Stephanorhinus cf. kirchbergensis Jäger, 1839

Hashemi, N, Ashouri, A, Aliabadian, M, M. Gharaie, M, Sánchez Marco, A & Louys, J, 2016, First report of Quaternary mammals from the Qalehjough area, Lut Desert, Eastern Iran, Palaeontologia Electronica 5 (4), pp. 1-12 : 4

Stephanorhinus cf. kirchbergensis Jäger, 1839

Figure 4.1-2 , Table 1

Material. One right P 4 (but see the text below) (QHJ-45).

Description. This tooth is rectangular in occlusal outline. It is broken anteriorly, and the original shape may be more squared. The lingual margin of the protocone is rounded and bulbously inflated, whereas the buccal side possesses a weak fold. Due to the heavy wear on the tooth, it is separated from the hypocone only by the enamel medial margins of the respective lingual cusps. The metaloph is long, wide, and oblique posteriorly, with a visible small fold in the lingual portion. The complex enamel patterning of the occlusal surface shows that in the crown of the tooth two principal tracts of dentine were present and not filled up by cement. The buccal portion of the ectoloph has a straight margin. A strongly developed crochet curves out at a right angle from the anterior margin of the metaloph and juts buccally before making contact with the lingual margin of the ectoloph. The occlusal surface of the tooth is relatively smooth with a small fracture in the lingual side more than the other sides. In lateral view, it is strongly ectolophodont, with the buccal margin of the tooth significantly higher than the lingual side.

Remarks. Due to its overall dimensions and degree of wear and completeness, this tooth is provisionally identified as a P 4, although it could be a P 3. It is assigned to Stephanorhinus on the basis of its extreme molarisation, presence of a well-developed crochet, bulbous protocone, degree of hypsodonty, and smooth ectoloph. Owing to the lack of other preserved diagnostic characters, it impossible to provide a confident species diagnosis. However, on the basis of its dimensions, the lack of antecrochet, angle between crochet and metaloph ( Lacombat, 2006), as well as its age and geographical location, we consider it comparable to S. kirchbergensis . It is noteworthy that previous palaeontological/archaeological studies conducted in central and western Iran have suggested that most Iranian rhinoceros fossil/subfossil remains belong to Stephanorhinus (see Farshad, 1959; Mashkour et al., 2009), although some of these records may require verification.

Figures

FIGURE 4. Photographs of selected vertebrate fossils from the Qalehjough fossil site. 1-2, a right P4 of Stephanorhinus cf. kirchbergensis (QHJ-45) in lateral (1) and occlusal (2) views. 3-5, three incisors of Equus (QHJ-12–14) in lateral views. 6-7, a right M3 of Equus (QHJ-22) in lateral (6) and occlusal (7) views. 8-9, a left M3 of Equus (QHJ-42) in lateral (8) and occlusal (9) views. 10, a first phalange of Sus (QHJ-37) in lateral view. 11, a left mandible of Ovis aries with P4 (QHJ-44) in lateral view. 12-13, a left M2 of O. aries (QHJ-5) in lateral (12) and occlusal (13) views. 14, a left mandible of Bos (QHJ-1) in lateral view. 15-16, a horn core (mesiodistal part) of Bos (QHJ-26) in internal (15) and external (16) views. 17-18, a left M2 of Gazella (QHJ-23) in lateral (17) and occlusal (18) views. Scale bars equal 1 mm.