Early Modern Human from Tianyuan Cave, China

Chapter 8 The Tianyuan 1 Axial Remains

88 C h a p t e r 8 The Tianyuan 1 Axial Remains DESPITE THE relative completeness of the Tianyuan 1 limbs, the axial skeleton is poorly represented. It consists of an essentially complete second cervical vertebra (C2, or axis), a partial manubrium, and two elements of the mesosternum . In addition to minor degenerative osteoarthritis on the axis (Chapter 12), the axis is of note primarily for its asymmetry. The sternal pieces provide some indication of their size. Second CervicalVertebra The C2, or axis, of Tianyuan 1 presents few details of note for a human second cervical vertebra (Figure 8-1). The caudal body has a fully attached annular ring, which remains prominent dorsally and ventrally. The cranial facets are largely flat laterally, and then dorsoventrally convex closer to the dens. The caudal facets are essentially flat. The dorsal tip of the spinous process is bifurcated caudally, but it is single cranially with a prominent midline crest running along the cranial side of the process. The overall height of the Tianyuan 1 axis (maximum, or ventral height) of 36.7 mm (Table 8-1) is unexceptional for a Late Pleistocene human second cervical vertebra (Table 8-2), or for a recent human one (Hasebe, 1912; Lanier, 1939; Stewart , 1962a). There is considerable variation in C2 heights; curiously two of the tallest individuals in the comparative sample [Qafzeh 3 and Skhul 5 (McCown and Keith, 1939; Vandermeersch, 1981)] have rather short axes (Table 8-2). The Dens The dens appears slightly waisted adjacent to the cranial intervertebral facets , but the “waisting” is produced by the lateral expansion of the facet for the an- THE TIANYUAN 1 AXIAL REMAINS 89 terior arch of the atlas. The dorsal side of the dens shows little lateral expansion. The groove for the transverse ligament of the atlas on the dorsal dens is weakly expressed. The main aspect of note is the dens’s relatively small height, or craniocaudal distance from the medial ends of the cranial facets to the dens tip (not including the osteophyte on the dens tip). Its height of 13.2 mm (Table 8-1) is among the smaller of the few sufficiently complete Late Pleistocene axes for whom data are available. It is matched by a third of the other Late Pleistocene axes providing data, including those from the small Minatogawa 1 and 2 skeletons, the small Dolní Vĕstonice 3, the (possibly pathological) Dolní Vĕstonice 15 C2, the otherwise small Qafzeh 3 and Skhul 5 axes, and the early Neandertal Krapina 103 axis (Table 8-2). But if its dens height is compared to its total ventral height, or maximum height (Figure 8-2), the proportions for Tianyuan 1 place it below all of the other Late Pleistocene specimens and a recent human eastern Asian sample (Hasebe, 1912). There is little overall difference across the comparative samples, either Late Pleistocene or recent. It is unclear what the significance of this relatively, but not absolutely, small dens height might be. Figure 8-1. Tianyuan 1 2nd cervical vertebra (C2: axis). Upper left: cranial view; upper right: caudal view; bottom: dorsal view. The vertebra is oriented with respect to the cranial articular facets. Scale in centimeters. CHAPTER 8 90 The Spinous Process The spinous process presents a prominent crest cranially, which rises above the cranial margins of the laminae and reaches the level of the medial margins of the cranial facets, or the level of the base of the dens. Caudally the process is distinctly bifid, with completely separated right and left caudal margins and dorsocaudal tubercles . In cranial view, the spinous process does not appear to be bifid, since it Table 8-1. Osteometric dimensions of theTianyuan 1 second cervical vertebra (axis), in millimeters except for the foraminal areas. Right Left Dorsoventral diameter 52.3 Cranial external articular diameter 48.2 Cranial internal articular diameter 14.7 Caudal external articular diameter 47.81 Caudal internal articular diameter 22.2 Canal dorsoventral diameter (M-10) 16.3 Canal transverse diameter (M-11) 22.7 Lamina height2 11.4 13.7 Spinous process length—maximum 20.2 Spinous process length—midline3 19.7 Spinous process tip height4 13.9 11.7 Total height to dens tip—dorsal5 32.0 Total height to dens tip—ventral5 36.7 Body ventral height (M-1)6 23.5 Body dorsal height (M-2)6 18.8 Dens height (M-1a)5 13...