Ronzotherium Aymard, 1854

Tissier, Jérémy, Antoine, Pierre-Olivier & Becker, Damien, 2021, New species, revision, and phylogeny of Ronzotherium Aymard, 1854 (Perissodactyla, Rhinocerotidae), European Journal of Taxonomy 753, pp. 1-80 : 10

Genus Ronzotherium Aymard, 1854

Type species

Ronzotherium velaunum (Aymard in Pictet, 1853)

Other species

Ronzotherium filholi ( Osborn, 1900) ; Ronzotherium romani Kretzoi, 1940 ; Ronzotherium elongatum Heissig, 1969 ; Ronzotherium heissigi sp. nov.

Emended diagnosis

These are large-sized hornless rhinocerotoids with two pointed upper incisors (I1 and I2) but only one large tusk-shaped lower incisor (i2) and without canines. The crown of the i1 is reduced. The dorsal profile of the skull is concave. The nasal incision is short and opening above P1–3. The anterior border of the orbit is above the molars and the infraorbital foramen is above P3–4. The processus posttympanicus and paraoccipitalis are fused at their base. The upper premolars are not molarised and the hypocone is always connected or completely fused to the protocone on P3–4. The upper molars are simple, with poorly developed crochet and antecrochet and the crista is always absent. The posterior part of the ectoloph of the upper molars is straight. The M3 is quadrangular in occlusal view. The ectoloph and metaloph are fused into an ectometaloph on M3, and there is no metastyle, but a posterior groove remains. The entoconid is very poorly developed on the lower premolars, or completely absent, and the opening of the posterior valley is wide and U-shaped. The lower d1 is usually absent. The ectolophid groove of the lower molars is developed until the neck. The distal articulation of the pyramidal for the lunate is symmetrical in medial view, the indentation on the medial side of the magnum is absent and the posterior tuberosity of the magnum is short. The collum tali of the astragalus is high.

Stratigraphical distribution

Late Eocene (?) to latest Oligocene.

Geographical distribution

Europe.