Molar crown inner structural organization in Javanese Homo erectus

Abstract

This contribution investigates the inner organizational pattern (tooth tissue proportions and enamel-dentine junction morphology) of seven Homo erectus permanent molar crowns from the late Lower-early Middle Pleistocene Kabuh Formation of the Sangiran Dome (Central Java, Indonesia). The previous study of their external characteristics confirmed the degree of time-related structural reduction occurred in Javanese H. erectus, and also revealed a combination of nonmetric features which are rare in the Lower and early Middle Pleistocene dental record, but more frequently found in recent humans. In accordance with their outer occlusal morphology, the specimens exhibit a set of derived internal features, such as thick to hyperthick enamel, an incomplete expression of the crest patterns at the enamel-dentine junction (EDJ) level, a sharp EDJ topography. As a whole, these features differ from those expressed in some penecontemporaneous specimens/samples representing African H. erectus/ergaster and H. heidelbergensis, as well as in Neanderthals, but occur in recent human populations. Further research in virtual dental paleoanthropology to be developed at macroregional scale would clarify the polarity and intensity of the intermittent exchanges between continental and insular Southeast Asia around the Lower to Middle Pleistocene boundary, as well as should shed light on the still poorly understood longitudinal evolutionary dynamics across continental Asia.

Late Pleistocene hominin teeth from Laoya Cave, southern China

“…Despite this difference, we should be cautious with interpreting it until more data is available. A M 3 from Hexian H. erectus (PA831) (unpublished data) and a M 3 from Java (NG0802.2) (see Figure 2 in Zanolli (2015)) are similar to that of recent H. sapiens in the distribution pattern of 3-D enamel thickness.…”

“…In addition, LYC1 does not have as many accessory ridges as in PA834-2. The NG92.3 and NG0802.2 of Java H. erectus display an EDJ surface as simple as that of LYC1 (Zanolli, 2015). However, the EDJ surface of the other M 3 (NG9107.2) is slightly more complicated due to the development of several accessory ridges (Zanolli, 2015).…”

Elucidating the evolution of hominid dentition in the age of phenomics, modularity, and quantitative genetics

“…As sample sizes increased so did our understanding of ranges of variation (e.g., Smith et al, 2012), but even today the misleading elegance of such dichotomous phenotypic simplicity continues to be employed (e.g. Horvath et al, 2014;Zanolli, 2014). …”

Enamel thickness and enamel growth in Oreopithecus: Combining microtomographic and histological evidence

“…i This study. and dentine horns enclosing a sub-concave occlusal basin commonly seen in fossil and extant hominoid molars, such as Ouranopithecus (Macchiarelli et al, 2009), Paranthropus and Australopithecus , Homo Skinner et al, 2008b;Zanolli, 2014;Zanolli and Mazurier, 2013), and in the living great apes (Skinner et al, 2008b(Skinner et al, , 2010. Assuming that Oreopithecus is closely related to the dryopithecines (Harrison and Rook, 1997;Moyà-Solà and Köhler, 1997), which almost invariably exhibit a low to only moderately elevated external crown topography (Alba et al, 2013;Begun, 2002), its tall occlusal reliefs could represent an autapomorphic feature developed under conditions of insular isolation.…”