Camelus thomasi Pomel, 1893

Martini, Pietro & Geraads, Denis, 2018, Camelus thomasi Pomel, 1893 from the Pleistocene type-locality Tighennif (Algeria). Comparisons with modern Camelus, Geodiversitas 40 (5), pp. 115-134 : 118

Camelus thomasi Pomel, 1893

Camelus thomasi Pomel, 1893: 14 .

Camelus thomasii – Pomel 1886: 504 (nomen nudum).

HOLOTYPE (by original designation). — Right maxilla with M1-M2 and part of the palatine bone, no. 7236001 in the Musée de Géologie, Algiers, Algeria ( Fig. 2E ); also Pomel (1893: pl. 3, figs 2-5; note that Pomel’s figures are inverted, and that the association of a M3 with this maxilla is tentative). From the late/terminal Early Pleistocene of Tighennif (formerly spelled “Tighenif”, also known as Ternifine or Palikao), near Mascara, Algeria.

REFERRED MATERIAL. — The whole collection of Camelus from Tighennif is referred to this species; the full list of specimens housed in MNHN and their measurements are given in the Table 1. In addition, we tentatively ascribe to the same species some specimens from the Middle Pleistocene of Oulad Hamida I quarry in Morocco, but they do not contribute to the definition of the species.

DIAGNOSIS. — A Camelus slightly larger than the modern species; pachyostosis weakly indicated in cranium (thick nasalia, thickening of the zygomatic arch posteriorly) and strongly so in the mandible; marked sexual dimorphism; V-shaped choanae; palatine foramina located anteriorly, at the level of P3 or P4; facial crest present; low placement of orbits; paroccipital process far from condyles; teeth small relatively to skull size; P1 located anteriorly, P3 with a complete lingual crescent; molars alveolarly broad with strong styles; mandible thick and low, especially anteriorly; coronoid process short, massive, slightly twisted and bent backwards; caudal mental foramen located anteriorly, or absent; p1 absent or located more anteriorly than in modern forms; p4 long, with a long metaconid; limb bones long; tibial tuberosity slender and very prominent; phalanges robust.

AGE OF THE SITE. — Historical data on the excavations and research at Tighennif can be found in Geraads (2016), who provided a faunal list, and concluded that the site is probably older than the Middle Pleistocene, as also assumed bySahnouni & van der Made (2009); it can tentatively be dated to c. 1 Ma. It is best known for its hominin remains ( Arambourg & Hoffstetter 1963), either referable to Homo rhodesiensis Woodward, 1921 (according to Hublin 2001) or closer to H. ergaster (Martinón-Torres et al. 2007) .

DESCRIPTION AND COMPARISONS WITH MODERN FORMS The best specimen is a relatively complete cranium, MNHN.F.TER1689 ( Fig. 1 ), first figured by Lhote (1987). Its description can be complemented with that of other cranial elements: the maxilla with imperfectly preserved teeth TER1816 ( Fig. 2A ), and the type-specimen MGA-7236001 (on the basis of photos kindly provided by Y. Chaïd-Saoudi, Fig. 2B ). Unfortunately,TER1689 is strongly dorso-ventrally crushed, so that the cranial surface consists of a mosaic of bone fragments among which sutures and details are hard to recognize. This crushing prevents reconstruction of the dorsal cranial profile and of the position of the front teeth relative to the occlusal plane of the cheek teeth. The basicranium is also poorly preserved and the right zygomatic arch is missing. In addition, the premaxillae are somewhat shifted posteriorly, and probably lack a few mm at their tips. By contrast, the moderately worn cheek-teeth are nicely preserved, but all teeth anterior to P3 are missing, except the left canine.

Overall size is close to the maximum seen in extant species (Appendices 1-3). The maximal length (measurement C1) of 575 mm exceeds that of all 31 measured C. dromedarius , and was surpassed (by less than 10 mm) in only two individuals out of 28 C. bactrianus ; given that this measurement is certainly underestimated because of the preservation of the premaxillae, it can reasonably be assumed that this skull was longer than that of all modern Camelus in our sample. Beside the larger size, the only proportions that differ significantly from those of the modern forms are the ones that indicate a shorter face and rostrum; considering the imperfect preservation of the premaxilla, these differences can probably be ignored. Dorsoventral crushing prevents fully reliable estimates of breadth at orbital and post-orbital levels, but on the whole there is no evidence that general cranial proportions differed much from modern forms.

Figures

FIG. 2. — Camelus thomasi Pomel, 1893, Tighennif (Algeria): A, maxilla MNHN.F.TER1816, occlusal view; B, maxilla with M1-M2 and tentatively associated M3, holotype no. 7236001; B1, right lateral view; B2, occlusal view; C, partial mandible 1900-27, dorsal view; D, partial mandible TER1688, dorsal view; E, partial mandible TER1686, dorsal view; F, mandible TER1683; F1, dorsal view; F2, lateral view; G, mandible TER1685; G1, dorsal view; G2, medial view. Holotype no. 7236001 (B) is housed in the Musée de Géologie (Algier); all others specimens are housed in the MNHN. Scale bar: F2, G2, 40 cm; 20 cm for all others.

FIG. 1. — Camelus thomasi Pomel,1893,Tighennif (Algeria), cranium, MNHN.F.TER1689: A, left lateral view; B, ventral view of the cranial basis (stereo); C, ventral view; D, dorsal view. Scale bar: 40 cm.