Ronzotherium velaunum
Creators: name: Tissier, Jérémy
name: Antoine, Pierre-Olivier
name: Becker, Damien
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Perissodactyla
Rhinocerotidae
Ronzotherium
Ronzotherium velaunum

description: Ronzotherium velaunum (Aymard in Pictet, 1853)
Figs 2–7
Acerotherium velaunum Aymard in Pictet, 1853: 296.
Ronzotherium cuvieri Aymard, 1856: 233.
Rhinoceros velaunus – Aymard in Pictet 1853: 298.
Rhinocéros à incisives (Ronzotherium) – Aymard 1854: 675.
Ronzotherium velaunum – Aymard 1856: 233. — Filhol 1881: 3. — Osborn 1900: 232–237, 241, fig. 3. — Deninger 1903: 94–95. — Stehlin 1909: 509. — Abel 1910: 4–6, 8–9, 18, 33. — Roman 1912a: 4–5, 8, 10. — Kafka 1913: 5, 47, fig. 40a. — Airaghi1925: 25. — Heissig 1969: figs 6a, 8c, 9a, 10a, 11, 25a (from Ronzon). — Brunet 1977: 16, 23; 1979: 102–104, 152–153, table 51, pls XV, XIXa–f. — Brunet et al. 1977: 109–112. — Jehenne & Brunet 1992: 202–203. — Uhlig 1996: 140–142. — Ménouret & Guérin 2009: 293–327. — Becker 2009: 495, 500.
Ronzotherium cuvieri (?) – Filhol 1881: 3.
Acerotherium velaunum – Filhol 1881: 75–78, figs 69–86, 88. — Mermier 1895: 176, 180, 186. — Roman 1910: 1558–1560; 1912a: 7, 27, 42–45, 56, 78, fig. 13, pl. II figs 2, 2a. — Gignoux 1928: 147, 149, 151.
Acerotherium cuvieri – Filhol 1881: fig. 87, 89–90. — Airaghi 1925: 26, 29.
? Ronzotherium cf. velaunum – Schlossser 1902: 112–113, pl. V figs 23, 25.
Rhinoceros velaunus – Roman 1912a: 45.
? Ronzotherium velaunum – Kafka 1913: 48–50, figs 40b, 41. — Kretzoi 1940: 89–92, 97–98, figs 1–2. — Lavocat 1951: 115. — Balme 2000: 153. — Costeur & Guérin 2001: 77.
Rhinoceros velaunum – Airaghi 1925: 32–33, 40–41.
Ronzotherium cf. velaunum – Heissig 1978: 249.
Non Ronzotherium filholi – Lavocat 1951: 116, pl. 19 fig. 3, pl. 26 fig. 1 (from Vendèze).
Non Ronzotherium velaunum – Heissig 1969: figs 5, 6b–d, 7, 8a–b, d–g, 9b–c, 10b–d, 25b (from ‘Auvergne’, Mouillac, Vendèze, St-Henri, St-André, Marseille, Les Milles).
Historical diagnoses
The first diagnosis of the species was provided by Heissig (1969, translated by the authors): “ type species of the genus Ronzotherium with almost parallel i2 facing forward; i1 absent, I1 and I2 large. Lower jaw branches at an acute angle to each other. Upper molars broad, with long postfossette, narrow, slightly curved medisinus, thick and far forward paracone and mostly weak or missing lingual cingulum; M3 with sharp, narrow ectoloph edge behind the metacone. Upper premolars with straight or barely curved, parallel, originally slightly inclined transverse lophs and strongly waved lingual cingulum, slowly reduced; reduction begins at P4. P2 semimolariform to molariform, P3 and P4 premolariform to submolariform, but with relatively far apart inner lophs. Lower molars broad with weak labial cingulum; lower premolars with long talonid, mostly groove-shaped talonid pit and sharp, deep external groove. The entoconid lies far back, the cingulum is weak. The p1 is single rooted or missing.”
An emended diagnosis was provided by Brunet (1979, translated by the authors): “Stratigraphically the most ancient and primitive species of its kind. Skull: unknown. Mandible: posterior border of the symphysis just ahead of the d1, its lower surface presents a hull; very strong occlusion between i1 and i2. Decidual teeth: the upper milk premolars are unknown; the inferiors have a strongly curved hypolophid; d1 is biradiculate; the first lobe of d2 is strong with a long lingual branch of the paralophid, the ‘metaconid’ is not individualized; the anterior lobe of d3 is strong with a very long anterior branch of the paralophid. Definitive dentition: probable presence of i1. Upper premolars with a short postfossette, located above the posterior cingulum; strong lingual cingulum, barely waved. Upper molars with strong lingual cingulum, complete or disappearing only at the level of the hypocone. Lower premolars and molars: more or less large with a strong labial cingulum, more or less complete; the very notched talonid fossae on the labial side of the hypolophid are flatter, more horizontal, and lingually higher than in R. filholi; the trigonid fossae also open higher, above the anterolingual cingulum; premolars with long paralophid, without protoconid fold; P2 not reduced, with a strong anterolabial groove. Appendicular skeleton: tetradactyl hand with a gracile McV, reduced but complete; on the dorsal side of the hand, the lunate articulates with the magnum; on the pyramidal, the ulnar facet is more laterally widened and the lower facet for the lunate higher and larger than in R. filholi; likewise, the magnum carries a much longer and higher facet for the McII.”
Emended diagnosis
Type species of the genus with a posterior border of the symphysis located anterior to p2 and without lingual groove for the sulcus mylohyoideus on the corpus mandibulae. The metacone fold is present on M1–2. The d1 is absent in the juvenile, and the entoconid is constricted on decidual lower milk teeth. The cingula are poorly developed on upper and lower cheek teeth and discontinuous. The posteroproximal and anteroproximal facets for the lunate are in contact on the scaphoid and the fibula facet is oblique on the astragalus. The trapezium facet is absent on the McII.
Type material
Lectotype
FRANCE • right hemimandible still partly in sediment with poorly preserved p2–m3 and broken symphysis; Haute-Loire, near Le Puy-en-Velay, hill of Ronzon; PUY.2004.6.1765.RON.
Additional material
FRANCE • 1 broken mandible in several pieces, with i2 and p2–m3 on the left side and i2 and p2–(m1) on the right side; same collection data as for lectotype; PUY.2004.6.1766.RON • 1 juvenile mandible, still partly in sediment, with d2–d4 and erupting m1 on both sides and a small di1; same collection data as for lectotype; PUY.2004.7.1.RON • 1 broken ectoloph of P2?; same collection data as for lectotype; PUY.2004.6.1551.RON • 1 isolated P3; same collection data as for lectotype; PUY.2004.6.1767.RON • 1 isolated M1; same collection data as for lectotype; TLM.PAL.2010.0.122 • 1 cast of an isolated lower molar; same collection data as for lectotype; PUY.2004.6.841.RON • 1 distal part of humerus; same collection data as for lectotype; PUY.2004.6.262.RON • 1 complete scaphoid; same collection data as for lectotype; MNHN.F.RZN.503 • 1 lunate partly unextracted from sediment; same collection data as for lectotype; PUY.2004.6.1901.RON • 1 pyramidal, still in sediment; same collection data as for lectotype; MNHN.F.RZN.504 • 1 pyramidal; same collection data as for lectotype; MNHN.F.RZN.502 • 1 pisiforms, still in sediment; same collection data as for lectotype; MNHN.F.RZN.505 • 1 pisiforms, still in sediment; same collection data as for lectotype; PUY.2004.6.1901.RON • 1 magnum, still in sediment; same collection data as for lectotype; PUY.2004.6.907.RON • 1 magnum; same collection data as for lectotype; PUY.2004.6.263.RON • 1 broken anterior part of unciform; same collection data as for lectotype; PUY.2004.6.1480.RON • 2 distal parts of femora; same collection data as for lectotype; PUY.2004.6.266.RON, PUY.2004.6.267.RON • 2 proximal parts of tibiae; same collection data as for lectotype; PUY.2004.6.260.RON, PUY.2004.6.261.RON • 1 ectocuneiform, still partly in sediment; same collection data as for lectotype; PUY.2004.6.577.RON • 1 cuboid, still in sediment; same collection data as for lectotype; PUY.2004.6.1309.RON • 1 cuboid; same collection data as for lectotype; PUY.2004.6.268.RON • 1 astragalus, still preserved in sediment; same collection data as for lectotype; PUY.2004.6.1770.RON • 1 central metapodial, still in sediment; same collection data as for lectotype; PUY.2004.6.840.RON • 1 lateral phalanx, still in sediment; same collection data as for lectotype; PUY.2004.6.604.RON.
Type horizon and locality
Hill of Ronzon, near Le Puy-en-Velay (Haute-Loire, France), MP21 (early Oligocene).
Stratigraphical distribution
MP21 (early Oligocene).
Geographical distribution
France: Ronzon, Lagny-Torigny, Ruch. Germany: Haag 2, Möhren 20.
Description
MANDIBLES. Three mandibles of R. velaunum from Ronzon are preserved. The lectotype mandible PUY.2004.6.1765.RON is a right hemimandible with p2–m3 (Fig. 2A–D). The posterior part of the specimen and the symphysis are broken, and the left side is still in sediment. The base of the corpus mandibulae is straight and low, with a constant height below the teeth neck. The ramus is vertical, and the coronoid process is well developed and high. The mandible PUY.2004.6.1766.RON is badly preserved and in several pieces (Fig. 2E–J). The symphysis as well as both branches are preserved, with i2, the root of d1 and p2–m3 on the left side, and only i2 and p2–m1 on the right side. It was recently prepared and new characters can now be observed: the angle between the symphysis and the corpus is low, the symphysis is rather narrow and its posterior borders is in front of p2, the foramen mentale is below p2 and there is no lingual groove of the sulcus mylohyoideus. The last mandible PUY. 2004.7.1.RON belonged to a juvenile individual and is still partly preserved in sediment (Fig. 2K–O). It bears d2–d4 and erupting m1 on both sides as well as a small di1 on the right side. There is apparently no dp1. The posterior border of the symphysis is anterior to d2. No lingual groove of the sulcus mylohyoideus is visible.
UPPER DENTITION. Very few upper teeth are preserved in this locality (Fig. 3): an ectoloph of a left P2 (PUY.2004.6.1551.RON), a P3 (PUY.2004.6.1767.RON) and an M1 (TLM.PAL.2010.0.122). However, Filhol (1881) noted the existence of an upper maxilla that he could not have accessed during his study and was supposedly in Pichot-Dumazel’s collection. Unfortunately, this maxilla remains unknown. The P2 and P3 have strong paracone and metacone folds and very thin discontinuous labial cingulum. Their crown is low. The lingual cingulum is strong and continuous on P3. The P3 is three-rooted and few characters can be observed, as it is very worn. Its postfossette is narrow and the protocone and hypocone were probably not separated. The M1 has four roots and is also much worn. Labial cingulum is almost completely absent. Lingual cingulum is strong and continuous under the protocone and disappears under the hypocone. The paracone fold is strong and the metacone fold is present but very thin. The parastyle is strong and there is no mesostyle. The protocone does not seem constricted. The posterior profile of the ectoloph is slightly concave.
LOWER DENTITION. The definitive anterior dentition is only represented by two i2 from the mandible PUY.2004.6.1766.RON. They are straight and horizontal. The roots are wider than the crown, and the crown shows a clear and large wear-facet, which means that I1 and i2 could contact each other. The transverse outline of the crown is in the shape of a medially pinched drop. The neck is not marked and the enamel is very thin. The lower cheek teeth are two-rooted and low-crowned. There is no cement. The premolar row is short compared to the molar row (0.42 <Lp3–4/Lm1–3 <0.50). A weak labial cingulum is sometimes present on the lower cheek teeth, but a lingual cingulum is always absent. Vertical external rugosities are present on the ectolophid of p2–3. The ectolophid groove is developed and does not vanish before the neck. In occlusal view, the trigonid is very angular and forms a right dihedron which becomes more acute with wear, while the talonid is rounded. The talonid basin of the lower premolars is poorly developed: the entoconid is completely absent and the hypoconid is low. The hypolophid vanishes before the posterolingual border of the premolars, the posterior valley is therefore very wide and U-shaped. On the contrary, the anterior valley is narrow, and both valleys open very high above the neck. The metaconid is the largest and most developed cusp on lower premolars. On p3, the metaconid bears an anterior crest, almost closing the anterior valley. The paralophid of premolars has two branches, a labial branch, and a high and long anterior branch, parallel to the protolophid. The molars greatly differ from the premolars by the much stronger development of the entoconid, which is also slightly constricted. The opening of the anterior valley is higher than the posterior one.
DECIDUAL DENTITION. Only the lower decidual dentition is known from Ronzon, from the juvenile mandible PUY. 2004.7.1.RON (Fig. 2K–O). The di1 is very small and has a conical crown. There does not seem to be a d 1 in the juveniles. However, d2–4 are well developed. The metaconid and entoconid are slightly constricted, especially on d4. There is neither a protoconid fold nor a vertical external rugosity. The lingual and labial cingulum are absent. The ectolophid fold is strong on d2 but there is no anterior groove on the ectolophid. The paralophid is double on d2–3 and simple on d4. On d2, the posterior valley is almost closed by the extension of the entoconid, but still narrowly open. There is no lingual groove of the entoconid on d3. The d4 is very molariform.
HUMERUS. One distal fragment of humerus is preserved (PUY.2004.6.262.RON, Fig. 4A–C). The fossa olecrani is high but not very deep. The distal articulation is well constricted and there is no scar on the trochlea. The distal gutter on the epicondyle is also absent. Medial and lateral epicondyles are poorly developed and the lateral epicondylar crest is weakly extended laterally.
SCAPHOID. The scaphoid MNHN.F.RZN.503 (Fig. 4D–G) is well preserved. The anterior height is equal to the posterior one. The postero-proximal articulation with the lunate bone is not visible but may have been present on the eroded proximo-lateral tuberosity and fused with the anteroproximal facet. The proximal facet for the radius is very concave and fuses anteriorly with the anteroproximal facet for the lunate bone. The anterodistal facet for the lunate is poorly distinguished. The three distal articular facets are concave in lateral view. The trapezium facet is rather large and triangular. The trapezoid facet is the largest and has a prominent dorso-medial extension. The magnum facet is concave in lateral view.
LUNATE. The lunate bone PUY.2004.6.1901.RON (Fig. 4H–J) is still mostly concealed in the sedimentary block. Only the proximal, dorsal and lateral sides are visible. It is an overall large and robust bone. The posterior tuberosity is almost as wide as the proximal facet for the radius. Two articular facets are visible on the lateral side, both corresponding to the pyramidal bone. The proximal facet is small while the distal one is large, flat and circular. On the medial side, two well separated articular facets can be distinguished and correspond to the scaphoid, which implies the presence of a postero-proximal facet for the lunate on the scaphoid, that is not visible on the scaphoid MNHN.F.RZN.503.
PYRAMIDAL. Two pyramidals are preserved (MNHN.F.RZN.502, Fig. 4K–M and MNHN.RZN.504, Fig. 4N). There are two proximal articulation facets: a large one for the ulna, and a smaller one, elongated and band-like for the pisiform. The medio-distal articulation for the lunate is symmetrical and the distal facet for the unciform is triangular.
PISIFORM. The pisiform MNHN.RZN.505 is still in articulation with the pyramidal MNHN.RZN.504. Another unnumbered pisiform is preserved on the sedimentary bloc of the lunate bone PUY.2004.6.1901. RON. The pisiform is very small, and neither flattened nor elongated. It bears a large proximal articular facet for the radius. The distal end is roughly conical and rounded.
UNCIFORM. Only the dorsal part of the left unciform PUY.2004.6.1480.RON is preserved, the posterior tuberosity is missing (Fig. 5F–G). There are two proximal facets: a large one, dorso-ventrally convex for the pyramidal, and smaller one, flattened and arrowhead-shaped for the lunate. They form an angle of 120–130° in dorsal view. The posterior expansion of the pyramidal facet is very short and wide. The three distal facets, for the magnum, McIII and McIV, are partially covered in sediment. The lateral McV facet is broken but was probably distinct from the pyramidal facet.
MAGNUM. Two magnums are preserved. PUY.2004.6.907.RON is still in a sedimentary bloc, while PUY.2004.6.263.RON is subcomplete and fully extracted (Fig. 5A–E). It is a rather tall bone, the proximodistal height is almost equal to the dorsoventral length, but it is very compressed transversally. In anterior view, the anterior border of the scaphoid facet is nearly straight. The lunate facet is very long dorsoventrally, and very convex proximally. There are two medial facets below the scaphoid facet: a proximal one for the trapezoid and a distal one for the McII. The former is trapezoidal while the latter is curved. There is no indentation between these two facets. The distal facet for the McIII is large and deeply concave dorsoventrally. The unciform facet on the lateral side is not preserved. The posterior tuberosity of the magnum is long, thin and curved.
FEMUR. There are two distal ends of left femora in Ronzon (PUY.2004.6.266.RON, Fig. 6A–D, I and PUY.2004.6.267.RON, Fig. 6E–H, J). In anterior view, the medial lip of the trochlea is prominent. The groove between the two trochlea is not very deep and the proximal border of the trochlea is almost straight. In lateral view, the medial lip of the trochlea is strongly forward compared to the diaphysis. In posterior view, the two condyles are similar in size and widely separated by the intercondylar fossa.
The supracondylar fossa is shallow. In distal view, the articular surfaces of the trochlea and the condyles are connected medially and laterally.
TIBIA. Two proximal ends of left tibias (PUY.2004.6.260.RON and PUY.2004.6.261.RON) could belong to the same individuals as the femora (Fig. 6K–P). In proximal view, it is wider than long. The tibial tuberosity is weakly developed and is laterally displaced. It is separated from the medial tuberosity by a wide groove. The cranial intercondylar area is deep and wide, the central one very small and the caudal one is deep and slender. The lateral condyle is oval, and wider than long, while the medial one is almost rectangular and longer than wide. In anterior view, the medial tuberosity is higher than the lateral one. In lateral view, the groove for the extensor is wide and shallow and the tibial fossa rather deep. The tibia and fibula were completely independent, there is no contact mark along the diaphysis, only a high articular facet below the lateral condyle.
ASTRAGALUS. Only the anterior face of the astragalus (PUY.2004.6.1770.RON) is visible, the other side is still in sediment, but it is complete (Fig. 7A–D). The transverse diameter/height (TD/H) ratio is slightly above 1, but below 1.2, whereas the anteroposterior diameter/height (APD/H) ratio is below 0.65. On the lateral side, the fibula facet is slightly oblique and flat. The collum tali is very high. There are two distal articular facets: the navicular facet is large and slightly concave transversally, while the facet for the cuboid is small and flat. In distal view, the trochlea is very oblique compared to the distal articulation. The medio distal tubercle is well developed.
CUBOID. Two cuboids are preserved: one is still partially in sediment (PUY.2004.6.1309.RON) but the other is subcomplete (PUY.2004.6.268.RON, Fig. 7I–M). The proximal articular surface is triangular. There are two distinct surfaces, for the astragalus and the calcaneus, distinguished by a shallow groove. The calcanear one is the largest. In anterior view, the bone is rectangular and higher than wide. In lateral view, the lateral groove for the tendons is very deep. The posterior apophysis is wide and stout, and extends more distally than the distal articular facet. The distal articulation surface for the MtIV is almost a right triangle with rounded edges.
ECTOCUNEIFORM. The right ectocuneiform PUY.2004.6.577.RON is still partially in sediment, the proximal side is not visible (Fig. 7E–H). The distal articular facet for the MtIII is crescent-shaped. The posterolateral process is rather short and medially oriented. The medial side is straight and bears three facets: one dorsal and band-shaped for the mesocuneiform, and two distal, oval-shaped for the MtII. The lateral side is curved and the two articulations postero-proximal and anterodistal for the cuboid are separated by a deep groove.
METAPODIAL. A central metapodial (PUY.2004.6.840.RON) is also preserved from Ronzon, still in sediment, and only the dorsal side is visible (Fig. 5H–I). The proximal articulation is very incomplete, but it is nonetheless rather dorsoventrally flat, which would indicate a MtIII rather than a McIII, as also suggested by Brunet (1979). There is a small anteroproximal facet for the MtII, the posterior one, if present is hidden by sediment. The diaphysis gets slightly wider towards the distal end. The median keel of the distal articulation is smooth.
LOST MATERIAL. The scaphoid and pyramidal thought as lost by Brunet(1979) and figured by Filhol (1881) are now in fact in the collections of MNHN (Paris, France) (MNHN.F.RZN.502, MNHN.F.RZN.503 and MNHN.F.RZN.504). However, the calcaneum, MtIV and McV, figured by Filhol (1881: pl. 13), are indeed lost and could not be found either in the Musée Crozatier (Le Puy-en-Velay, France) or in the MNHN.
description: Published as part of Tissier, Jérémy, Antoine, Pierre-Olivier & Becker, Damien, 2021, New species, revision, and phylogeny of Ronzotherium Aymard, 1854 (Perissodactyla, Rhinocerotidae), pp. 1-80 in European Journal of Taxonomy 753 on pages 10-19, DOI: 10.5852/ejt.2021.753.1389, http://zenodo.org/record/4945875