Morphological descriptors of I elements of Icriodus alternatus. A. “Small” specimen (UM BUS 031), upper (occlusal) view. 2D counts: Number of triads (Triads_nb): estimation of the number of triads, based on the presence of the pair of outer and inner denticles; Number of median denticles on the spindle area (Med_dent_nb); Number of lateral denticle on the blade area (Lat_blade_dent); Number of median denticle on the blade area (Med_blade_dent). B. Icriodus alternatus helmsi (UM BUS 035), upper (occlusal) view. Biometric measurements (D1, MaxLength, MaxWidth, area and spindle area). Triads in yellow; spindle area in blue dotted line, area of the 2D specimen in red, D1 distance between the inner and the outer denticles of the first triad in orange. C. Icriodus alternatus alternatus (UM BUS 033), upper and lower views (not to scale) with the position of the 3D landmarks (3D measurements). In green the valleys; in yellow the denticles.