Hispanodorcas cf. orientalis Bouvrain and Bonis, 1988

Kostopoulos, Dimitris S., 2014, Taxonomic re-assessment and phylogenetic relationships of Miocene homonymously spiral-horned antelopes, Acta Palaeontologica Polonica 59 (1), pp. 9-29 : 12-13

Hispanodorcas cf. orientalis Bouvrain and Bonis, 1988

Fig. 3 .

1996 Oioceros cf. atropatenes (partim); Kostopoulos and Koufos 1996: 279, pl. 4.

1996? Gazella sp. ; Kostopoulos and Koufos1996: 278, pl. 3: e, f.

Material.—Partial braincase with left horncore, LGPUT NKT−227; frontlet, LGPUT NKT−118, 228; proximal part of right horncore, LGPUT NKT−231; distal part of left horncore, LGPUT NKT−232; part of left mandibular ramus with p3–m3, LGPUT NKT−250. All specimens are from the primate−bearing locality of Nikiti−1, located in the upper part of the Nikiti Formation (Vallesian, MN10; Koufos 2006) exposed on the Chalkidiki Peninsula, northern Greece ( Koufos et al. 1991).

Description.—The width of the braincase ( LGPUT NKT−227; Fig. 3B ) behind the horncores is 57.6 mm, very similar to that of the holotype of H. orientalis (56.9 mm). The frontals are strongly flexed between the horncores ( Fig. 3B ), indicating either that the face was significantly inclined compared to the braincase (but less so than in H. orientalis ; Bouvrain and Bonis 1988: 101), or that the area between the nasals and the pedicles was strongly depressed, as also seen in Oioceros (e.g., Roussiakis 2003). The postcornual fossa of the Nikiti−1 taxon varies in size and is positioned laterally, as in H. orientalis . The homonymously twisted horncores are inserted above the orbits, located far apart from each other, weakly inclined, and curved backwards ( Fig. 3B ). While being almost parallel at the base, they are strongly divergent distally. In cross section, the horncore is elliptical to semicircular in outline, and strongly compressed transversely ( Fig. 1 ), with the greater basal axis forming a moderately large angle with the sagittal plane. The medial surface of the proximal horncore is strongly convex, whereas the lateral surface is flattened, but barely depressed ( Fig. 3A ). However, towards the tip, the flattened lateral surface gives rise to a deep furrow dividing the horncore into a thin and long anterior and a wide and short posterior part ( LGPUT NKT−232; Fig. 3C ). A narrow groove opening towards (but not extending on to) the pedicle is present on the proximal lateral surface of some specimens ( LGPUT NKT−118, 228). A moderately developed, anteromedially descending anterior keel occurs in LGPUT NKT−231 and 227, while a deep posterior furrow appears in LGPUT NKT−232, thus resembling both H. torrubiae and H. orientalis .

The length of the lower molar row is 34.3 mm. The lower molars lack goat folds, and a strong parastylid and well−defined metastylid occur on m2 and m3. The ribs of the metaconid and the entoconid are well developed lingually. A basal pillar is present only on m1. On p4, the parastylid is weakly separated from the paraconid, while the metaconid curves distally and fuses with the posterior stylid (entoconid + entostylid). On p3, the metaconid is directed posteriorly, but otherwise p3 is similar to p4.

Remarks.— Kostopoulos and Koufos (1996) mistakenly referred the material from Nikiti−1 to? Gazella sp. or Oioceros cf. atropatenes . It is now evident that the specimens from Nikiti−1 represent Hispanodorcas , even though some additional dental material from the same site ( LGPUT NKT229, 230, 102; Kostopoulos and Koufos 1996: 29) belongs to another, slightly larger, as yet unidentified bovid. Apart from some minor morphological differences, which may be attributed to its older age, the Nikiti− 1 specimen of Hispanodorcas is strikingly similar to H. orientalis from Dytiko−3.

Figures

Fig. 3. Oiocerin antelope Hispanodorcas cf. orientalis Bouvrain and Bonis, 1988 from Nikiti−1 (NKT), Chalkidiki Peninsula, Northern Greece, latest Vallesian. A. LGPUT NKT−231, lateral view of the right basal horncore. B. LGPUT NKT−227, left lateral (B1) and anterior (B2) views of the frontlet. C. LGPUT NKT−232, lateral view of the left distal horncore. The arrow indicates the distal end of the lateral depression and marks the distal “bilobation” of the lateral side of the horncore.

Fig. 1. Box−plots of the horncore basal compression index (i.e., TD*100/ ADP) for several species and genera of Oiocerina, showing the medial (horizontal line inside the boxes), the 25–75% quartiles (gray boxes) and the minimum and maximum range of values (short horizontal lines). NKT−1, Nikiti−1; RZ1, Ravin des Zouaves 1.