbilical seam; vb, ventral band.