Dihoplus schleiermacheri ( Kaup, 1832 )

Montoya, Plinio, Ginsburg, Léonard, Alberdi, María Teresa, Made, Jan Van Der, Morales, Jorge & Soria, María Dolores, 2006, Fossil large mammals from the early Pliocene locality of Alcoy (Spain) and their importance in biostratigraphy, Geodiversitas 28 (1), pp. 137-173 : 137-173

Dihoplus schleiermacheri ( Kaup, 1832) ( Fig. 13 )

MATERIAL EXAMINED. — Right P3; left m2 ( MAA).

2118M, left lower molar ( MGM).

Alc 24, right p3; Alc 25, left p4; Alc 26, right m1; Alc 27, left m1 ( Gervais 1853: pl. IV, fig. 9); Alc 28, right m3; Alc 29, fragment of left m3 ( MNHN).

MEASUREMENTS. — See Appendix: Table 11.

DESCRIPTION

The only upper tooth found is a P3 that lacks its labial part. The protoloph is thin and oriented obliquely backwards. It is joined to the metaloph and closes lingually the anterior valley. The metaloph is thin and curiously semilunar, the back point being joined to the posterior wall. This arrangement is very unusual in the Rhinocerotidae . Apparently it is only known in Dicerorhinus Gloger, 1841 and Dihoplus . This can be seen in Dicerorhinus etruscus (Falconer, 1868) from Sénèze figured by Guérin (1980: pl. 15, fig. C1), the P3 of Dicerorhinus miguelcrusafonti Guérin & Santafé, 1978 from Layna ( Guérin & Santafé 1978: pl. 1, fig. G) and D. schleiermacheri from La Roma ( Cerdeño 1989: fig. 30).

The p3 lacks the posterior part of the second lophid. The metalophid consists of three elements perpendicular to each other; the anterior element is clearly transversal; the larger median one, forms its labial wall. This labial wall is flat and nearly longitudinally oriented. The anterior valley is important. The hypolophid is more curved. The median labial groove is, at the base only, a wide depression that narrows towards the apex to form a real groove.

The p4 differs from the p 3 in its metalophid, with the median part more obliquely oriented and the larger posterior part more obliquely (but backwards) oriented. In the posterior part, the hypolophid consists of three elements: two labial elements that form a very neat angle of 120°, and a third distal one, short and transversely oriented.

The three lower molars are of the same kind. The metalophid is not very different from that of the p4. On the contrary, the hypolophid consists of only two elements. The anterior one is short and longitudinally oriented. The posterior one is twice as long and obliquely oriented. These two elements form an angle of more or less 120°.

REMARKS

All these teeth could belong to the same individual. However the right m3, which is complete, shows insignificant wear of the hypolophid, whereas the fragment of left m3, which is the postero-lingual extremity of the hypolophid, is severely worn. It must be admitted that the left m3 had a growth advance of roughly 9 mm over the right m3.

DISCUSSION

The teeth of the Rhinocerotidae from Alcoy belong to the species D. schleiermacheri , whose type is a complete skull from Eppelsheim (MN9) in rhenish Hesse, described and figured by Kaup in 1832 and 1834. The teeth found, including the peculiar P3, are morphologically identical and the dimensions are within the variation limits of the species as given by Guérin (1980).

The species was at first attributed to the genus Rhinoceros Linnaeus, 1758 . Brandt (1878) established the genus Dihoplus on the base of this species. Zittel (1893) admitted Dihoplus as a subgenus of Rhinoceros , and the name Dihoplus was abandoned. Viret (1955) and Guérin (1980) included the species in the genus Dicerorhinus . Heissig (1999) again used the generic term Dihoplus for the species from Eppelsheim. We will follow this determination since the skull of the current Dicerorhinus sumatrensis (Fischer, 1814) is clearly different from that of Dihoplus schleiermacheri . This latter is lower, more elongate and with a lower occipital part. The zygomatic apophysis is less elevated in the posterior part and the nasal recess is less open in lateral view. In addition, the mandible is also different with a concave and not convex lower edge. Therefore, they are two different genera.

As for what concerns the stratigraphic distribution, Dihoplus schleiermacheri has been found so far in 25 localities (rhenish Germany, Switzerland, France and Spain), all of them considered as Vallesian or Turolian ( Guérin 1980; Cerdeño 1989). The specimen from Venta del Moro ( Morales 1984: fig. 12) is the most similar to that of Alcoy. They have in common the slightly oblique orientation of the median part of the metalophid, which is generally

Early Pliocene mammals from Alcoy ( Spain)

longitudinally oriented. It is interesting to remark that Venta del Moro is placed between the Turolian and the Ruscinian.

Order PROBOSCIDEA Illiger, 1811 Suborder ELEPHANTOIDEA Osborn, 1921

Figures

FIG. 13. — Dihoplus schleiermacheri (Kaup, 1832) from Alcoy: A, right p3 (Alc 24), occlusal view; B, left p4 (Alc 25), occlusal view; C, D, right m1 (Alc 26); C, occlusal view; D, lingual view; E, F, left m1 (Alc 27); E, occlusal view; F, lingual view; G, H, right m3 (Alc 28); G, lingual view; H, occlusal view. Scale bar: 10 mm.