Table 2. Categorical characters of the morphological traits of ossicles used in the clustering analysis.

Lateral teeth		Medial tooth		Accessory teeth		Cardiopyloric valve
(1) Surface of the lateral teeth	0-Flattened cusps 1-Incisor cusps 2-Sharp cusps	(3) Shape of medial tooth	0-Posterior process without transverse ridges 1-With less than two transverse ridges 2-With at least three pronounced transverse ridges	(5) Shape of the accessory teeth	0-Vestigial 1-More than 1 softly cuspidate tooth	(7) Ventro-lateral surface	0-W-shaped 1-Smooth
(2) Hollow between ventral and dorsal cusps	0-Absence 1-Presence	(4) Margen ventro-lateral	0-Absence of lateral cusps anterior to the medial tooth 1-Presence of lateral cusps anterior to the medial tooth	(6) Disposal of denticles of the lateral tooth	0-In a row 1-In a semicircle 2-With a single tooth