Étude taphonomique d’assemblages fauniques de sites à Homo erectus du dôme de Sangiran (Pléistocène moyen,Java central,Indonésie)

Since the sixties, the National Indonesian Center for Archaeological Research, in collaboration with the Gajah Mada University, organizes field excavations on open-air sites in the Sangiran dome, one of the most famous places of palaeoanthropological discoveries in Southeast Asia. That project led to the discovery of Homo erectus more or less fragmentary fossils, and to the collection of numerous mammal fossils in open-air localities such as Tanjung, Sendang Busik, Ngrejeng Plupuh, Grogol Plupuh and Bukuran. Most of the bone assemblages from these sites come from the volcanic-sedimentary Kabuh layers (Early Middle Pleistocene) deposited in a fluvial context. The herbivores dominate the assemblages. The best-represented species are large bovids like Bubalus palaeokerabau or Bibos palaesondaicus and smaller cervids like Axis lydekkeri. The carnivore are very rare, only a Pachycrocuta brevirostris in Bukuran. The taphonomical study of the collections, involving several common and also modern methods, is among the first carried out on Javanese sites. The high degree of fragmentation is attested by the dominance of splinters among the fossils. In most sites, teeth and member extremities (autopodial) prevail. Conservation and fragmentation of fossil bones is not the same at all sites. Water action, either chemical or mechanical, is predominant, regarding the origin and the modification of the assemblages. The climato-edaphic traces like oxides and concretions are well represented on the bone surface. Different methods were applied to study transportation and to document the sites contexts in the frame of the ancient riverine paleogeography. Carnivores are almost absent in the material and traces of their action are rare, only in Bukuran and Ngrejeng. The tools are rare, only a bola in Tanjung 82 and chalcedony flakes in Tanjung 63–64. Anthropic influence is only obvious at Ngebung 2, a site in the west part of the dome, supported by fossil observation and correlated to the occurrence of lithic artefacts. This site was excavated during the 1990’s by a French-Indonesian team and it is a site of comparison for our study. Several analytical methods could be applied for the first time on Pleistocene faunal assemblages from Java, for example, the study of the fragmentation, that of fissuration and the characterization of the fluviatile transport undergone by the fossils.     

Craniometric Variation within the Pleistocene of Java: The Ngawi 1 Cranium

The recently described cranium from Ngawi, East Java, is an important addition to the human fossil record. Several workers have placed Ngawi 1 into a grouping with the Ngandong and Sambungmacan specimens due to an overall metric and nonmetric similarity to those fossils. Multivariate comparisons of cranial shape have not been performed utilizing Ngawi, however, so it is unknown whether this specimen will fall within the current range of variation in those samples or if it will extend that range. Likewise, the inclusion of the Ngawi skull will allow a new test of the hypothesis that the African and Indonesian specimens currently allocated to Homo erectus exhibit a craniometric pattern that is significantly different from that seen in the Zhoukoudian crania. Mahalanobis distances will be used to examine the levels of variation present in a large sample representing the most complete African, Indonesian, and Chinese specimens of H. erectus. Statistical significance of the distances generated will be calculated using random expectation statistics. The results indicate that Ngawi shares strong shape similarities with the African and Indonesian specimens studied, and exhibits significant differences with the Zhoukoudian fossils. This supports earlier work by a number of scholars that found evidence of a unique craniometric pattern at that Chinese site. In addition, these tests indicate that cranial shape remained relatively invariant on Java for much of the Pleistocene. These findings, in conjunction with evidence for the appearance of unique nonmetric traits in the late-surviving Ngandong crania, suggest that the hominid populations of Java were relatively isolated for extended periods of time.     

Modern human origins in Australasia: Replacement or evolution?

The controversies surrounding the origins of modern humans have spawned two competing hypotheses, namely Replacement and Multiregional Evolution. The first suggests that modern Homo sapiens evolved first in Africa, as late as 140 ka, and subsequently inhabited the balance of the Old World. Conversely, the second hypothesis posits that modern humans evolved principally from local populations of archaic hominids indigenous to the major regions of the Old World. The hominid mandibular remains (ca. 1 Ma) from Sangiran, central Java, Indonesia, were studied in order to test these hypotheses. Non-metric comparisons were performed between these fossils and aboriginal H. sapiens from Africa and Australia. The Replacement model would be supported by a unique Afro-Australian grouping while Multiregional Evolution would be suggested by a Sangiran-Australasian group which would exclude the modern Africans. These data support the Multiregional Evolution hypothesis in that a plurality (eight) of the seventeen non-metric features link Sangiran to modern Australians, while only three exclusively group the humans from Africa and Australia. These results are suggestive of morphological continuity, which implies the presence of a genetic continuum in Australasia dating back at least one million years.     

A re-evaluation of the metric diversity within Homo erectus

Previous work by several researchers has suggested that the cranial sample from Zhoukoudian possesses a unique metric pattern relative to the African and Asian specimens assigned to Homo erectus. The current study readdresses this issue with an expanded fossil sample and a larger and more comprehensive set of cranial measurements. To test the patterns present in the assemblage, canonical variates analysis was performed using a covariance matrix generated from the Howells data set. From this, interindividual Mahalanobis distances were computed for the fossils. Random expectation statistics were then used to measure statistical significance of the Mahalanobis distances. The results show that the Zhoukoudian hominids exhibit a unique metric pattern not shared by the African and Indonesian crania sampled. In these tests the Hexian calvaria resembled the African and Indonesian specimens and differed significantly from the craniometric pattern seen in the Zhoukoudian fossils. The Zhoukoudian specimens are characterized by a wide midvault and relatively narrow occipital and frontal bones, while the African and Indonesian crania (including Hexian) have relatively broad frontal and occipital dimensions compared to their midvaults. These results do not suggest that a multiple-species scenario is necessary to encompass the variation present in the sample. Based on the current evidence it is more probable that this variation reflects polytypism influenced by environmental adaptation and/or genetic drift.     

Trachypithecus auratus sangiranensis,A New Fossil Monkey from Sangiran,Central Java,Indonesia

We describe a new extinct subspecies of the Javan lutung—Trachypithecus auratus sangiranensis—based on an isolated, tooth-bearing upper jaw. The specimen was in volcanic breccia situated between the Lower Pucangan and the Upper Kalibeng Formations 500 m south of the village of Sangiran, near Surakarta, central Java, Indonesia. The new fossil monkey bears morphological similarities to the two living species of leaf monkey from Java, Presbytis comata comata and Trachypithecus auratus auratus, and to the Middle Pleistocene form, Trachypithecus cristatus [=auratus] robustus, from Tegoean, central Java. It is significantly larger than any of these forms, and differs from them in details of dental anatomy. Because the greatest number of similarities are between the new fossil and Trachypithecus auratus subspecies, we designated the specimen as T. a. sangiranensis. The geochronological age of the breccia from which the fossil came, is 1.9± 0.05 Ma (million years), making T. a. sangiranensis one of the oldest fossil monkeys from eastern Asia.     

Brief communication: two human fossil deciduous molars from the Sangiran dome (Java, Indonesia): outer and inner morphology

Currently, the human deciduous dental record from the Pleistocene deposits of the Sangiran Dome, Java, consists of only eight specimens. Here we report two deciduous crowns collected near the village of Pucung. While their precise geo-chronological context remains unknown, a provenance from the Early-Middle Pleistocene Kabuh Formation, or from the Early Pleistocene "Grenzbank Zone," is very likely. These isolated specimens consist of an upper first molar (PCG.1) and a lower second molar (PCG.2). Taxonomic discrimination of the Indonesian tooth record is difficult because of the convergence in crown size and appearance between Pongo and Homo. Accordingly, as PCG.2 still bears a concretion masking most of its features, we coupled the outer analysis of the two specimens with an investigation of their inner morphology. In addition to external characteristics, virtual imaging and quantitative assessment of inner morphology and tissue proportions support an attribution to the taxon Homo, and we preliminary allocate both specimens toH. erectus.     

Molar crown inner structural organization in Javanese Homo erectus

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. Am J Phys Anthropol 156:148–157, 2015 © 2014 Wiley Periodicals, Inc.     

南京直立人与印尼、周口店直立人的面颅形态比较

本文对南京直立人1号头骨与印尼Sangiran17头骨和周口店11号头骨作面颅形态上的比较。结果表明,南京1号头骨的面颅与周口店11号头骨的有许多共同的形态:较小的面颅尺寸、眶下区呈扁平状、较扁平的上部颜面、眶上圆枕较纤细、中眶型的眼眶、发育有颧切迹、上颌骨颧突基部位置较高等。南京1号头骨的面颅在另外一些方面显示出与Sangiran17头骨的形态上相近:阔上面型的面型、眶上圆枕内侧部比外侧部稍靠前、眶上圆枕下缘略呈平直状、鼻梁发育有中矢锐嵴、鼻梁横向呈峰状拱起、颧骨下缘外展、颧结节相对位置稍偏外侧、颧骨较高等。南京直立人面颅兼具周口店直立人11号头骨的和印尼直立人Sangiran17头骨的形态。从南京直立人的面颅形态可以推测我国南方的与北方的直立人群之间在体质形态上已经出现一定程度的地理变异。南京1号头骨面颅上的某些形态特征,如颧骨下缘外展等,可能反映了特征的梯度变异现象。这些特征的梯度变异的成因目前还很难确定。     

When did Cuon reach Java? – Reinvestigation of canid fossils from Homo erectus faunas

The presence of the genus Cuon during the Pleistocene of Java is attested by the endemic species C. sangiranensis and C. crassidens, sometimes classified as C. alpinus, a species that is also part of the Holocene fauna and has persisted until today. The current study revises the fossil canid material from the Sangiran Dome, previously assigned variously to C. sangiranensis, C. crassidens, C. alpinus, C. javanicus, and C. trinilensis. It aims to reinvestigate the arrival of Cuon in Java, in particular in relation to the late early Pleistocene endemic canid of Java: the Cuon-sized Xenocyon trinilensis, which had evolved in situ on Java from the large X. merriami, and which could be a potential competitor to early Cuon in case of contemporaneity. We found that a mandible fragment from Pandejan (holotype of C. crassidens) shows a morphology typical for C. alpinus. However, a maxilla and a mandible from the Bapang Formation at Sangiran, including the holotype of C. sangiranensis, is here assigned to the early dhole species C. priscus. Our results indicate that Cuon was already present in Java during the early middle Pleistocene and probably arrived as part of the immigration events during the Kedung Brubus faunal stage. Since X. trinilensis and Cuon are both hypercarnivorous medium-sized dogs, similar ecological niches are expected for both species. Thus, X. trinilensis probably was outcompeted and replaced by C. priscus. In turn, the latter species was replaced by the extant species, C. alpinus, during the Nangdong faunal stage, likely as part of the next immigration phase, which then disappeared during the tropical rainforest fauna of the Punung faunal stage and re-entered at the onset of the Holocene.