Bos sauveli Urbain, 1937

Suraprasit, Kantapon, Jaeger, Jean-Jacques, Chaimanee, Yaowalak, Chavasseau, Olivier, Yamee, Chotima, Tian, Pannipa & Panha, Somsak, 2016, The Middle Pleistocene vertebrate fauna from Khok Sung (Nakhon Ratchasima, Thailand): biochronological and paleobiogeographical implications, ZooKeys 613, pp. 1-157 : 40-43

Taxon classification Animalia Artiodactyla Bovidae

Bos sauveli Urbain, 1937

Referred material.

A left DP3, DMR-KS-05-03-29-8; a left P3, DMR-KS-05-04-01-4; a left fragmentary M1 or M2 (posterior portion), DMR-KS-05-03-23-2; a right M3, DMR-KS-05-03-29-6; a right mandible with m1-m3, DMR-KS-05-03-9-1; two left mandibles-DMR-KS-05-04-9-1 (with p2, p4, and m1-m3) and DMR-KS-05-04-29-1 (with m3); a left i2, DMR-KS-05-03-15-12; a right i3, DMR-KS-05-03-23-4; a right p2, DMR-KS-05-04-01-6; a right m1, DMR-KS-05-03-15-10; a right m2, DMR-KS-05-03-29-7; two m3-DMR-KS-05-04-28-4 (right broken posterior lobe) and DMR-KS-05-03-24-5 (left); a left humerus, DMR-KS-05-03-20-2(1).

Material description.

Upper dentition: DP3 (DMR-KS-05-03-29-8) is molariform and elongated, characterized by well-developed anterior and posterior cingula, buccal styles, and medial fossettes, a slightly-developed entostyle, and a reduction of the anterior lobe width and height compared to the posterior lobe (Fig. 25A). The P3 (DMR-KS-05-04-01-4) has distinct styles (particularly the metastyle), protocone, and hypocone and an irregular fossette. (Fig. 25B). Upper molars have a rectangular outline and distinct styles, entostyles, and single medial fossettes with wear (Fig. 25C, E) (for measurements, see Tab. 15). The infundibula are X- or metacentric chromosome-shaped on the moderately worn molars (Fig. 25C, E). The entostyles (column) of DMR-KS-05-03-23-2 (M1 or M2: Fig. 25C, D) and DMR-KS-05-03-29-6 (M3: Fig. 25E) are often bifurcated and lingually flat in occlusal view. A distinct longitudi nal groove runs along the lingual surface of the entostyle (Fig. 25D). The M3 is more rectangular in outline compared to other upper molars. The posterior lobe of the M3 is relatively reduced in width and the fossettes are large (Fig. 25E).

Mandible and lower dentition: two mandibles, DMR-KS-05-03-9-1 (Fig. 25H, I) and DMR-KS-05-04-9-1 (Fig. 25J, K), are almost complete (for measurements, see Appendix 13). All incisors and premolars dropped out of the first specimen. The second specimen lacks all incisors and the p3. Another fragmentary mandible DMR-KS-05-04-29-1 preserves only a posterior lobe of the m3.

The i2 (DMR-KS-05-03-22-15) and i3 (DMR-KS-05-03-23-4) are spatulate and small, compared to other species of Bos (for measurements, see Tab. 15). The two p2 (DMR-KS-05-04-9-1: Fig. 25H and DMR-KS-05-04-01-6: Fig. 25F) is small and shows a protruding preprotoconulidcristid and a fusion between the postentocristid and the posthypocristid. The p4 displays well-developed conids and cristids. The postprotocristid is large, compared to other Bos species. On the lower molars, the metastylid is poorly-developed, but becoming more prominent in m3 (Fig. 25H). The anterior and posterior fossettes is metacentric chromosome-shaped with wear (Fig. 25H, J). The posterior talonid of the m3 is well-developed (Fig. 25H, J). The posthypoconulidcristid protrudes posteriorly and sometimes bifurcates into two flanges, as observed on the specimen DMR-KS-05-04-9-1 (Fig. 25H). The entostylid slightly protrudes lingually in relation to heavy wear and the posterior ectostylid is usually absent.

Postcranial remains: a humerus, DMR-KS-05-03-20-2(1), preserves the shaft and distal part (Fig. L–N). We attribute this humerus to Bos sauveli according to the proportional correlation with the extant specimens (Tab. 13 and Appendix 7). This specimen is also smaller than that of extant Bos javanicus and Bos gaurus (Appendices 1 and 7).

Taxonomic remarks and comparisons.

Southeast Asian large bovids are accurately identified by differences in cranial features (especially horn cores), although they show sexual and ontogenetic variation in morphology. Lacking the cranial remains, it is difficult to make a distinction within the species of Bos . Due to the lack of cranial remains of koupreys ( Bos sauveli ) collected from Khok Sung, we identify these fossils on the basis of dental features.

Based on our comparisons with some extant specimens (MNHN-ZMO-1940-51 and MNHN-ZMO-10801), the cheek teeth of koupreys are similar to those of other species of Bos , characterized by having hypsodont crowns, well-developed styles and stylids, a horse shoe-shaped infundibulum (anterior and posterior fossettes), and bifurcated or trifurcated entostyles depending on the wear stage. Among Southeast Asian large bovids, it differs from Bos javanicus (banteng) and Bos gaurus (gaur) in having a more developed postprotocristid on the p3 and p4, a metacentric chromosome-shaped molar in relation to the middle wear stage, a single large medial fossette on the upper molars, a flat lingual surface of the entostyle on the moderately to heavily worn molars. The M1 and M3 of Bos sauveli are almost more square and rectangular in outline, respectively, compared to those of other Bos species. Bos sauveli is usually smaller than Bos gaurus and Bubalus arnee (wild water buffalo), but is often comparable in size to Bos javanicus (Figs 26 and 27, and for the average of large bovid body mass, see Tab. 14).

According to the molecular phylogenetic analyses, the kouprey may have been domesticated in Cambodia ( Hassanin et al. 2006) and they are probably a feral animal derived from hybridization between Bos javanicus and Bos taurus indicus (zebu) ( Galbreath et al. 2006). However, the latter statement is not recently supported by the molecular sequences available for koupreys, bantengs, and zebus ( Hassanin and Ropiquet 2007). These authors indicated that the mitochondrial sequences of Cambodian bantengs are divergent from those of Javan bantengs, but similar to those of koupreys. They also proposed that the mitochondrial genome of koupreys seems to have been transferred by natural hybridization into the ancestor of Cambodian bantengs. The taxonomic status of koupreys is currently under discussion and additional molecular analyses on Southeast Asian bantengs need to be examined in the future. However, our taxonomic identification of Khok Sung bovids suggests an existence of the Pleistocene kouprey in Thailand because of its high similarities in dental features with the type specimen MNHN-ZMO-1940-51 and the specimen MNHN-ZMO-10801.