The axis (C2) from El Sidrón and its implications for Neanderthal upper cervical spine form

Abstract

The atlas (C1) and axis (C2), the two first vertebrae of the spine, are key elements of the axial skeleton as they link the skull and the postcranium. As such, several works have focused on this region in earlier hominins (Gómez-Olivencia et al., 2007; Beaudet et al., 2020) and nonhuman Primates (Nalley and Grider-Potter, 2017). However, the study of the upper cervical spine of Neanderthals has been only included in more systematic works (Gómez-Olivencia et al., 2013; Haeusler et al., 2019), with the exception of the study of Palancar et al. (2020b). The latter presented the atlases from El Sidrón (Asturias, Spain) and compared them with other Neanderthals and modern humans, showing differences (see below) between them. The El Sidrón site (Asturias, Spain) has yielded more than 2300 Neanderthal fossils dated to approximately 49,000 years ago (Wood et al., 2013), making it the most complete Neanderthal assemblage known from the Iberian Peninsula (Fortea et al., 2003; Rosas et al., 2006, 2012). The axis from this Spanish site is the main subject of the present study.