The Sangiran Fossils: Assessing the Taxonomic Position Relative to other Asian Homo erectus Lineages

Ryan Harrod1*, Sharon Kuo2,3, Alexandra J. Zachwieja2, Johan Arif4, Gerad Smith1, Ted Parsons1, and Don Tyler5

Over the last decade there is a growing recognition that Homo species in Asia and Southeast Asia exhibit quantifiable morphological variation. We analyzed three-dimensional scans of undescribed craniodental material recovered from the Sangiran site on Java, Indonesia. The Sangiran hominin material included four mandibles either assigned to Meganthropus (Sangiran 6, Mandible D) or unattributed but considered robust (Sangiran 9, Sangiran 33). We compared the M1 and M2 crown dimensions of these remains to dental measurements of 756 other African, Asian, and European hominins from the Pleistocene and Holocene. M1 mesiodistal length separated the new Sangiran teeth from European Middle Pleistocene Homo (EMPH) (p < 0.001), Holocene humans (HH) (p < 0.001), Neaderthals (p = 0.005), and Upper Pleistocene Modern Humans (UPMH) (p < 0.001). M2 mesiodistal length for the new Sangiran material is significantly different from Asian Homo erectus, which includes the previously published Sangiran hominin material (p = 0.02), EMPH (p < 0.001), HH (p < 0.001), and UPMH (p < 0.001). M1 buccolingual length failed to differentiate the new Sangiran teeth from any of the other groups studied. M2 buccolingual length differentiated the new Sangiran material from EMPH (p < 0.001), HH (p = 0.002), and UPMH (p = 0.009). Our findings contribute to the growing evidence for hominin taxonomic diversity, and especially the island of Java by situating these partial craniodental scans within the broader taxonomic variation of Southeast Asian hominins in a global comparison.